Standardization of NaOH using KHP experiment
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- เผยแพร่เมื่อ 9 พ.ย. 2015
- A titrationof KHP (potassium hydrogen phthalate) is run using 0.919 g of KHP and is titrated with a solution of NaOH that is approximately 0.2 M in the presence of phenolphthalein. The volume of base used to reach the endpoint is used to calculate the concentration of the NaOH.
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A. I don't think he really cares that his KHP measurement was off. B. I think it's important that we address the fact on how cool that whiteboard/projector set up is.
I know I'm a little late, but I was thinking the same thing about the whiteboard.
Used this video to help me study for my inorganic lab final. Very helpful, thank you!
Extremely useful for helping me complete my titration lab in chemistry! Thank you x3000
Thank you very much! I listened to this today because I wasn't sure how doing a titration helped arrive at molarity and this helped a lot! I suspect the lab handout didn't elaborate much because the teacher is planning to talk about the specifics in class, but since the lab is the day after tomorrow I'd rather know now.
That was a lot of help! Thanks!
Thank you sir, this was really helpful as all of your videos!
Thanks. You're a legend 🙌
How did you get 0.919 grams of KHP? Aren't you supposed to subtract the tare of the tray? Your sample + tray was 0.903 and the tray alone was 0.016. 0.903 - 0.016 = 0.887 grams.
It read -0.016 after I was done. The calibration gets messed up a bit when they haven't been on very long.
you are a great teacher thank you very much
Very helpful i wish we had more people like you 😁😁
we will be using this video as a reference for our online lab class
can I ask the volume of each lab apparatus used ?
like the burette ?
For the first time when you're adding the khp on to the analytical balance aren't we not allowed to do that? like don't we add the mass first (when it is off the balance)?
Why The KHP used to standardize the NaOH was not pure, but contained approximately 10% by mass of the inert ionic compound potassium chloride
Wanna ask. Why certain method need to heat the KHP before standardise? For example standardise EKOH?
Hello, can I ask if is it okay not to standardize NaOH aqueous solution when you only use it for adjusting pH of your solution and can you please share me anbarticle about it? I will gladly accept your replies.
Thank you!
how do you judge the mass you used?
how do we consider the number of scoops of khp?
so i take it you're using old NaOH then? wouldnt the sodium bicarbonate present affect the titration since it is a weak base? I was going to do a titration and i wasnt sure if i should use my old solution or make some more
He is determining the "effective" molarity of the base, taking all impurities into account.
In my experiment, it was very similar to yours but we were given the option of using a .01% phenolphthalein and a .1% phenolphthalein. Would the titration that had the .1% concentration of phenolphthalein be a darker pink color than the .01%?
Not if you stop at the first light pink color...but yes, if you add additional base at the end.
Thank you, sir
very nice sir
What equipment would allow a fourth significant figure? Just a more accurate measurement for the mass of KHP right?
There are scales that go out to four significant figures... They're expensive. About $3500 last time I checked.
Question: Why did you add the mass instead of subtract the mass measured after transferring the KHP? Shouldn't that mass indicates than mass that is not transferred?
+Ms3k0 It's reading as a negative mass for the final measurement, it's -0.18 g not +0.18g.
you didnt show the eaxct measurement of naoh u used , how much distilate water was aded and other measurments that helps with the experiment
So good
does the amount of anhydrous NaOH in grams dissolved in different volumes of distilled water has something to do with the Normality of NaOH solution? mine reaches 1.63N of NaOH instead of 0.04N. having some hard time here..
What do you mean? The normality is going to be different if you prepare different dilutions.
Please answer. Why do we keep adding small increments of naoh? Is it to allow theNaOH to have more time to react with the remaining KHO? Or to avoid overshooting the endpoint? Anyways thanks, it helped me alot.❤️
Ik it's too late but it's the second part to avoid over titrating
why do we need to degas the water before titration? will it make the molarity of naoh falsly high or falsly low? thanks
I believe CO2 can enter the solution and react with the NaOH to make NaHCO3 and Na2CO3. The solid NaOH used to make the solution can also absorb water and CO2 before you make the solution. But the KHP is very pure so you can rely on the moles of base from the titration.
Thank you sir
How did .919g KPH end up in the flask if you only weighed out .903g?
molarity is number of moles divided by volume of the *solution*
so when i measure the molarity
do i have to take the volume reading after adding the solute
or it well be okay to use the solvent volume only ?
For a dilute solution you would probably be ok to use the volume of the solvent. But it is best to use a volumetric flask and dissolve the solid in a portion of the solvent then fill to the mark to make sure that the volume of the solution is correct.
DebChem
Thanks a lot
how did he get .00450 mols from .919g of khp i get .01293 mols someone help please
Great
What happens if your KHP is wet in titration
When potassium hydrogen pathalte is unavailable then which solution has used to standardisation of sodium hydroxide?
Arunaar then you can used 0.1 normal HCl..
great
How did you figure out the moles of KHP?
I divided by the 0.919 grams of KHP by its molar mass (204.22 g/mol) which is on the container.
is it good for plants?
What is application in real life?
I want to do titration for 0.1 M NaOH solution.How much amount of KHP will I need?
You can use the same amount, If you do you will find that your final volume of NaOH added will be about twice as much.
If you change the amount of KHP you need to work out how many moles(n) you have for the calculation (ie you wont be using 0.00450). So you use C= n/V where C is concentration N is number of moles and V is volume tritrated (in litres).
i want to calculate the pH at end point. so what is the total volume in this experiment ?
Is the mass of KHP not 0.903 - 0.016 g? Why did he add them instead of taking the difference??
How did you get V1 = 0.60ml???
Hi there, I know I'm late, but V1 is the initial reading volume of burette before titration. Some people use 0.00 mL as V1.
But, at the end, how much volume NaOH titrated into flask is what matters most. Not the initial reading
V used = 23.15 mL - 0.6 mL = 22.55 mL
V used = 22.55 - 0 mL = 22.55 mL
Volume titration = Volume final reading - volume initial reading
😊
What is standardisation and why we have to carry it out?
it's determining the concentration to a high precision and NaOH is notorious for absorbing things from the air as a solid which affects the concentration. KHP is very good at being synthesized to very high purity and therefore can be used to determine an accurate concentration. In other words, if you mixed 10.00 g of NaOH with water to form 1.000 L of solution, your concentration would not necessarily be 0.2500 M and the KHP allows you to figure it out.
Scott Milam thank you very much :)
What happends when during the preparation of the KHP solution, some KHP is spilled on the counter. How will this affect the calculated concentration of NaOH?
If your KHP solution contains less KHP than what you intended, the end point of the titration would be reached faster, and the concentration of NaOH would be overestimated
what error in this experiment?
What kind of BOARD IS THAT???? WOW
What is considered as the titrant here? It is supposed to be the chemical with known concentration, and is typically put in a buret. In this case, the NaOH is in the buret but its the one with unknown concentration. Enlighten me pls.
KHP with a known mass is the tritant
Thank you.
What is its use?
What is kip for?
How do you know which indicator to use?
KHP is a weak acid and NaOH a strong base, so the pH at equivalence is above 7, phenolphthalein turns from colorless to pink around a pH of 9. The rationale beyond that you can find here th-cam.com/video/tRsju52Hcn4/w-d-xo.html
Thank you. The pH range of phenolphthalein is about 8 to 10 and I was confused about why it's okay to assume the eq point is right when the color changes if the corresponding pH could be anywhere from 8 to 10, but the real eq point corresponds to only one specific pH. I think this is because the corresponding volume is relatively the same during the steep climb in pH during the eq point. Therefore, if the real eq point is when the pH is 8, the corresponding volume of NaOH used to calculate molarity would be similar to the corresponding volume if the equivlance point is when the pH is 10.
TheTheaterThug The pH +/- 1 derives from the Henderson Hasselbach equation, for an indicator it has a 10:1 ratio when it was 1 pH unit away from its pKa there is a 10:1 ratio of the two colors. So at pH of 8, you have 10 colorless molecules for every 1 pink, and at pH of 10 you have 10 pink for every one colorless. But the amount of base needed to go from 8-10 is less than a drop so any pink color is more than sufficient to identify the equivalence point.
please reply to me. how do you calculate the weight of khp needed for NaOH standarization? let's say I want to standarize 1 N NaOH, how many grams of khp I need?
You would be unlikely to do that, the NaOH is unreliable in concentration, and titrating with KHP doesn't serve any purpose other than education and there are better alternatives to use. But if you did the calculation you would do the same thing as in the video, but you would fine the moles of NaOH from the concentration and volume, the moles of KHP needed would be the same to get to the equivalence point and the mass can be determined by multiplying by the molar mass of KHP.
What are the other alternatives to using KHP?
Google says oxalic acid works, but I'd use KHP since it's monoprotic. KHP works well because it's highly pure.
KHP is a primary standard.
How did you found the moles of NaOH
KHP is a monoprotic acid, so the moles of KHP = the moles of NaOH, it's worked out in steps near the end of the video
Scott Milam thanks
I hope I can also do x16 in real life, for sanity purposes.
Sir I have one doubt why we have to use potassium hydrogen pthalate only for the calculation of molarity and oxalic acid for the calculation normality what is the reason behind that please reply me sir I am waiting for your answer
Hello scott, please I need to standardize Potassium Hydroxide solution( Alcoholic ) of 0.1mol/L. Having dissolve 3g of KOH in 500mL of propan 2-ol.
Please i need your guide on how to use KHP to standardize it. Ensure the concentration. Thanks
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So it’s alright to have the solution with unknown concentration in the burette, i said this to the my professor and he disagreed.
This is true for standardization when you use a primary standard (most likely a solid) to determine the concentration of the solution before you use it in the analysis of anything else.
khp
it makes no difference how much disstiled water you add to KHP?
The H2O doesn't react with the indicator or the KHP and NaOH, so no the amount of H2O makes little difference in this sense. The water just acts as a way for the ions in the KHP and NaOH to react freely with one another. **However adding a large amount or too little of water to the KHP will make a dilute/overly concentrated solution and the ions will be spread farther apart or too crowded together.
@@dad_patrol tnx alot
you didnt even take into consideration the amount of water you dissolved the khp into?
The amount of water doesn't matter at that point. The KHP also does not need to fully dissolve in the water because it will become more soluble as it reacts with the hydroxide.
do not send this to me again or i will stop my donation!!!