Question

1)What is the pH of a 0.25 M solution of acetate (CH3COO-) with a pKa of 4.76?


2)If the [OH] of a solution is 2.95 x 10-5M, what is the pH of the solution?

3)Determine the pH at the equivalence point when 25.00 mL of 0.1056 M CH3COOH is titrated with 0.1056 M NaOH.



4)Determine the pH of a solution after 20.00 mL of 0.4963 M HI has been titrated with 12.64 mL of 0.5174 M NaOH.

Answer 1

Btw for number 4 i got ph of 1, not sure if its right..

Answer 2

In a hurried calculation I got 0.9841 for pH and I carried it out to 4 significant figures and used all of the digits in the numbers themselves.

Answer 3

1. acetate = Ac
......Ac + HOH ==> HAc + OH^-
I....0.25..........0......0
C.....-x...........x......x
E...0.25-x.........x......x

Kb for Ac = (Kw/Ka for HAc) = (x)(x)/(0.25-x)
Solve for x = (OH^-) and covert to pH. The answer is around 8+.