Well, I´m a chemical engineer, and basically, you just broke down the essentials of the different processes: Mixing the chemicals according to the recipe, add catalyst as required (e.g. if an iron oxide catalyst in required, a rusty piece of junk from an old car will do the job, yet it will not be as effective as smaller particles with a good dispersion in the reactor, in other words: the reaction will take longer), set pressures and temperatures, give it some time for the chemistry to happen and proceed to downstream processing (rectification...). On the process of steam reforming for hydrogen production: yes, it does release CO2, but burning fossile fuels to make electricity and use the electric energy to do water electrolysis would be less efficient, releasing even more CO2 than steam reforming itself. The details of processing can be summarized as following: - handling toxic chemicals (hydrazine) requires a vast amount of savety equipment: overengineered vessels and pipes, sensors to monitor unwanted releases, protective gear for the workers - handling corrosive substances does require expensive materials that are able to withstand the corrosive stuff and savety equipment for the workers of course - handling cryogenic substances requires loads of insulating materials, special lubricants, pumps and valves with extremely tight tolerances and protective gear, hydrogen production and storage in particular requires loads of sensors to detect hydrogen and special precautions to prevent the formation of an explosive mixture with oxidizers including plain air - handling pressurized substances requires the vessels and pipes to be strong enough, which usually means beefy wall thickness of the vessels, piping and instrumentation. The tricky part is to develop sensors for the different chemicals, that are sensitive enough to detect contaminations at a rather low level, but are insensitive for other stuff. The rest (designing a plant that is save, from fire extinquishers to the girth of electrical wiring, from escape routes to ease of maintainance) is a matter of experience that has been accumalated over the last century and is appied on any chemical plant to a certain extend, as required by local laws and regulations. So yes, when you look into the details, it gets complicated very soon, but that is exactly why there are experts like engineers after all: Anyone can build a hut from branches that were cut from trees, but it requires lots of knowledge to build a skyscraper people enjoy living in. Last but not least: Yet another great video for those that are interested in rocket science. Two thumbs up, Scott!
1000% There is so much engineering that goes into our life that 99% of people dismiss. And this is just the rocket science... (and just the propellent side)- which there are people posting, from their smart phones, that "spaceflight is a waste of money". Yes, you can post the "waste of money" from your phone... only **because of spaceflight**! Thank you for posting the conundrum of processes that happen in this industry!
"On the process of steam reforming for hydrogen production: yes, it does release CO2, but burning fossile fuels to make electricity and use the electric energy to do water electrolysis would be less efficient, releasing even more CO2 than steam reforming itself. " On the other hand, using other means to produce electricity, such as solar or nuclear, would make hydrogen production much cleaner.
I'm a chemist and if I can make two grams with 30% yield, over three days from reagent grade starting materials without poisoning myself I'm happy. Very much harder to run an industrial process and I am very impressed by chemical engineers' ability to make useable quantities in reasonable times with sustainable economics and enough safety for workers to stay safe.
does kind of make it easy to understand why RP-1 is so popular for rocketry on a budget though, From the ground side of handling it there is no exotic requirements. the main thing I know about chemical reactions at the industrial scale is temperature control is a huge thing, As from watching videos on the USCSB channel. Some reactions get very perky if they have an excursion from their intended temperature range.
@@kangirigungi You´re absolutely right, electrolysis can easily done from electric energy from renewable or nuclear scources. But on a global scale, nuclear and renewable energy is less than 20 % of the energy mix and electrolysis is more expensive than steam reforming. Additionally, the vast majority of the hydrogen produced globally is used in refineries anyway, so the rescources for steam reforming are already on site.
Scott, I as a PhD chemist, am impressed how layman-y you managed to make all the process sound. If I had to explain all to a layperson I could NOT be able to simplify all so much, yet I think you managed to keep pretty much all chemically accurate yet clear to a non-expert. You even got the parahydrogen thingy accurate. Bravo, from someone with a PhD from a top-A-tier university in the US. You are a great science communicator one minute point I would have made at the end is that all these chemical steps pile up such that at the end you pretty much compress as much chemical energy you can in a certain mass/volume so it can become rocket-relevant. all those steps are like walking up a stairway, and after you do it enough, you reach the top of the Empire State Building, ready to release the potential energy you stockpiled. you kinda need the chemical equivalent of that for rocket fuels.
I am a chemist, retired now, and you did an excellent job of summarizing for the non-chemists how these rocket fules are made. The chemistry is well known and the really hard part of making rocket fuels is not the chemistry, it is the chemical engineering, the mechanics if you will, for . Your diagrams and explinations did a great job of explaining what the fuels are and how the mechanicl processes work.
@@kindlinProbably more about the efficient mass production, piping (pressures/wall thickness), thermal insulation, tolerances, (with hydrogen especially) sealing, etc. You want to use corrosive agents? That requires other materials to make it work than for example dealing with hydrogen - an atom so small it doesn't want to stay contained. All the safety regulations and equipment are disregarded for the sake of keeping the text wall a bit shorter.
4:40 The hydrotreating happens AFTER fractionation. Then, you fractionate a second time to eliminate the light ends which are typically produced from hydrogenating molecules like sulfides (R-S-R' + 2.H2 -> H2S + R-H + R'-H) or thiols (R-SH + H2 -> R-H + H2S) and from the inevitable cracking of a part of the feedstock (few % typ.). If you want a precise cut, you may also want to cut the bottom at high reflux, to eliminate heavy ends that were either created by the odd polymerization (very small fraction
I think you meant ped^H^H^H^H chemistry. After all, consider your audience. And if anyone says "OK boomer" to you for using "^H^H^H^H" to mean 4*backspace, hit them with your cane! disclaimer: This message written on a VT100.
@@Anvilshock Because I was too lazy to type them and just cut and pasted from the OP. Isn't that how most egregious errors are introduced into text documents?
@@dziban303 didnt even mention valence, and now a bunch of people think they understand something they have no clue of XD. Even saw one idiot questioning if college was a good idea if it could be explained in 5 minutes lmao
Small correction: it is the nuclear (proton) spins that distinguish the para and ortho forms of H2, not the atomic spins which usually refers to the electron spin. In the H2 molecule the electron spins are in a spin singlet, it is the total spin of the two protons that distinguishes the two spin isomers.
Great reference to John D.Clark's Ignition! It is an absolutely fascinating read (though a bit technical at times for non-chemists, I presume). The gist of it is that it's not really difficult to synthesize some of these things, but handling is an entirely other matter
Right! Clark could have named his humorous "informal history" BOOM! (which is not what you want in a propellent). I agree with your assessment of his book. He keeps the chemistry concise. Those of us with any interest in reading his book usually have the know-how. John Clark is an important figure who's personal stories are historically important.
What is really impressive about Dr. Clark is that, in all his years working with substances that were (to paraphrase the introduction) explosive, corrosive, or mind-blowingly toxic, and often all three at once, his working group did not suffer a single time-lost incident. He must have been, for all his wit and humor, an absolute tyrant about proper safety procedures.
wish I had two semesters of college organic chemistry under my belt! If this was more educational than your classroom time, I’m wondering whether free taxpayer funded college is a good idea 🫢
@@kamakaziozzie3038 lol, your dunning kruger is showing. Organic Chem is one of the broadest and most important subjects, it describes virtually all the processes of life and most of the processes of industry. This is so grossly over-simplified he never even mentions valence or electron shells or bond energies or angles, all the things you use to figure out how to make a reaction happen (and what you made). Also - what kind of idiot doesnt see the value in a more productive and capable workforce, if not the societal value of a world that isnt full of morons?
Thank you for explaining all this Scott! At our integrated Steel Factory we have several Linde Gas Air separation plants, supplying us with mainly Oxygen for several production processes. Big tanks of LOX, LN2 and Argon, also transported off site to other Linde Gas customers in the food industry. We also have big pressure tanks for fire suppression in certain areas, filled with either Argon or the latest Argonite A2N2 mixture. Smarter everyday! 😉
Ph.D. chemist here. Pretty good explanation! The hard parts of these processes are the exact pressure, temperatures, catalysts, and equipment used to run them. Almost all of which are industrial secrets, patented, or a mix. So if you somehow had more details to share, you’d probably get some strongly-worded letters from attorneys. Best to let them keep their secrets.
No, that mindset also holds back advancement which can't be made in that type of atmosphere. all we need is retired people to share data which they always do also isn't there a version of this that you learn by just knowing chemistry basically.
@@johnk7302 Doing things on a small scale has some significant differences to large scale, there are unique challanges imposed with mixing and temperature control and every company has it's own methods of dealing with the issues.
Patented details cannot be kept secret, that's the point of the patent process: A time limited monopoly in exchange for revealing your industrial secret for the competitors to duplicate the moment the time is up.
The hydrazine synthesis sends chills down my spine. NaOCl and ammonia easily gives you NCl3, an absolutely terrifying explosive. I don't want to know how many injuries were incured to dial in the process parameters to make it work.
@@danielkorladis7869 Chlorine gas is relatively easily handled and detected and has a characteristic smell, therefore not the worst occupational hazard. An extremely shock and light sensitive explosive that may pool somewhere on the other hand...
@@danielkorladis7869 This is a common misunderstanding: The reason you don't mix ammonia (NH3) and bleach (NaOCl) is because it forms chloramines, which tend to be strong irritants, particularly NCl3. And no, this is not the same as mustard gas, as some like to claim. For chlorine gas to form, the bleach would have to react with acid. But yeah, NCl3 is plenty nasty on its own. In the early 20th century, it was used as a flour bleaching agent, and there is a hypothesis that overuse of NCl3 caused a mass psychosis incident in the French Village of Point-Saint-Esprit (this is a fascinating rabbit hole to go down, btw) by oxidizing the proteins in their flour into neurotoxins.
I worked in a cryogenic production plant in the US Air Force many years ago. We produced liquid oxygen and liquid nitrogen. The two are separated through distillation. It's basically the compression of air then the expansion, either through an expansion valve (high pressure plant) or through a turbo expander (low pressure plant). The now liquid air was directed to a distillation tower where the heavier oxygen settled in the bottom and the nitrogen on top.
@@BacklTrack As a neuroscientist (retired), I'm also in awe of engineers, especially chemical (and electrical). I couldn't handle the math, let alone the theory, let alone the creativity required to employ the vast body of human knowledge in novel ways. Scientists generate knowledge. Engineers figure out what to do with that knowledge, which I think is far more challenging. I think the easier part of their job is telling the scientists what we got wrong.
It was observed in 1910s and proposed different molecular types/states for H. Later, in 1920s they were first produced separately. Quantum mechanics formed in late 1920s, Heisenberg got his Nobel for it in 1932 And this theory momentarily explained, what was happening with molecular hydrogen
Chemistry student here: It is relatively easy to synthesise things like Hydrazine on a large scale. The hard part was getting there, and optimising the process. And the challenge of keeping the production affordable in the face of economic factors.
You explained the chemistry really well. There are a lot of little things to do and get right for every different type of chemical reaction. For this type of video and audience it would be way too much to get into that level of detail.
Can you point to someone that can get more into the details? I’m genuinely interested in chemistry and videos help a lot. Not the last few, as I know their decomposition compounds and enjoy living, but distilling hydrocarbons sounds like a cool process, as well as chilling air to the tens of kelvin instead of hundreds.
@@theinsane4469Here's a handful of youtubers that cover chemistry Some more than others. youtube.com/@NileRed youtube.com/@NileBlue youtube.com/@NurdRage youtube.com/@DougsLab youtube.com/@Chemiolis youtube.com/@ExtractionsAndIre youtube.com/@ExplosionsAndFire youtube.com/@theCodyReeder youtube.com/@codysblab4771
I'm so glad I found your channel. Your delivery is amazing, its light and breezy not preachy and boring. You take complicated topics and brake them down into easily digested chunks. I wish you all the best with the channel.
Hi Scott, chemist here. You have explained it rather nicely without going into specific details. I am glad that chemical industry gets its fair share of appreciation because we tend to get only more than fair share of cancer.
Heyy! I made some Hydrazine and NTO for my High School Chemistry project a few months back! Primarily used Raschig process for the hydrazine and fuming Nitric acid for the NTO. It was super fun to see the reaction!!! The hard part was preparing the NaOCl, because the ones we use in pools are calcium. Had to work literally on Ice with an ice bath all the way, but it was definitely worth it to see the flames!
One of my most loved books is a copy of “Rocket Power And Space Flight” by G. Harry Stine from 1957. He was one of the researchers at White Sands doing some of the early research with the Aerobee and Nike rockets. It has incredibly interesting breakdowns of what they were doing with fuels and cycles at that time and it’s interesting how little the fundamentals have changed.
I work with the cryogenic stuff daily. Though cooling the liquid oxygen might increase its density a bit, I would think its main advantage would be that they have a better margin from the oxygen temperature in the tank to its boiling point. Together with a further pressurization of the tank this is supposed to prevent cavitation of the oxygen liquid in the turbopumps during flight, which is really bad. So the cooling serves as a security measure as well and gets them more time of usable oxygen.
I believe the advantage of using sub-cooled oxygen is principally due to its higher density. Temperature margin might be a factor as well but whenever I've read about the use or planned use of sub-cooled or slush cryogenic propellants, the focus is always on their higher densities and what effect it has on rocket performance.
Hydrazine can be used as a monopropellant - expose it to a catalyst and it will spontaneously and energetically decompose. There are some emergency systems that depend on this arrangement in case of power loss for a critical application where the hydrazine is released across a catalyst and the decomposition products are fed into a turbine tied to an electric generator. Doesn't last very long -- for those critical applications - deemed long enough.
All those reactions use cheap catalysts, like pure iron, or iron oxide. However they also need those catalysts to be ultra pure, so the iron used to make them has to be specially refined, to remove all of the other metal contaminants that normally are added to improve strength and ductility, as they can also act as catalysts and make unwanted side reactions.
Excellent stuff. As to complications, there's always a lot hidden behind the simple statements of "at pressure" and "at temperature". Just ask those Fusion physicists.
This is the kind of think I'd love to see a wiki for; the nitty-gritty of how these really work with enough details that someone with access to the right catalogs and enough money could set up production. (And where someone who reads the warnings section can run it without losing any fingers, friends or family.) What would be totally cool would be to try to expand that all the way to a "tech tree for the real world: everything you need to know to build Starship starting from picking up stuff off the ground and identifying it".
As a chemist, this is a useful summary, especially since most of us who don't work in these kinds of bulk chemical industries don't necessarily know much about routes to basic chemicals like hydrazine! I've used hydrazine hydrate a few times (a lot less scary than the anhydrous stuff) but never really thought about how it is made!
Chemistry seems to alway go over my head, but this simplified things a bit for me. Amazing how some of these processes create interesting byproducts, like salt and water!
Ready Salted Hydrazine! An exciting new flavor, not suitable for human consumption. Not something I'd ever want to work with though, as quite a few early rocket fuel pioneers discovered.
@@brolohalflemming7042 just watching, I got chills… I’m certainly no chemist, but I understand the basics. I know what most of those fuels break down into and I definitely wouldn’t want to experience that experiment… Being more of a history nerd myself, I have read quite a few account of labs exploding purely because of the reactants and decomposition compounds. Exciting stuff, but only to read about…
I'm no chemist, but I play one at home. Stable compounds like salt and water are often used to crowbar more unstable compounds into existence. When you mix some molecules whose constituents like to form salt and/or water, but there are some atoms left over after, those have no choice but to form a compound themselves. The calcium carbide to acetylene reaction is a good example, though somewhat reversed. Calcium carbide really really wants to form calcium hydroxide, so it'll tear apart water molecules to get to the OH. The remaining hydrogen and carbon forms energetic C2H2. Sulfuric acid catalyzes many reactions that form water, by grabbing onto the formed water so it can't dilute or balance out the reaction. Sulfuric acid is famously grabby towards water - maybe you've seen the demonstration of if tearing water out of sugar, leaving a carbon foam.
@@galfisk Yep. When I was at school, I condsidered ia careeer in chemistry, but switched to engineering instead. And learned a healthy respect for MSDS and safety lables. The Internet has been great for reinforcing that message. I think military and rocketry chemistry is one of those delicate tightropes to walk. You want to create an energetic compound, but you also really want it to be stable enough to store, handle, force through turbopumps etc. Or simple hypergolic fuels that'll happily rapidly oxidise anything organic, including pilots and fuel handlers. Or the great 'Things I'll never work with' blog. We're carbon-based life forms, but can be un-lifed by a few C-N molecules. Or faster if you force a dozen C-N bonds into a molecule and look at it funny. It's one of those subjects I'm content to learn about from a very safe distance!
A couple years ago I picked up a copy of Ignition! by John D Clark. The shit these guys were getting up to in the 40's and through the Cold War was just nuts.
Another fantastic video. Perfect! I have yet to see such a succinct and non-patronising science video maker/educator. I read Ignition on your recommendation. If you'd mentioned the power of the nitrogen bond it'd be legendary.
@@General12th No, he just mentioned how it's simpler than a lot of chemistry classes. Scott's video still explains the concept nicely and simply considering the topic, but chemistry classes often have to get into the far more nitty-gritty details so you can recreate it in the lab yourself.
I mean sure, it isn't as easy as you described it. But everything is correct, and it's super understandable! Props for breaking down a difficult topic like this so successfully!
This video adds a great perspective that we often miss, just as how we often look at the design of a rocket as the challenging part where, in reality the manufacturing is the greatest work. Same with the Fuel apparently.
When I heard bleach + amonia I thought "are you crazy? That's incredible dangerous "(you can actually die because of that if you mishandle cleaning products). Then I remember you were talking about hydrazine. I know people use special suits to even come close to a hydrazine source.
@@danielkorladis7869 dimethyl Mercury is worse. A few drops even with a latex glove and you die months later. And it was thought as rocket fuel although never actually tested.
Very cool Scott. I work in a chemical plant that produces Ethen (Ethylene), which we use to produce polyethylene. You did a great job explaining this subject and how the same processes are used to produce rocket Fuel.
Make it sound easy? By the time you got to the beginning of hydrazine my head was already spinning, need rewatch few times to grasp. Thanks for tasty knowledge Scott!
I love "Ignition" by John D. Clark beause of the cool stories behind developing the extreme chemicals in the early days of extreme rockets. Not an easy read though...
I've not been a chemist for a few years now but that was an excellent explanation. Most of the reactions here are not what your average everyday lab chemist would do. They either produce things that you'd just buy or things that are too dangerous for day to day work, looking at you hydrazine. Saying that though all the reactions are well understood, the real difficulty is in the engineering and producing them safely at scale.
Chemist here. It's not quite as easy as you said! :P But, joking aside, the video is great. Of course you couldn't get into the details of chemical processes, but you gave an excellent high level overview. Thank you!
@@QuantumDoze They're easy to find. The problem is more that they're hard to find in reasonably small quantities. If you call Linde or AIr Liquide and order a tank truck of LN2 they'll be over at your place tomorow morning and will probably throw in a complementary dewar. But if you try and order just one or two dewars they'll likely laugh and hang up on you.
I am engineer for NASA and SpaceX and Blue Origin I am also a chemical doctor and nobel prize winner and fellow at MIT. This is the greatest explaination of rocket fuels available in the history of mankind!
There is a quite funny book on the history of rocket fuels “ ignition” by John d Clarke, it doesn’t go so much into chemistry but the race about who was going to mix this with that and not blow themselves up is quite humorous.
Hi Scott…. There’s a book, “Ignition!: An Informal History of Liquid Rocket Propellants” by John Clark. A first person narrative on the development and often dangerous experimentation of all manner of liquid rocket fuels. Very entertaining, extremely informative, and rather humorous. Highly recommended…
Check out Scott's video "The most dangerous rocket fuels ever tested." Scott has a copy of the book, and he references some of the humorous sections in the video.
@@matd675 yeah, I was going to say that I first heard about that book from this channel, but perhaps it was xkcd. There are a few incorrect diagrams in the new reprint, but it's an enjoyable read.
I'm a chemist by education, if not by trade, so I can't speak to the engineering challenges, but I thought you did a great job with an overview of the chemistry.
Regarding the Linde process: Nowadays you use turbines for the decompression step to get rid of the energy in the gas, not a throttle valve and you also use a similar fraction column as an oil refinery.
The distinction between the Claude process and the Lindie process is an important one. Cooling with throttling expansion is very inefficient because all of the energy stored in the compressed gas shows up as friction heating of the throttle valve. When you make that gas do external work as it expands it ends up far colder for a given pressure difference. Jon
This is a great video! Though, it does seem like a prime candidate for splitting into chapters by using some timecodes in the description. I think these are right: 00:00 Introduction 01:27 Ethanol 02:42 RP-1 05:05 Methane 05:59 Liquid Oxygen 08:44 Liquid Hydrogen 12:04 Chemical plant introduction 12:45 Hydrogen peroxide 13:34 Ammonia 14:25 Nitrogen tetroxide 15:13 Hydrazine 16:53 Wrapping up, fly safe
I'm one of those Chemists out there. You did a pretty good job. Yes it's always more complicated, but you made no glaring mistakes that I would criticise.
2 months ago Man even your way in explaining chemistry is so clear, we can't thank you enough RageDavis 2 months ago (edited) Well, I´m a chemical engineer, and basically, you just broke down the essentials of the different processes: Mixing the chemicals according to the recipe, add catalyst as required (e.g. if an iron oxide catalyst in required, a rusty piece of junk from an old car will do the job, yet it will not be as effective as smaller particels with a good dispersion in the reactor, in other words: the reaction will take longer), set pressures and temperatures, give it some time for the chemistry to happen and proceed to downstream processing (rectification...). On the process of steam reforming for hydrogen production: yes, it does release CO2, but burning fossile fuels to make electricity and use the electric energy to do water electrolysis would be less efficient, releasing even more CO2 than steam reforming itself. The details of processing can be summarized as following: - handling toxic chemicals (hydrazine) requires a vast amount of savety equipment: overengineered vessels and pipes, sensors to monitor unwanted releases, protective gear for the workers - handling corrosive substances does require expensive materials that are able to withstand the corrosive stuff and savety equipment for the workers of course - handling cryogenic substances requires loads of insulating materials, special lubricants, pumps and valves with extremely tight tolerances and protective gear, hydrogen production and storage in particular requires loads of sensors to detect hydrogen and special precautions to prevent the formation of an explosive mixture with oxidizers including plain air - handling pressurized substances requires the vessels and pipes to be strong enough, which usually means beefy wall thickness of the vessels, piping and instrumentation. The tricky part is to develop sensors for the different chemicals, that are sensitive enough to detect contaminations at a rather low level, but are insensitive for other stuff. The rest (designing a plant that is save, from fire extinquishers to the girth of electrical wiring, from escape routes to ease of maintainance) is a matter of experience that has been accumalated over the last century and is appied on any chemical plant to a certain extend, as required by local laws and regulations. So yes, when you look into the details, it gets complicated very soon, but that is exactly why there are experts like engineers after all: Anyone can build a hut from branches that were cut from trees, but it requires lots of knowledge to build a skyscraper people enjoy living in. Last but not least: Yet another great video for those that are interested in rocket science. Two thumbs up, Scott!
Reminds me of when I read "Ignition" by John Clark. To paraphrase: "It was a good day when we didn't blow up the lab. It was a better day when we DID blow up the lab." (for science)
I made a number of rocket fuels as a teenager back when you could ask your local pharmacist for the ingredients and nobody batted an eyelid. However, I couldn't find any recipes, so working on the idea that the difference between an explosive compound and solid rocket fuel was the rate of oxidation, I went to the local University library, found a book on explosives, copied down the formulae (I didn't know what the formulae meant so I treated them as proportions) and went home. Some burned, some didn't, but the only one that burned furiously enough to power a rocket but not explode was wasted and I never got the chance to make the rocket with it. Here's why: Rather than paying attention to my chemistry classes, I used the school's glassware to mix my fuels. I had just finished one with, I think from bad memory, potassium permanganate and carbon black? I left it in a petrie dish on the bench. There is always one idiot classmate, isn't there? He went up to it with a box of matches and voila! the chem lab lacked curtains, and I was asked not to do any more chemistry. And what was worse, I hadn't written down the manufacturing process. Of course it was the 70s, so I didn't get a visit from any spy agencies...
Granted it may not be as relevant to rocketry as it is to sustainable (bio-) fuel, but Dimethyl Ether is neat! Covering that and maybe nitric acids would be cool (at least in my biased opinion) Also i don’t know the theoretical ISP (it may be quite poor) but given the simplicity of Pressure Fed Designs, a DME-Nitrous Oxide Rocket would be a neat storable pressure fed rocket! Kind of similar to that Propane rocket design you mentioned some company was working on (although bio/syn *proper* propane is far mor difficult to make than similarly stored DME)
@@hicknopunk Ah, devil Ether... it makes you behave like the village drunk in some early Irish novel. I knew we'd be into that rotten stuff soon enough.
Nitric acid is basically nitrogen dioxide mixed with water and ether takes ethanol as a basis and doing an acid catalyzed displacement. I have the impression that those fules are not as prevalent anymore, probably why the ave been left out.
@@cahdoge You are thinking of Ethyl Ether probably, not Dimethyl Ether ;) But yeah I’ve read up a bit on Nitric Acid too, although I think it being covered in a part 2 or something would be neat as i am not as good at making things concise like Scott!
Absolutely loved this episode. id love to see a BTS episode with all you research note and "distracted Tangent" stories you had while making this episode. Keep up the great work.
It blows my mind that we literally would have never figured out the excess heating of liquid hydrogen without quantum mechanics. It’s the only explanation that works and it just happened to be discovered less than 50 years before having lots of liquid hydrogen kicking around was a problem we needed to understand.
Hi Scott. One minor error, and that is that steam reforming requires pressurisation. This is not the case, as the reaction CH4 + 2 x H2O => 4 x H2 + CO2 works fine at atmospheric pressure at a temperature above 600C and Ni as a catalyst. You only need pressure when you try to get it to go in reverse... It is one of the reasons that solid oxide fuel cells can run on methane and steam and d not require highly purified hydrogen as fuel (as opposed to alkaline or polymer electrolyte fuel cells) as the SOFC can steam reform the methane internally directly in the anode (which is often made of nickel)
Scott, given the different propellant leaks in space in recent months...what happens to it? ...does it dissapear into molecules, coagulate into lumps, freeze? ...become effectively space shot gun blast for years? ...what are the risks to satellites?
Interesting question. Just giving what I know and my best guess...under extreme vacuum (such as in LEO) even a very cold substance will quickly sublimate and turn into a gas. So the propellants lost to space sort of just bop around at the molecular level, getting spread out over a large volume. The volume is so large that, in the end, you can sort of just think of them as 'disappearing'. A more technical answer would require me to look up what propellants were leaked exactly and what their phase diagrams are, but in general the above is 'good enough' for Kerbal work.
Many of these fuels and oxidizers can be seen made by many various different TH-cam channels that are chemistry based. All you have to do is look them up. I know that ReactiveChem, DBX Labs, Extractions & Ire, Explosions & Fire and Chemical Force all have done one or more of these and shown how they behave. Especially Chemical Force. Give them all a look at and watch their videos. You may even see my name in a few of them. 😃
Thank you for making a lot of my favorite content possible , or , at least easier to produce . If I still had a lab you would definitely have my business .
@@kaboom4679 hey, thanks for realizing what I do!!! I do try to help others with their projects as I feel we can all learn something new from them and it helps to let them have a sense of self satisfaction. That's what makes this business truly fun and exciting and makes it what it is today. I honestly can't imagine my life being any different now and I am extremely glad that I decided to do what I do now. I've made so many friends over the years and have been blessed with some of the best company and friends that a man can ask for and I am truly grateful for that and for the community helping out the way that they do. Now if only the rest of humanity can build a community such as the amateur chemistry community, maybe then we could all get along. 🙂
Great job as always. You might address solid sometime and/or talk about the challenges of storage and transportation of all these fun and funky liquids.
There is a company I visited that manufactures the catalyst for converting ortho to para hydrogen. It is iron based but good luck trying to make it! :)
When people ask “why should I care about quantum physics, isn’t it just propeller heads writing down equations?” I point them to semiconductors and the ortho-para hydrogen heating effect. :-)
@@Grak70 Wow, do people still say propeller heads? My favorite direct quantum effects in electronics: Hall effect sensors, Pelletier coolers, and of course, tunneling diodes.
@@Grak70 can add quantum dot displays as a common everyday application of quantum nanomaterials, theyre niche high end displays atm but they are about to be everywhere, QD-OLED and QD-mircroLED is gonna be a revolution in the high end that will likely take over most diplays.
When I was in high school in the 1960’s, we had a club where we experimented with rockets. At first, we built larger and larger rockets using commercially produced solid rocket motors. But, eventually we started building liquid fueled rocket engines, using K-1 kerosene and oxygen, eventually getting into liquid oxygen. We experimented with ammonia as well. Finally we built a liquid fueled engine that could burn hydrazine. Although we had tested that engine on ammonia and LOX and were able to obtain a few gallons of Hydrazine, we were never allowed to fly that rocket. The US Air Force found out what we were doing and said we could not fly it. But they offered to take the rocket to the White Sands missile range and test it. It was flown there and reached 110,000 ft and 125 miles down range, flying on hydrazine and liquid oxygen. Of the 4 of us who worked on this project, I’m the only one who didn’t go into aerospace engineering as an adult.
I'd always been curious about how it was made and you made it really easy to understand, outstanding work once again Scott! Also, thank you for teaching me to fly lol
@@darthkarl99, I was looking forward to seeing this comment! I was just looking over the Wikipedia article on chlorine trifluoride and Dr. Clark's quote about it being hypergolic with just about anything including " . . . cloth, wood and test engineers . . . asbestos, sand and water. . . . ."
@@johndemeritt3460 To quote the comments of Derek Lowes "Sand Won't Save You This Time" article on the stuff, the list of things it is flammable with should probably just be "Any Baryonic Matter".
@@darthkarl99 I'm glad someone else reads Derek Lowe's posts. Alas, he seems to have abandoned the "Things I Won't Work With" column. Or, possibly, he's run out of spectacularly unpleasant compounds to add to it.
@@christopherreed4723, don't worry -- more such compounds WILL come along: it's just that nobody's come up with the stupid idea of putting X and Y together yet. And with Artificial "Intelligence" coming into greater play every day, I have no doubt that AI is gonna come up with some real DOOZIES in the not-too-distant future!
I’ve watched this video twice now but I’m still not clear on how a plumbus is made. Where does the schleem come from and how fresh does the fleeb really need to be?
@@davisdf3064 In all seriousness, that’s the vibe I was getting while he was explaining how rocket fuel is made. It totally reminded me of the plumbus commercial, lol.
Excellent presentation. My knowledge of refining was just tripled in 15 minutes. Also hit topics I had forgotten like organic chemistry. I’d have to watch it again and take notes to pass the quiz, though.
Amazing video with a cool live chat while it premiered! Please schedule it next time so we don’t miss a thing! Now I’m going to watch it again a few times to properly understand everything said. 😅
Ignition!: An Informal History of Liquid Rocket Propellants by John Clarke is a great read for this sort of stuff. Executive summary:If it starts bubbling, run for the hills!
In the Ammonia diagram, it showed basically waste steam being bled out of the system, do they use that in conjunction with a turbine to generate electricity that could then be fed back into the system for the preheaters or compressors or would the added pressure cause problems and it is basically just wasted energy?
In a modern chemical plant, waste steam is fed into what’s called a “multiple effect” generator, where the low quality steam is used to preheat water or even lower quality steam to use up the temperature differential. So-called “triple effect” steam generation, where this trick is employed throughout the steam plant up to three times, are not uncommon in industry. Ultimately recovering this heat is limited by 1) the phase transition back to liquid and 2) the temperature differential you need to bridge, since more heat will flow if the counter-current streams have a large difference in temperature; at some point the capital and floor space won’t be worth getting that last bit of heat back.
Its so cool to have those kind of videos going very deep into what’s actually going on. Really cool to see everything i’ve learned so far in university like proton spin of hydrogen or joule Thompson effect etc sooo fascinating
Hello Scott, what a great explanation for something we usually take for granted. H2 production is not only a problem for the aerospace industry. Actually, it is a problem much closer to the earth - producing H2 to power hybrid and fuel cell buses for urban transport requires very complicated and expensive infrastructure.
Joule-Thomson is long outdated, because it's horrible inefficient. Turbo-expander to nearly liquefaction and the last few Kelvins by Joule-Thomson, to avoid turboexpander blade erosion damage from high speed droplet impacts is the way they do it nowadays. Unfortunately not easy to downscale, because turboexpander turbine needs to run at insane rpms due to Reynolds-number scale matching...
Well, I´m a chemical engineer, and basically, you just broke down the essentials of the different processes:
Mixing the chemicals according to the recipe, add catalyst as required (e.g. if an iron oxide catalyst in required, a rusty piece of junk from an old car will do the job, yet it will not be as effective as smaller particles with a good dispersion in the reactor, in other words: the reaction will take longer), set pressures and temperatures, give it some time for the chemistry to happen and proceed to downstream processing (rectification...).
On the process of steam reforming for hydrogen production: yes, it does release CO2, but burning fossile fuels to make electricity and use the electric energy to do water electrolysis would be less efficient, releasing even more CO2 than steam reforming itself.
The details of processing can be summarized as following:
- handling toxic chemicals (hydrazine) requires a vast amount of savety equipment: overengineered vessels and pipes, sensors to monitor unwanted releases, protective gear for the workers
- handling corrosive substances does require expensive materials that are able to withstand the corrosive stuff and savety equipment for the workers of course
- handling cryogenic substances requires loads of insulating materials, special lubricants, pumps and valves with extremely tight tolerances and protective gear, hydrogen production and storage in particular requires loads of sensors to detect hydrogen and special precautions to prevent the formation of an explosive mixture with oxidizers including plain air
- handling pressurized substances requires the vessels and pipes to be strong enough, which usually means beefy wall thickness of the vessels, piping and instrumentation.
The tricky part is to develop sensors for the different chemicals, that are sensitive enough to detect contaminations at a rather low level, but are insensitive for other stuff.
The rest (designing a plant that is save, from fire extinquishers to the girth of electrical wiring, from escape routes to ease of maintainance) is a matter of experience that has been accumalated over the last century and is appied on any chemical plant to a certain extend, as required by local laws and regulations.
So yes, when you look into the details, it gets complicated very soon, but that is exactly why there are experts like engineers after all:
Anyone can build a hut from branches that were cut from trees, but it requires lots of knowledge to build a skyscraper people enjoy living in.
Last but not least: Yet another great video for those that are interested in rocket science.
Two thumbs up, Scott!
1000% There is so much engineering that goes into our life that 99% of people dismiss. And this is just the rocket science... (and just the propellent side)- which there are people posting, from their smart phones, that "spaceflight is a waste of money". Yes, you can post the "waste of money" from your phone... only **because of spaceflight**!
Thank you for posting the conundrum of processes that happen in this industry!
"On the process of steam reforming for hydrogen production: yes, it does release CO2, but burning fossile fuels to make electricity and use the electric energy to do water electrolysis would be less efficient, releasing even more CO2 than steam reforming itself. "
On the other hand, using other means to produce electricity, such as solar or nuclear, would make hydrogen production much cleaner.
I'm a chemist and if I can make two grams with 30% yield, over three days from reagent grade starting materials without poisoning myself I'm happy. Very much harder to run an industrial process and I am very impressed by chemical engineers' ability to make useable quantities in reasonable times with sustainable economics and enough safety for workers to stay safe.
does kind of make it easy to understand why RP-1 is so popular for rocketry on a budget though, From the ground side of handling it there is no exotic requirements.
the main thing I know about chemical reactions at the industrial scale is temperature control is a huge thing, As from watching videos on the USCSB channel. Some reactions get very perky if they have an excursion from their intended temperature range.
@@kangirigungi You´re absolutely right, electrolysis can easily done from electric energy from renewable or nuclear scources. But on a global scale, nuclear and renewable energy is less than 20 % of the energy mix and electrolysis is more expensive than steam reforming. Additionally, the vast majority of the hydrogen produced globally is used in refineries anyway, so the rescources for steam reforming are already on site.
Scott, I as a PhD chemist, am impressed how layman-y you managed to make all the process sound. If I had to explain all to a layperson I could NOT be able to simplify all so much, yet I think you managed to keep pretty much all chemically accurate yet clear to a non-expert. You even got the parahydrogen thingy accurate. Bravo, from someone with a PhD from a top-A-tier university in the US. You are a great science communicator
one minute point I would have made at the end is that all these chemical steps pile up such that at the end you pretty much compress as much chemical energy you can in a certain mass/volume so it can become rocket-relevant. all those steps are like walking up a stairway, and after you do it enough, you reach the top of the Empire State Building, ready to release the potential energy you stockpiled. you kinda need the chemical equivalent of that for rocket fuels.
I am a chemist, retired now, and you did an excellent job of summarizing for the non-chemists how these rocket fules are made.
The chemistry is well known and the really hard part of making rocket fuels is not the chemistry, it is the chemical engineering, the mechanics if you will, for . Your diagrams and explinations did a great job of explaining what the fuels are and how the mechanicl processes work.
I’m a retired chemist too and I wholly agree with what you wrote.
Do you mean that the hard part is the scaling it up? Making it as efficient as possible, etc? What are the hardest ones?
@@kindlinProbably more about the efficient mass production, piping (pressures/wall thickness), thermal insulation, tolerances, (with hydrogen especially) sealing, etc.
You want to use corrosive agents? That requires other materials to make it work than for example dealing with hydrogen - an atom so small it doesn't want to stay contained.
All the safety regulations and equipment are disregarded for the sake of keeping the text wall a bit shorter.
In other words, just like with rocket science - the science is easy and mostly done, it's the engineering that gets you.
DEVIL,S VENOM!
4:40 The hydrotreating happens AFTER fractionation. Then, you fractionate a second time to eliminate the light ends which are typically produced from hydrogenating molecules like sulfides (R-S-R' + 2.H2 -> H2S + R-H + R'-H) or thiols (R-SH + H2 -> R-H + H2S) and from the inevitable cracking of a part of the feedstock (few % typ.). If you want a precise cut, you may also want to cut the bottom at high reflux, to eliminate heavy ends that were either created by the odd polymerization (very small fraction
I appreciate your corrections.
I think you meant ped^H^H^H^H chemistry. After all, consider your audience. And if anyone says "OK boomer" to you for using "^H^H^H^H" to mean 4*backspace, hit them with your cane!
disclaimer: This message written on a VT100.
@@thekinginyellow1744 Ah, I see, you are one of those who remember the last August :P
@@thekinginyellow1744 Why are you using four backspaces when "ped" only has three letters?
@@Anvilshock Because I was too lazy to type them and just cut and pasted from the OP. Isn't that how most egregious errors are introduced into text documents?
Man even your way in explaining chemistry is so clear, we can't thank you enough.
What did he explain though? He said mix this with that and presto! That's not an explanation lol, that's Five Minute Crafts Chemistry Edition
For a moment I thought NASA pulled up
@@dziban303 didnt even mention valence, and now a bunch of people think they understand something they have no clue of XD.
Even saw one idiot questioning if college was a good idea if it could be explained in 5 minutes lmao
I thought NASA actually commented on this vid 😂
If he was a professor I would love to be in his class
Small correction: it is the nuclear (proton) spins that distinguish the para and ortho forms of H2, not the atomic spins which usually refers to the electron spin. In the H2 molecule the electron spins are in a spin singlet, it is the total spin of the two protons that distinguishes the two spin isomers.
I should have explained this better.
Small mistake at 15:27, you combine two ammonia molecules, not atoms. Yes, I noticed because I got a B.S in Chemistry...
Great reference to John D.Clark's Ignition! It is an absolutely fascinating read (though a bit technical at times for non-chemists, I presume). The gist of it is that it's not really difficult to synthesize some of these things, but handling is an entirely other matter
Right! Clark could have named his humorous "informal history" BOOM! (which is not what you want in a propellent). I agree with your assessment of his book. He keeps the chemistry concise. Those of us with any interest in reading his book usually have the know-how. John Clark is an important figure who's personal stories are historically important.
Making me think a lot about Ignition! An informal history of liquid rocket propellants by John D Clarke. Fantastic read and fun video!
Oh liquid rocket pooo juice and hair to glue to Scotts head god bless you for thinking about ignition and god bless history and propellants of ahri
What is really impressive about Dr. Clark is that, in all his years working with substances that were (to paraphrase the introduction) explosive, corrosive, or mind-blowingly toxic, and often all three at once, his working group did not suffer a single time-lost incident. He must have been, for all his wit and humor, an absolute tyrant about proper safety procedures.
@@christopherreed4723 There were a few explosions though. He must have had backup equipment/facilities standing by.
This book is amazing
That's a great book! And funny too 😆
I took a year of organic chemistry in college. I almost understood what you just said. Very impressive. 👍
wish I had two semesters of college organic chemistry under my belt!
If this was more educational than your classroom time, I’m wondering whether free taxpayer funded college is a good idea 🫢
I was a chemistry major until I got to O-chem. Immediately changed my major to history that semester!
@@kamakaziozzie3038 lol, your dunning kruger is showing. Organic Chem is one of the broadest and most important subjects, it describes virtually all the processes of life and most of the processes of industry. This is so grossly over-simplified he never even mentions valence or electron shells or bond energies or angles, all the things you use to figure out how to make a reaction happen (and what you made).
Also - what kind of idiot doesnt see the value in a more productive and capable workforce, if not the societal value of a world that isnt full of morons?
@kamakaziozzie3038 an older gentleman anecdotally forgetting something he learned years ago? obviously proves those libs wrong😂😂😂
@@kamakaziozzie3038 >>If this was more educational than your classroom time
Thank you for explaining all this Scott!
At our integrated Steel Factory we have several Linde Gas Air separation plants, supplying us with mainly Oxygen for several production processes.
Big tanks of LOX, LN2 and Argon, also transported off site to other Linde Gas customers in the food industry.
We also have big pressure tanks for fire suppression in certain areas, filled with either Argon or the latest Argonite A2N2 mixture.
Smarter everyday! 😉
And who do you think an early developer of these gas - liquid transitions was? Hint: Look at the name on your building. 😄
@@janetizzy6741 that's why I mentioned it 😂
And Linde Gas is a separate company wist several factories on our site 😉
Ph.D. chemist here. Pretty good explanation!
The hard parts of these processes are the exact pressure, temperatures, catalysts, and equipment used to run them. Almost all of which are industrial secrets, patented, or a mix. So if you somehow had more details to share, you’d probably get some strongly-worded letters from attorneys. Best to let them keep their secrets.
No, that mindset also holds back advancement which can't be made in that type of atmosphere. all we need is retired people to share data which they always do also isn't there a version of this that you learn by just knowing chemistry basically.
@@johnk7302 Doing things on a small scale has some significant differences to large scale, there are unique challanges imposed with mixing and temperature control and every company has it's own methods of dealing with the issues.
@@johnk7302you are not going to discover 21st century transition metal catalysis in your garage hobby lab.
Patented details cannot be kept secret, that's the point of the patent process: A time limited monopoly in exchange for revealing your industrial secret for the competitors to duplicate the moment the time is up.
"Alright then, keep your secrets" - Frodo Baggins to Gandalf the Grey
The hydrazine synthesis sends chills down my spine. NaOCl and ammonia easily gives you NCl3, an absolutely terrifying explosive. I don't want to know how many injuries were incured to dial in the process parameters to make it work.
it also gives you what's basically chlorine gas, as in the WW1 chemical weapon.
And it gives you hydrazine, an incredibly toxic, carcinogenic, and inflammable chemical 😁
@@danielkorladis7869 Chlorine gas is relatively easily handled and detected and has a characteristic smell, therefore not the worst occupational hazard. An extremely shock and light sensitive explosive that may pool somewhere on the other hand...
@@wilfriedklaebe but totally awesome for the astroneer fans. only question, does it come in pink?
@@danielkorladis7869 This is a common misunderstanding: The reason you don't mix ammonia (NH3) and bleach (NaOCl) is because it forms chloramines, which tend to be strong irritants, particularly NCl3. And no, this is not the same as mustard gas, as some like to claim.
For chlorine gas to form, the bleach would have to react with acid.
But yeah, NCl3 is plenty nasty on its own. In the early 20th century, it was used as a flour bleaching agent, and there is a hypothesis that overuse of NCl3 caused a mass psychosis incident in the French Village of Point-Saint-Esprit (this is a fascinating rabbit hole to go down, btw) by oxidizing the proteins in their flour into neurotoxins.
I worked in a cryogenic production plant in the US Air Force many years ago. We produced liquid oxygen and liquid nitrogen. The two are separated through distillation. It's basically the compression of air then the expansion, either through an expansion valve (high pressure plant) or through a turbo expander (low pressure plant). The now liquid air was directed to a distillation tower where the heavier oxygen settled in the bottom and the nitrogen on top.
You forgot about the solid fuels. They're pretty interesting as well.
He did a full vid for SRBs
At PEPCON in Henderson, Nevada it got REALLY interesting that one time!
@@macmedic892 no.
@@ananttiwari1337 In the sense of the Chinese curse "may you live in interesting times", yes, it did.
Yes! Can we have another video on the solid fuels please 🙏 Scott? 😁
All my post-high-school chemistry education comes from the "Things I Won't Work With" blog, which sure makes learning about chemistry fun!
I agree. I enjoy that entire blog. My favorite is, Sand Won't Save You This Time.
As a comp sci guy who during childhood wanted to be a chemical engineer I'm in awe of you guys. Fucking amazing
@@BacklTrack As a neuroscientist (retired), I'm also in awe of engineers, especially chemical (and electrical). I couldn't handle the math, let alone the theory, let alone the creativity required to employ the vast body of human knowledge in novel ways. Scientists generate knowledge. Engineers figure out what to do with that knowledge, which I think is far more challenging. I think the easier part of their job is telling the scientists what we got wrong.
never thought H2 would have an ortho or para allignment state, i only ever thought things with larger structure could have different alignments
Does that mean it's basically down to quantum physics? Would be interesting if this effect was known before quantum theory was released.
It was observed in 1910s and proposed different molecular types/states for H. Later, in 1920s they were first produced separately.
Quantum mechanics formed in late 1920s, Heisenberg got his Nobel for it in 1932
And this theory momentarily explained, what was happening with molecular hydrogen
@@benjaminhanke79 a bit from my memory higher in thread. Missclicked answer, so didn't tag you)
H2 is weird. It can also leak through solid metal while making it weaker because it's so tiny.
@@guillermotorres6376 what you speak about are two slightly different processes
But yes, lightest element is very weird
Honestly, something that never ceases to amaze me is just how much chemical engineering has to go into different colors of dyes and paints.
Chemistry student here: It is relatively easy to synthesise things like Hydrazine on a large scale. The hard part was getting there, and optimising the process. And the challenge of keeping the production affordable in the face of economic factors.
And not getting blown up or coroded away in the process ;)
You explained the chemistry really well. There are a lot of little things to do and get right for every different type of chemical reaction. For this type of video and audience it would be way too much to get into that level of detail.
Can you point to someone that can get more into the details? I’m genuinely interested in chemistry and videos help a lot. Not the last few, as I know their decomposition compounds and enjoy living, but distilling hydrocarbons sounds like a cool process, as well as chilling air to the tens of kelvin instead of hundreds.
@@theinsane4469Here's a handful of youtubers that cover chemistry
Some more than others.
youtube.com/@NileRed
youtube.com/@NileBlue
youtube.com/@NurdRage
youtube.com/@DougsLab
youtube.com/@Chemiolis
youtube.com/@ExtractionsAndIre
youtube.com/@ExplosionsAndFire
youtube.com/@theCodyReeder
youtube.com/@codysblab4771
@@theinsane4469 Nile Red/Nile Blue is a good place to start.
@@mycosys Wait, "Nile Blue" isn't that a parody?
@@benjaminhanke79 no that is nile green(mrgreen), but i think he making he own videos now, stil a madmann cemist
I'm so glad I found your channel.
Your delivery is amazing, its light and breezy not preachy and boring.
You take complicated topics and brake them down into easily digested chunks.
I wish you all the best with the channel.
Hi Scott, chemist here. You have explained it rather nicely without going into specific details.
I am glad that chemical industry gets its fair share of appreciation because we tend to get only more than fair share of cancer.
Heyy! I made some Hydrazine and NTO for my High School Chemistry project a few months back!
Primarily used Raschig process for the hydrazine and fuming Nitric acid for the NTO. It was super fun to see the reaction!!!
The hard part was preparing the NaOCl, because the ones we use in pools are calcium. Had to work literally on Ice with an ice bath all the way, but it was definitely worth it to see the flames!
did you make it by the chloramine process or the hofman degradation with urea?
With chloramine and ammonia, the same process he describes in the vid. But I’d say the hardest part was preparing the chloramine itself…
One of my most loved books is a copy of “Rocket Power And Space Flight” by G. Harry Stine from 1957. He was one of the researchers at White Sands doing some of the early research with the Aerobee and Nike rockets. It has incredibly interesting breakdowns of what they were doing with fuels and cycles at that time and it’s interesting how little the fundamentals have changed.
I work with the cryogenic stuff daily. Though cooling the liquid oxygen might increase its density a bit, I would think its main advantage would be that they have a better margin from the oxygen temperature in the tank to its boiling point. Together with a further pressurization of the tank this is supposed to prevent cavitation of the oxygen liquid in the turbopumps during flight, which is really bad. So the cooling serves as a security measure as well and gets them more time of usable oxygen.
I believe the advantage of using sub-cooled oxygen is principally due to its higher density. Temperature margin might be a factor as well but whenever I've read about the use or planned use of sub-cooled or slush cryogenic propellants, the focus is always on their higher densities and what effect it has on rocket performance.
I can make Lox on my own if I can find an essential component LN2😖...cryogenic liquids are a pain to find
I'm a medical student that has been watching since KSP 1 was near early-access launch! Great explanations! I appreciate all you do!
Great video ! I wish someone could explain me this when I was in highschool. It would make me more prone to learn chemistry.
Hydrazine can be used as a monopropellant - expose it to a catalyst and it will spontaneously and energetically decompose. There are some emergency systems that depend on this arrangement in case of power loss for a critical application where the hydrazine is released across a catalyst and the decomposition products are fed into a turbine tied to an electric generator. Doesn't last very long -- for those critical applications - deemed long enough.
All those reactions use cheap catalysts, like pure iron, or iron oxide. However they also need those catalysts to be ultra pure, so the iron used to make them has to be specially refined, to remove all of the other metal contaminants that normally are added to improve strength and ductility, as they can also act as catalysts and make unwanted side reactions.
Excellent stuff. As to complications, there's always a lot hidden behind the simple statements of "at pressure" and "at temperature". Just ask those Fusion physicists.
This is the kind of think I'd love to see a wiki for; the nitty-gritty of how these really work with enough details that someone with access to the right catalogs and enough money could set up production. (And where someone who reads the warnings section can run it without losing any fingers, friends or family.)
What would be totally cool would be to try to expand that all the way to a "tech tree for the real world: everything you need to know to build Starship starting from picking up stuff off the ground and identifying it".
As a chemist, this is a useful summary, especially since most of us who don't work in these kinds of bulk chemical industries don't necessarily know much about routes to basic chemicals like hydrazine! I've used hydrazine hydrate a few times (a lot less scary than the anhydrous stuff) but never really thought about how it is made!
Chemistry seems to alway go over my head, but this simplified things a bit for me. Amazing how some of these processes create interesting byproducts, like salt and water!
Ready Salted Hydrazine! An exciting new flavor, not suitable for human consumption. Not something I'd ever want to work with though, as quite a few early rocket fuel pioneers discovered.
@@brolohalflemming7042 just watching, I got chills…
I’m certainly no chemist, but I understand the basics. I know what most of those fuels break down into and I definitely wouldn’t want to experience that experiment…
Being more of a history nerd myself, I have read quite a few account of labs exploding purely because of the reactants and decomposition compounds. Exciting stuff, but only to read about…
I'm no chemist, but I play one at home. Stable compounds like salt and water are often used to crowbar more unstable compounds into existence. When you mix some molecules whose constituents like to form salt and/or water, but there are some atoms left over after, those have no choice but to form a compound themselves.
The calcium carbide to acetylene reaction is a good example, though somewhat reversed. Calcium carbide really really wants to form calcium hydroxide, so it'll tear apart water molecules to get to the OH. The remaining hydrogen and carbon forms energetic C2H2.
Sulfuric acid catalyzes many reactions that form water, by grabbing onto the formed water so it can't dilute or balance out the reaction. Sulfuric acid is famously grabby towards water - maybe you've seen the demonstration of if tearing water out of sugar, leaving a carbon foam.
@@galfisk Yep. When I was at school, I condsidered ia careeer in chemistry, but switched to engineering instead. And learned a healthy respect for MSDS and safety lables. The Internet has been great for reinforcing that message. I think military and rocketry chemistry is one of those delicate tightropes to walk. You want to create an energetic compound, but you also really want it to be stable enough to store, handle, force through turbopumps etc. Or simple hypergolic fuels that'll happily rapidly oxidise anything organic, including pilots and fuel handlers. Or the great 'Things I'll never work with' blog. We're carbon-based life forms, but can be un-lifed by a few C-N molecules. Or faster if you force a dozen C-N bonds into a molecule and look at it funny. It's one of those subjects I'm content to learn about from a very safe distance!
Yeah I found it pretty funny that such a toxic chemical would have such innocuous byproducts hahaha!
A couple years ago I picked up a copy of Ignition! by John D Clark. The shit these guys were getting up to in the 40's and through the Cold War was just nuts.
i laughed for a solid 10 minutes at the part about CTF
Another fantastic video. Perfect!
I have yet to see such a succinct and non-patronising science video maker/educator.
I read Ignition on your recommendation. If you'd mentioned the power of the nitrogen bond it'd be legendary.
Noone was more surprised than me when I passed o-level chemistry, much prefer physics, but I understood that presentation. Thanks Scott.
You may not be a chemist but you made it a lot easier and much more interesting than my chemistry teachers did.
....... by not mentioning any of the chemistry lol
@@mycosys Are you disappointed by Scott's video?
@@General12th No, he just mentioned how it's simpler than a lot of chemistry classes. Scott's video still explains the concept nicely and simply considering the topic, but chemistry classes often have to get into the far more nitty-gritty details so you can recreate it in the lab yourself.
If you haven't read the book Ignition then you should. It's and interesting and funny history of rocket fuels.
I love these types is Scott Manley videos 👏
..and pretty much every other type
His nuclear series is among the best on TH-cam
Excellent Video, Scott, especially for non-chemists like me. Also would be great to know toxicity, handling, and transport issues.
I mean sure, it isn't as easy as you described it. But everything is correct, and it's super understandable!
Props for breaking down a difficult topic like this so successfully!
This video adds a great perspective that we often miss, just as how we often look at the design of a rocket as the challenging part where, in reality the manufacturing is the greatest work. Same with the Fuel apparently.
When I heard bleach + amonia I thought "are you crazy? That's incredible dangerous "(you can actually die because of that if you mishandle cleaning products). Then I remember you were talking about hydrazine. I know people use special suits to even come close to a hydrazine source.
yeah, everything I've heard about hydrazine, including this, convinces me it's one of the worst substances in the world
@@danielkorladis7869 dimethyl Mercury is worse. A few drops even with a latex glove and you die months later. And it was thought as rocket fuel although never actually tested.
Incredibly dangerous is the name of the game when you're talking about rocket fuel lol
@@GODDAMNLETMEJOIN ethanol(unless you add something to discourage drinking) is safe. I can't think of a safe oxidizer though.
@@guillermotorres6376
It's a nasty fire Hazzard once you distill it to rocket fuel grade; see how long you last smoking at a distillery.
Clark’s book “Ignition” is an entertaining and informative look into the development of rocket fuels.
I once made solid rocket fuel from potassium nitrate and sugar at home on a gas stove. That was stupid. Don't ever do it.
Yep, a hot plate would be better.
I tried with sodium nitrate, and it didn't work...
Curious to what happened to make it such a stupid idea?
I decline to incriminate myself by contributing to this conversation...
@@jamalalkaabi8 thinking probably the white hot fire shooting out of a kitchen pan when it got a little too hot.
Very cool Scott. I work in a chemical plant that produces Ethen (Ethylene), which we use to produce polyethylene. You did a great job explaining this subject and how the same processes are used to produce rocket Fuel.
I liked the fact that you used CamelCase in the chemical's names. Makes them way easier to read and understand, and I think that should be standard.
Actually, that is PascalCase 🙂
Make it sound easy? By the time you got to the beginning of hydrazine my head was already spinning, need rewatch few times to grasp. Thanks for tasty knowledge Scott!
I love "Ignition" by John D. Clark beause of the cool stories behind developing the extreme chemicals in the early days of extreme rockets. Not an easy read though...
I've not been a chemist for a few years now but that was an excellent explanation. Most of the reactions here are not what your average everyday lab chemist would do. They either produce things that you'd just buy or things that are too dangerous for day to day work, looking at you hydrazine. Saying that though all the reactions are well understood, the real difficulty is in the engineering and producing them safely at scale.
yey! Finally an Old School Scott Manley video!
Chemist here. It's not quite as easy as you said! :P But, joking aside, the video is great. Of course you couldn't get into the details of chemical processes, but you gave an excellent high level overview. Thank you!
I can make Lox on my own if I can find an essential component LN2😖...cryogenic liquids are a pain to find
@@QuantumDoze They're easy to find. The problem is more that they're hard to find in reasonably small quantities. If you call Linde or AIr Liquide and order a tank truck of LN2 they'll be over at your place tomorow morning and will probably throw in a complementary dewar. But if you try and order just one or two dewars they'll likely laugh and hang up on you.
I am engineer for NASA and SpaceX and Blue Origin I am also a chemical doctor and nobel prize winner and fellow at MIT. This is the greatest explaination of rocket fuels available in the history of mankind!
There is a quite funny book on the history of rocket fuels “ ignition” by John d Clarke, it doesn’t go so much into chemistry but the race about who was going to mix this with that and not blow themselves up is quite humorous.
Hi Scott…. There’s a book, “Ignition!: An Informal History of Liquid Rocket Propellants” by John Clark. A first person narrative on the development and often dangerous experimentation of all manner of liquid rocket fuels. Very entertaining, extremely informative, and rather humorous. Highly recommended…
I think you mean it is a guide to start your pre-emissions car or truck 😁
Check out Scott's video "The most dangerous rocket fuels ever tested." Scott has a copy of the book, and he references some of the humorous sections in the video.
@@matd675 yeah, I was going to say that I first heard about that book from this channel, but perhaps it was xkcd. There are a few incorrect diagrams in the new reprint, but it's an enjoyable read.
The text he highlighted about sailors drinking the ethanol fuel is from Ignition.
I wish all my school teachers from the 80's explained things this well. I would have achieved a string of distinctions.......Thank you Scott
I'm a chemist by education, if not by trade, so I can't speak to the engineering challenges, but I thought you did a great job with an overview of the chemistry.
Regarding the Linde process: Nowadays you use turbines for the decompression step to get rid of the energy in the gas, not a throttle valve and you also use a similar fraction column as an oil refinery.
Yeah that’s the Claude process
Student giving the teacher some pointers
The distinction between the Claude process and the Lindie process is an important one.
Cooling with throttling expansion is very inefficient because all of the energy stored in the compressed gas shows up as friction heating of the throttle valve.
When you make that gas do external work as it expands it ends up far colder for a given pressure difference.
Jon
Great topic, and good summary. It does remind me why I found reading Ignition! such a chore. All that chemistry... )))
Angel's petrochem mod for Factorio taught me more than I thought!
This is a great video! Though, it does seem like a prime candidate for splitting into chapters by using some timecodes in the description. I think these are right:
00:00 Introduction
01:27 Ethanol
02:42 RP-1
05:05 Methane
05:59 Liquid Oxygen
08:44 Liquid Hydrogen
12:04 Chemical plant introduction
12:45 Hydrogen peroxide
13:34 Ammonia
14:25 Nitrogen tetroxide
15:13 Hydrazine
16:53 Wrapping up, fly safe
thankyou Scott ive been holding on a long time hoping you do a series on fuel production and the chemistry behind it awesome work
I'm one of those Chemists out there. You did a pretty good job. Yes it's always more complicated, but you made no glaring mistakes that I would criticise.
Really good video (ex proces engineer), esp about LH2
I would love to see a collab follow up to this with NileRed and have you both talk about how to make a simple hypergolic rocket engine
Maybe ask Integza to join too...
furfur alcohol and inhibited red fuming nitric acid is the easiest hypergolic fuel combo ive found
I like that red dye is added to RP-1 so you don't have to pay road taxes on it... =b
Would it not be less pure then?
The red dye also likely doesn’t contribute to ΔV.
2 months ago
Man even your way in explaining chemistry is so clear, we can't thank you enough
RageDavis
2 months ago (edited)
Well, I´m a chemical engineer, and basically, you just broke down the essentials of the different processes:
Mixing the chemicals according to the recipe, add catalyst as required (e.g. if an iron oxide catalyst in required, a rusty piece of junk from an old car will do the job, yet it will not be as effective as smaller particels with a good dispersion in the reactor, in other words: the reaction will take longer), set pressures and temperatures, give it some time for the chemistry to happen and proceed to downstream processing (rectification...).
On the process of steam reforming for hydrogen production: yes, it does release CO2, but burning fossile fuels to make electricity and use the electric energy to do water electrolysis would be less efficient, releasing even more CO2 than steam reforming itself.
The details of processing can be summarized as following:
- handling toxic chemicals (hydrazine) requires a vast amount of savety equipment: overengineered vessels and pipes, sensors to monitor unwanted releases, protective gear for the workers
- handling corrosive substances does require expensive materials that are able to withstand the corrosive stuff and savety equipment for the workers of course
- handling cryogenic substances requires loads of insulating materials, special lubricants, pumps and valves with extremely tight tolerances and protective gear, hydrogen production and storage in particular requires loads of sensors to detect hydrogen and special precautions to prevent the formation of an explosive mixture with oxidizers including plain air
- handling pressurized substances requires the vessels and pipes to be strong enough, which usually means beefy wall thickness of the vessels, piping and instrumentation.
The tricky part is to develop sensors for the different chemicals, that are sensitive enough to detect contaminations at a rather low level, but are insensitive for other stuff.
The rest (designing a plant that is save, from fire extinquishers to the girth of electrical wiring, from escape routes to ease of maintainance) is a matter of experience that has been accumalated over the last century and is appied on any chemical plant to a certain extend, as required by local laws and regulations.
So yes, when you look into the details, it gets complicated very soon, but that is exactly why there are experts like engineers after all:
Anyone can build a hut from branches that were cut from trees, but it requires lots of knowledge to build a skyscraper people enjoy living in.
Last but not least: Yet another great video for those that are interested in rocket science.
Two thumbs up, Scott!
This video made me realize that steam reforming of methane to get hydrogen is basically the Sabatier process in reverse.
I guess it’s the temperature that drives the equilibrium in on direction or the other.
I'm a chemist and I think you did a phenomenal job explaining it.
Reminds me of when I read "Ignition" by John Clark. To paraphrase: "It was a good day when we didn't blow up the lab. It was a better day when we DID blow up the lab." (for science)
I made a number of rocket fuels as a teenager back when you could ask your local pharmacist for the ingredients and nobody batted an eyelid. However, I couldn't find any recipes, so working on the idea that the difference between an explosive compound and solid rocket fuel was the rate of oxidation, I went to the local University library, found a book on explosives, copied down the formulae (I didn't know what the formulae meant so I treated them as proportions) and went home. Some burned, some didn't, but the only one that burned furiously enough to power a rocket but not explode was wasted and I never got the chance to make the rocket with it. Here's why:
Rather than paying attention to my chemistry classes, I used the school's glassware to mix my fuels. I had just finished one with, I think from bad memory, potassium permanganate and carbon black? I left it in a petrie dish on the bench. There is always one idiot classmate, isn't there? He went up to it with a box of matches and voila! the chem lab lacked curtains, and I was asked not to do any more chemistry. And what was worse, I hadn't written down the manufacturing process. Of course it was the 70s, so I didn't get a visit from any spy agencies...
Granted it may not be as relevant to rocketry as it is to sustainable (bio-) fuel, but Dimethyl Ether is neat! Covering that and maybe nitric acids would be cool (at least in my biased opinion)
Also i don’t know the theoretical ISP (it may be quite poor) but given the simplicity of Pressure Fed Designs, a DME-Nitrous Oxide Rocket would be a neat storable pressure fed rocket! Kind of similar to that Propane rocket design you mentioned some company was working on (although bio/syn *proper* propane is far mor difficult to make than similarly stored DME)
Ether is always a winner
@@hicknopunk Ah, devil Ether... it makes you behave like the village drunk in some early Irish novel. I knew we'd be into that rotten stuff soon enough.
Nitric acid is basically nitrogen dioxide mixed with water and ether takes ethanol as a basis and doing an acid catalyzed displacement.
I have the impression that those fules are not as prevalent anymore, probably why the ave been left out.
@@cahdoge You are thinking of Ethyl Ether probably, not Dimethyl Ether ;)
But yeah I’ve read up a bit on Nitric Acid too, although I think it being covered in a part 2 or something would be neat as i am not as good at making things concise like Scott!
Absolutely loved this episode.
id love to see a BTS episode with all you research note and "distracted Tangent" stories you had while making this episode.
Keep up the great work.
The explanation why it's so difficult to use hydrogen is magical. Quantum mechanics made manifest.
It blows my mind that we literally would have never figured out the excess heating of liquid hydrogen without quantum mechanics. It’s the only explanation that works and it just happened to be discovered less than 50 years before having lots of liquid hydrogen kicking around was a problem we needed to understand.
Hi Scott.
One minor error, and that is that steam reforming requires pressurisation.
This is not the case, as the reaction CH4 + 2 x H2O => 4 x H2 + CO2 works fine at atmospheric pressure at a temperature above 600C and Ni as a catalyst. You only need pressure when you try to get it to go in reverse...
It is one of the reasons that solid oxide fuel cells can run on methane and steam and d not require highly purified hydrogen as fuel (as opposed to alkaline or polymer electrolyte fuel cells) as the SOFC can steam reform the methane internally directly in the anode (which is often made of nickel)
Scott, given the different propellant leaks in space in recent months...what happens to it? ...does it dissapear into molecules, coagulate into lumps, freeze? ...become effectively space shot gun blast for years? ...what are the risks to satellites?
Interesting question. Just giving what I know and my best guess...under extreme vacuum (such as in LEO) even a very cold substance will quickly sublimate and turn into a gas. So the propellants lost to space sort of just bop around at the molecular level, getting spread out over a large volume. The volume is so large that, in the end, you can sort of just think of them as 'disappearing'.
A more technical answer would require me to look up what propellants were leaked exactly and what their phase diagrams are, but in general the above is 'good enough' for Kerbal work.
I'd say it strongly depends on which type of propellant you're talking about.
@Ricahrd Bean What's leaking at the ISS is coolant not propellant but same thing as J V says
I'm no chemist so most of this video went over my head. Still, it was interesting. Thank you for sharing. Have a great day and stay safe.🙂🙂
Many of these fuels and oxidizers can be seen made by many various different TH-cam channels that are chemistry based. All you have to do is look them up. I know that ReactiveChem, DBX Labs, Extractions & Ire, Explosions & Fire and Chemical Force all have done one or more of these and shown how they behave. Especially Chemical Force. Give them all a look at and watch their videos. You may even see my name in a few of them. 😃
Thank you for making a lot of my favorite content possible , or , at least easier to produce .
If I still had a lab you would definitely have my business .
@@kaboom4679 hey, thanks for realizing what I do!!! I do try to help others with their projects as I feel we can all learn something new from them and it helps to let them have a sense of self satisfaction. That's what makes this business truly fun and exciting and makes it what it is today. I honestly can't imagine my life being any different now and I am extremely glad that I decided to do what I do now. I've made so many friends over the years and have been blessed with some of the best company and friends that a man can ask for and I am truly grateful for that and for the community helping out the way that they do. Now if only the rest of humanity can build a community such as the amateur chemistry community, maybe then we could all get along. 🙂
Great job as always. You might address solid sometime and/or talk about the challenges of storage and transportation of all these fun and funky liquids.
There is a company I visited that manufactures the catalyst for converting ortho to para hydrogen. It is iron based but good luck trying to make it! :)
When people ask “why should I care about quantum physics, isn’t it just propeller heads writing down equations?” I point them to semiconductors and the ortho-para hydrogen heating effect. :-)
@@Grak70 Wow, do people still say propeller heads? My favorite direct quantum effects in electronics: Hall effect sensors, Pelletier coolers, and of course, tunneling diodes.
@@RossReedstrom I guess I’m old!
@@Grak70 can add quantum dot displays as a common everyday application of quantum nanomaterials, theyre niche high end displays atm but they are about to be everywhere, QD-OLED and QD-mircroLED is gonna be a revolution in the high end that will likely take over most diplays.
When I was in high school in the 1960’s, we had a club where we experimented with rockets. At first, we built larger and larger rockets using commercially produced solid rocket motors. But, eventually we started building liquid fueled rocket engines, using K-1 kerosene and oxygen, eventually getting into liquid oxygen.
We experimented with ammonia as well. Finally we built a liquid fueled engine that could burn hydrazine. Although we had tested that engine on ammonia and LOX and were able to obtain a few gallons of Hydrazine, we were never allowed to fly that rocket. The US Air Force found out what we were doing and said we could not fly it. But they offered to take the rocket to the White Sands missile range and test it.
It was flown there and reached 110,000 ft and 125 miles down range, flying on hydrazine and liquid oxygen.
Of the 4 of us who worked on this project, I’m the only one who didn’t go into aerospace engineering as an adult.
I'd always been curious about how it was made and you made it really easy to understand, outstanding work once again Scott!
Also, thank you for teaching me to fly lol
I'm just glad I can still just about keep up with the chemistry enough to get the gist! A talented teacher makes the difference I think. Cheers
How do you make rocket fuel?
Very, very carefully. And, if possible, while wearing a good pair of running shoes.
Someone's been reading about chlorine trifluoride.
@@darthkarl99, I was looking forward to seeing this comment! I was just looking over the Wikipedia article on chlorine trifluoride and Dr. Clark's quote about it being hypergolic with just about anything including " . . . cloth, wood and test engineers . . . asbestos, sand and water. . . . ."
@@johndemeritt3460 To quote the comments of Derek Lowes "Sand Won't Save You This Time" article on the stuff, the list of things it is flammable with should probably just be "Any Baryonic Matter".
@@darthkarl99 I'm glad someone else reads Derek Lowe's posts. Alas, he seems to have abandoned the "Things I Won't Work With" column. Or, possibly, he's run out of spectacularly unpleasant compounds to add to it.
@@christopherreed4723, don't worry -- more such compounds WILL come along: it's just that nobody's come up with the stupid idea of putting X and Y together yet.
And with Artificial "Intelligence" coming into greater play every day, I have no doubt that AI is gonna come up with some real DOOZIES in the not-too-distant future!
Thanks for steps on how to make hydrazine! Will be trying it in my backyard today
I’ve watched this video twice now but I’m still not clear on how a plumbus is made. Where does the schleem come from and how fresh does the fleeb really need to be?
That depends on how flagrant the schwuck is.
I think you are in the wrong interdimensional TV channel
@@davisdf3064 In all seriousness, that’s the vibe I was getting while he was explaining how rocket fuel is made. It totally reminded me of the plumbus commercial, lol.
Excellent presentation. My knowledge of refining was just tripled in 15 minutes. Also hit topics I had forgotten like organic chemistry. I’d have to watch it again and take notes to pass the quiz, though.
Amazing video with a cool live chat while it premiered! Please schedule it next time so we don’t miss a thing! Now I’m going to watch it again a few times to properly understand everything said. 😅
Ignition!: An Informal History of Liquid Rocket Propellants by John Clarke is a great read for this sort of stuff. Executive summary:If it starts bubbling, run for the hills!
Are you going to do something about the new updated Scot Munley mod ?
What's new about it?
@@markmcculfor6113 science descriptions and works in 1.12.X
"Ignition!: An Informal History of Liquid Rocket Propellants" is a fascinating read on this subject.
In the Ammonia diagram, it showed basically waste steam being bled out of the system, do they use that in conjunction with a turbine to generate electricity that could then be fed back into the system for the preheaters or compressors or would the added pressure cause problems and it is basically just wasted energy?
wasted energy. There wouldn't be a steady reliable stream.
In a modern chemical plant, waste steam is fed into what’s called a “multiple effect” generator, where the low quality steam is used to preheat water or even lower quality steam to use up the temperature differential. So-called “triple effect” steam generation, where this trick is employed throughout the steam plant up to three times, are not uncommon in industry. Ultimately recovering this heat is limited by 1) the phase transition back to liquid and 2) the temperature differential you need to bridge, since more heat will flow if the counter-current streams have a large difference in temperature; at some point the capital and floor space won’t be worth getting that last bit of heat back.
In regards to RP-1, Scott, IIRC the crude oil used to make it is a specific type extracted from just four oil-wells.
The ATF has entered the chat…
Its so cool to have those kind of videos going very deep into what’s actually going on. Really cool to see everything i’ve learned so far in university like proton spin of hydrogen or joule Thompson effect etc sooo fascinating
Cool beans
No Beans.!!😉
great comment
@@carlbrown5150 NOOOOO!
Cool cool cool
Hello Scott, what a great explanation for something we usually take for granted. H2 production is not only a problem for the aerospace industry. Actually, it is a problem much closer to the earth - producing H2 to power hybrid and fuel cell buses for urban transport requires very complicated and expensive infrastructure.
"When a mommy and daddy fuel love each other..."
Excellent presentation, very deep dive to fuel chemistry in an easy way to understand. Very many thanks !+!
Joule-Thomson is long outdated, because it's horrible inefficient.
Turbo-expander to nearly liquefaction and the last few Kelvins by Joule-Thomson, to avoid turboexpander blade erosion damage from high speed droplet impacts is the way they do it nowadays.
Unfortunately not easy to downscale, because turboexpander turbine needs to run at insane rpms due to Reynolds-number scale matching...
Thank you, I knew about Claude process, but hadn’t got the detail about blade erosion.
The Me-163 Komet ran on quite an exotic propellant & oxidizer mix, C-Stoff and T-Stoff. Well worth reading up on it.