Benzene - Periodic Table of Videos
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- เผยแพร่เมื่อ 14 ต.ค. 2024
- We take a look at benzene by freezing it and burning it.
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Intrestingly in german petrol is called "Benzin" which sounds pretty much like "Benzene" which I know as "Benzol" (wikipedia sais "Benzen" is a synonym to that in german)
languages....
i mainly clicked on this cause of the weird fingernail on the cover
actually, the name aromatic was given to this class of compounds because of toluene (which was discovered earlier than benzene), a chemical which was found in an exotic, nice smelling plant which was thought to smell like that because of the newely found toluene
As I was a teenager I bought Benzene (Benzol) in our local drugstore. I handled it respectful but without special precautions.
I clearly remember the sweetly smell.
It's about 30 years ago.
After about a whole year, i came back to this video. I started my A-levels this year and I am just studying reactions of aromatic compound . It feels so great to know more about this compound and came back to this video!
When I took organic chemistry as an undergraduate in 1970 we used benzene by the GALLON for everything! It's an excellent solvent. We practically drank the stuff. And when we were finished with it, we simply dumped it down the drain.
A hexagon with a ring inside it... that's nuts.
question: could you not put the alcohol in the freezer and then filter that to take out the Benzene (am just a simple soul so forgive me if it is a really dumb question)?
I did this last year, the Kekulé structure and all. I found it very interesting with the delocalised pi-electron system.
I'm learning about aromaticity now in my chem class and they are amazing compounds! Really cool to learn about!
4:24 "0 ml Nitric Acid"?
this channels caused me to LOVE science classes
I tasted a bit of ethanol from a lab recently. Shit. ;__;
Eh? Does the professor collect plastic bottles :D?
We Call petrol benzine in dutch
You guys should do a video on toluene.
@cath1594 Alcohol and water form an azeotrope (a mixture with a lower boiling point that either pure substance).
Pure ethanol boils at 78.3 C, and pure water boils at 100C. The catch is that a mixture of 96% ethanol/4% water boils at 78.1 C.
When you distil a mixture of ethanol and water (as long as you start from more than 4% water) - the first thing that distills is the 96/4% mixture, and this continues until all the ethanol has distilled. Then only the water is left.
Excellently formatted video, I learned lots. The repetition of stuff later on that we had covered before (Such as mentioning that it is aromatic at the start, then explaining that later) really helped all of it to sink in!
Thanks :)
Great video, I always wondered why they called gas stations "benzinkút" in Hungarian, the literal translation being benzene pump. This video solved that mystery.
I love these videos. Great job professors and/or chemists!
very good information on the benzene presence in lab alcohols. I'll keep that in mind for the future. Thanks you for everything periodicvideos
MTBE is used instead of benzene in lead-free gasoline nowadays
... LEO says GER... That is Loss of Electron, Oxydation. Gain of Electron, reduction. It is the ability to lose this electron that makes oxygen so "special"
the double bonds in benzene are conjugated throughout the molecule, so yes, you are right about the continuous pi bond (as was mentioned in the video, the electrons are delocalized). the resonance structures of the kekule model are mostly used to keep track of electrons and don't actually exist in reality
He says that benzene is very restricted and controlled, but in my AP Chem class we used it in several labs during our organic chemistry unit. Not sure if this is typical or not. Keep up the good work!
so if i were to place a bottle of petrol in the fridge, i could extract the benzene from it?
@cath1594
You can get rid of the excess water after distillation by drying with an anhydrous salt such as CaCl2 or MgSO4.
I am no expert a chemistry, but double bonds and continuous pi-bonds are two separate phenomena, no? I recall a paper I read regarding the bond lengths of single and double bonds of C were 135pm and 147pm, respectively. The bond lengths in Benzene are 140pm, disproving the hypothesis of alternating single/double bonds and showing that it is instead a continuous pi-bond.
@Fenikxpikx
As a rule of thumb. Organic compounds found in a lab are usually colorless, white, or slightly yellow
One of your best videos. Great explanations, and the experiment worked.
@Perscriptions In Spanish the word for petrol is 'bencina' (pronounced: benz-EE-nuh), and yes, there is benzene in petrol.
@ClercLe Try accelerating up a steep hill in high gear, and listen for a tinkling sound. Knocking, pre-ignition is sometimes called 'pinking' and this is perhaps a better description. Essentially it's an explosion in the cylinder rather than a burn. Diesels would always pink if they used a carburator, because all the mixture would ignite at the same time, but they don't, they're fuel injected, and burn progressively as the fuel is injected.
That was a great video, I enjoyed it very much - I've learned a bit about aromatic compounds in organic chemistry at college and benzene somehow always managed to get my attention in a special way. Maybe because my teacher told us to think of its electronic cloud as a donut because of the electron delocalization. I also didn't know why these coumpounds were called "aromatic", but now I do. :D I'm looking forward to see more videos! Greetings from a bioengineering student from Portugal :)
How many squeaky toys does the prof even have?
YAY! Now I know what TNT stands for! :D Thank you guys! I love you all!
@lejink one simple way is to burn it - benzene will burn with a yellow, sooty flame due to higher carbon to hydrogen ratio (incomplete combustion), whereas alkanes (non-aromatic compounds) burn with a clearer flame (more complete combustion to water and CO2).
@lejink That's actually a very good question. I think they both have it wrong that the C6H6 structure was known. Combustion analysis developed in the 1820's would have shown that the structure is of the empirical form (CH)n, but I don't know how they could have found out the molecular formula in the mid 1800's. As I understand, Kekule only used the information of the empirical formula and the amount of isomers of various benzene derivatives to determine the stucture of the molecule.
@zbret The reaction is correct, although it could be an instable reaction, soft drinks have Sodium or Potassium benzoate in it, wich produces benzene and you ingest it, the reaction is not always certain, as you said it need unknow time and heat but it exists, but we should concern ourselfs more of what comes from Air pollution or products we use in the daily basis such as detergents,perfumes etc.
I visited the Kekulé memorial in Bonn this year when I went to my partner's school reunion there and visited the laboratory of Justus von Liebig in Giessen - when the professor goes to Darmstadt next time - perhaps he should take a trip to Liebig's laboratory as he was one of the first to develop lab based teaching.
I guess things might be a bit different in different places & diff'nt times. When I was studying chemistry there weren't any fume hoods filters in neither the "technicall college" (as it was called in Poland back then, 30 yrs back) nor in the university. But regulations might have changed a bit since then, I agree. Still, most of the fumes in majority of labs isn't really dangerous and the amount of them is rather limited, so I don't see much need to use any filters (but they might to nowadays)
Is there a video where it is explained how chemists do to find out how atoms in molecules are arranged and why it is important to know?
i love periodicvdeos it reminds me of my university days
had to go to the fifth page to find it, but its here. Thank you.
In both this benzene video and the lead video, you brought up engine knock (or ping) but avoided telling us anything about the chemistry of that process, and how it is altered by either benzene or tetra ethyl lead. Just saying the car has trouble going up hill is not much of a chemistry lesson.
I am disappointed that you didn't take this opportunity to inform us more specifically.
I love your videos so much! I'm going to study chemistry :)
Faraday's Benzene = Heisenberg's Meth of the chemistry world.
@techguy33 Because it has a high freezing point, you can have benzene in another solvent, and precipitate it out after hot filtration. As it cools, crystals form, and then you can just get rid of the solvent and voila! nice pure benzene
In my highschool chemistry class we just learned that benzene does not in fact contain any double bonds, but that each bond is an intermediate between double and single. Now I don't know what to believe.
In Sweden we call petrol, or gasoline, "bensin" which is pronounced pretty much the same as benzene. A fair guess would be that the name comes form the benzene present in the petrol, though led based petrol ALSO was called "bensin".
Was benzene present in led based petrol as well? If not, why do you think the swedish word for led based petrol was "bensin"?
How did they figure out the structure of molecules way way back in the day? Just by the charges and stuff?
@ChumpusRex and @98JMA thank you both!!!!
8:42 good note, too many people forget about it...
yes, but then it's not a kekule structure anymore. kekule models don't actually exist per se, but they're useful for keeping track of electrons when considering how benzene reacts with other substances. not really sure if i answered your question though..
Could someone please explain something a little bit unrelated that the comment about burning made me think of?
What exactly IS burning?
I'm only fifteen years old, by the way, so I do apologize for my incompetence on this.
It seems that some of the really simple questions like that I've just never thought to ask.
When something burns, is it turning into a different chemical, or just releasing energy and breaking up in the air? What happens to substances burning, and why is oxygen necessary?
The Kekulé model is demonstrated with alternate double bonds on each carbon atom in the ring (a total of 6 sigma bonds and 3 pi bonds). This, however, is incorrect in reality.
The delocalised model is represented by a simple ring inside of the hexagonal carbon structure, which represents the overlapping 2p orbitals which form the shared pi bond. All evidence thus far (e.g. unreactivity of benzene, equal bond lengths) has demonstrated this to be the correct model. :)
@lejink First they would have burned some benzene in excess oxygen and measured the ratio of CO2 to water vapor given off. That told them Benzene was made of equal parts H and C. After that, they could determine the number of molecules there are in a gram of C6H6 by applying the ideal gas law to some benzene vapor. Then they figure out how many CH groups it takes to equal that molecular mass.
Why was the label on the bottle covered up with black marker? There is only one structural form of pure benzene, and it was already drawn for us, so it's not like they censored the structure.
Ah yes, benzene, the one chemical I am unable to get my hands on for making true military grade napalm.
Yes and not. Benzene is added to petrol in small quantity as an additive
@johnmacward haha...we're both old and boring now, just hoping our offspring inherit their dads good fortune and their mothers brains
I'm interesting in knowing how Faraday made his benzene and what process may have created the trace impurities. Is there any explanation for this? Thanks.
'wot we have here is smice' - why are you using mice? Oh! you mean 'some ice' lol
I had always wondered exactly why reagent grade ethanol is labeled unfit for consumption (besides the fact that drunk chemists and laboratories don't mix, of course).
Thumbs up!
The mystery behind the hotness of Boron Girl will confuzzle me for the rest of my days (or possibly for the next 5 minutes or so). I can't explain it, and I can't deny it. *UGGGGH*
@lejink I think it has something to do with the various bonds it has, such as what it bonds with and how difficult it is to get it to bond.
so is the difference between benzene and cyclohexane the double bonds?
Nitrobenzene smells like almonds? Odd, so does benzaldehyde.
OMG i wish i had 1 copy of the professor's lab book hahah :) It's soooo awesome ^^
Is it just me or is this professor kind of like the Walter Lewin of chemistry?
And it turns back into benzene in contact with ascorbic acid!
Otherwise known as vitamin C
But in that case isn't the kekule model modified with either an internal dashed hexagon, or a solid circle?
Is there theoretical evidence for all the lengths of the C-C bonds being equal, without measuring them by X-Rays or scanning tunneling microscopes? Or is the distinctive structure with its delocalisation of electrons only proved by those techniques?
Benzene was (and i think sometimes still is) used by swiss watch manufacturers for washing their hands.
it is any posible way to make benzine (to form ring, not from ring having compunds)? i found out it is posible using acetilene, and lignin from wood (has rings!) so it is posible? and how?
I have a question, according to a link from TH-cam, there is a concern about soft drinks having benzene due to the reaction of x Bensoate (Na or K), and Citric Acid, which when both chemicals are in a soda (and they are!), and are exposed to heat or time, they convert to Benzene. The link sent you to a news article stating 2-4x the benzene levels considered safe for water are found in sodas. Is this reaction correct? What would cause it (ie how much time or heat?), etc?
There's a whole bunch of other stuff we wouldn't have without benzene as well.
German = "Benzin".
Sounds almost exactly the same as engl. "Benzene".
Can we get a whole video about the professor's water bottle collection?
this is good for my work on this great vid
@RitchieFelix for plasma this might work (but it will be verey dificult for some elements) but superfuildity is something rather complicated and I am not sure if there are too much chemicals that can be made superfuid... the only one I know of is Helium...
Double Bond, SIngle Bond , Double Bond, SIngle Bond
Say that really fast when your tipsy lol
Thanks for all the great vids btw learned so much watching them :)
Very nice video!
@Trekkie0401 The empirical formula is just (CH)n. In the video they twice make the claim that the molecular formula was known, although it wasn't.
@eveningniteshade for me it was quite like "so what we have here is just nice"
Of course, but it still has an aromatic ring.
Not all aromatic compounds though, phenol smells like old paint. A lot of the aromatic things I've been working with recently just smell bad.
When my brother was about 6 or 7, he thought he would be a smart and take a swig of dad's beer that he had setting while he was working on his truck.
Unfortunately, the can had gas in it, not beer (I guess he was working on the carb?)
That was a pleasant experience. Almost as pleasant as the huge dose of chlorine gas i hit him with (accidentally) while playing with an old school freon leak detector, or watching him pass out after hitting two balloons worth of helium off my uncle's tig welder.
Benzene at nne time was used to wash you're hands in the lab
Can you ignite solid benzene or does it not sublime in sufficient enough quantities?
@ClercLe It shouldn't be a problem unless you are leaving you are allowing the petrol tank to vent...
I can't believe that the lady in the video was working with benzene with the hood that open.
I thought benzene was banned in UK universites. In our lab in Singapore we have about 8L of the stuff that no one uses. My boss doesn't want to get rid of it because its so expensive to dispose of.
Have you mentioned the distinctions between Alkanes, Alkenes and Alkynes?
While she is pipetting out the benzene, she should have placed the blue bottle cap upside-down so as not to contaminate it.
@glenwoofit actualy aviation fuel is still leaded so no knead to worry about benzene (don't know weather or not that helps things)
7:00 Professors tips for health and safety when coping with the modern economy.
Frankly, I'd be more worried about accidentally drinking the gasoline or nearly 100% alcohol than just a trace of benzene.
Or Dynamite. Or Hydrocholric Acid. Or Boron Tribromite, or tetrasilacyclobutadiene, or ferrocene, wait, what are we talking about again?
Also should the bottle be 'reused' with a hand-written label? I suspect this is a rather low grade of benzene that many labs keep around for miscellaneous uses, so a little contamination is not a problem.
quick question.. do most molecules have a solid liquid and a gaseous state?