Question

Buffer solution problem: Calculate the pH of a solution that is 0.30 M in HF and 0.15 M in NaF?

Answer 1

Writing out the chemical formula would be HF + H20 = H30+ + F- . I would do an ICE table to find out what everything is in equilibrium and thats where I get stuck. I don't have a Ka value. Where do I find it/how to I solve for it?

Answer 2

where is NaF in your chemical formula?? You have it as one of your givens but were would you use it in your solution?

Answer 3

NaF would dissociate in solution with Na becoming spectator ion. So the concentration of NaF is used for the initial concentration of F-

Answer 4

You can look up Kas. There is probably a table in the back of your book. Acid dissociation constants. 7.2 x 10-4. This relationship is called the Henderson Hasselbach equation.
pH = pKa + log [A-]/[HA]. Use molar quantities and plug it in. ICE table will give you the same answer.

Answer 5

Aha! I see! I thought that I was supposed to calculate that somehow, lol. I found it now, thanks!