[jmg12]

1. A 0.10 M solution of the weak acid HA has a pH of 2.96. What is the percent dissociation of HA in this solution? What is Ka for HA?

2. An unknown acid is dissolved in water. The solution is divided into two equal parts and one part is titrated to a phenolphthalein end point with NaOH solution. The two solutions are then mixed and the resulting pH is found to be 3.25. What is the Ka of the unknown acid?

I really don't know how to go about any of these problems.

[Honclbrif]

What is the definition of pH?

What does it mean if the pH is 2.96 but the total concentration of the acid is 0.10 M?

[jmg12]

a pH of 2.96 means the H3O+ conc. is 0.0011. That's obvious. But where do I go from there?

[Honclbrif]

If [H₃O⁺] = 0.0011 M, what is the concentration of A^-? What's the concentration of HA?