How much water (ml) is needed to be added to 100ml of 0.53 acetic acid to make a solution's pH=3?

Question

How much water (ml) is needed to be added to 100ml of 0.53 acetic acid to make a solution's pH=3?

Answer 1

first lets find the molarity  of an acetic acid solution that hs that pH=3,...  or [H+] = 1.0e-3 Molar

HC2H3O2 --> H+ & C2H3O2-

K = [ H+] [C2H3O2-] /  [HC2H3O2]

1.8e-5 = [ 1.0e-3] [1.0e-3] /  [HC2H3O2]

[HC2H3O2] = 1e-6 / 1.8e-5 = 0.05555 molar

===================

now the dilution formula:

C1V1 = C2V2

(0.53M) (100ml) = (0.05555M)(V2)

V2 = 954 ml

your answer is: you have to add 854 ml of water