How to calculate the pKa

[Daniel Hernandez 1G]

Will we be given the pKa value of a solution or will we be required to calculate it? If we are required to calculate it, how do we go about doing so?

[Chem_Mod]

pKa is defined as -log (Ka) where Ka = [H+][A-]/[HA].

[Brandon Le 3C]

I think whether or not the Ka value is given depends on the question. But like the previous user said, Ka = [H+][A-]/[HA]. However, it's possible that we would be given multi-step reactions (two subsequent reactions), in which case there would be two Ka values (Ka1 and Ka2) and we would need the whole Ka value. The overall Ka value would be Koverall = Ka1 * Ka2.

[Keon Amirazodi 3H]

p in chemistry means -log. So pKa values would be calculated by finding the -log(Ka). Similar to how pH is calculated by finding the -log[H3O+].

[Lesly Lopez 3A]

Hi,

pKa can be solved with -log (Ka).
I actually had a question. pKa, is it dependent on something or is it something separate?

[Ruth Rosales 3D]

pKA = -log (Ka)

If you are missing other values, this is how to find them:

Ka = [H+][A-]/[HA]

1.0 * 10^-14 = [OH+][OH-]
14.00 = pH + pO
pH = -log [H+]
pOH = -log [OH-]

[305405193]

I utilized this video to help me gain a better understanding. https://www.youtube.com/watch?v=IQ6gHQAg_Nk

[705383815]

As long as you understand the fundamental properties of logarithms, you're fine. You just need to apply them!

[Joseph_Armani_3K]

pKa is defined as -log(Ka), Ka being the acidity constant, and "log" being log base 10.

If you were given pKa you would probably have to find Ka, in that case, it would be 10^(-pKa). Hope this helps!

[Sahaj Patel Lec3DisK]

If you were given the pKA, you would find the anti log of that to find the KA. The anti log would be 10^pKA. Hope this helps!

[Nicolette Simoni 3L]

pKa is = to -logKa (this applied to the same to pKb = logKb). Keep in mind that if your Ka value is small, the pKa value will be greater.

[Aarushi Verma 2I]

To find pKa, you would need to have the Ka value, which you can get by setting up the equilibrium equation with products at the tops and reactants at the bottom. Once you have Ka, just take the -log(Ka) which will give you the pKa value.

[Maya Johnson 2a]

If you are given pKa, use -log(Ka) to solve, and Ka= [H+][A-]/[HA]. I believe that the whether or not you are given pKa just depends on the question.

[Alejandro Gonzalez 2G]

If you are given the Ka value, you can just use the -log(Ka) in order to find the pKa value.

[Kushaal Madadi 2F]

It depends on the question and what you are given. Often times, you will have to calculate it.