Just two more to check, thanks!

Question

1) The pH of a 1.25 M solution of unknown monoprotic acid is 5.43. Determine the value of Ka for this acid. HX <--> H+ + X-. (I obtain 1.0 x 10^-11)

2) Calculate the pH of a solution which is 0.73 M benzoic acid. Ka = 6.5 x 10-5, HC7H5O2 <--> H+ + C7H5O2- (Another icebox problem, I obtain 2.2)

Answer 1

I agree with #2. For #1 I obtained 1.1E-11

Answer 2

I expect the difference in #1 is that I didn't read anything on the calculator but kept everything in until the final answer.