Find the Ka using Equivalence Point
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- เผยแพร่เมื่อ 25 เม.ย. 2013
- You can use the pH at equivalence to figure out the Ka of the acid that was titrated.
Be careful ... rounding errors can be costly here so don't round until the very end.
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Damn, I had a similar problem to the one in this video with the same reaction, but the pH is unknown while the "Ka" isn't, on mine.
can I start doing it with Na+ instead of CN-? would it make any difference if I am doing so? also the number of steps would drastically decrease so why didn't you just started with it?
Dang, that was one of the more harder acid-base problems I've seen.
why did you use kb instead of ka when finding the value of x?
So clear, thanks!
Why not do a diprotic acid like sulfurous with naOH
Yeah man it stumped me too when I first saw it. I'm like ... what?
my only problem is writing the equations. the equations ruin everything for me.
Why did you have to find the Kb before finding the Ka?
this was so helpful
My hero!
Thank you so much!
Wait a minute. How does HCN completely dissociate? Is it not w weak acid? I dont understand how you get the 1:1 ratio.
+Monkey D. Luffy As long as one of the reactants is strong the reaction will go to completion. In this case NaOH is a strong base so the reaction will go to completion even though HCN is a weak base. You almost had me trippin burh.
Thank you!
Saved my ass again. Thanks!
how did you get the 1.2691 at OH
Where did you get the 14 from?
I'm confused on why you added two volumes together when you were only provided with an intitial .20 mL...where is the other .2 mL coming from?
This may seem like a very confusing concept, however for titration related problems, you must consider the "total" volume/amount used. 20 mL of NaOH (Base) was added to 20 mL of HCN (Acid) to titrate the acid, so the total amount is 40 mL.
I think of it more like a "dilution" concept. When you titrate the base, you're not just adding the base, you're also adding water. The new volume of the water would be the volume of the water in the acid and the volume of the water from the base you just added. Therefore, the volumes are additive.
u calculate in the calculator 10 to the power of what?
But... you were going to find Ka for HCN not CN-
CN- is to Kb, HCN is to Ka