7.70     The ionization constant of benzoic acid is 6.46 × 10-5 and Ksp for silver benzoate is 2.5 × 10-13. How many times is silver benzoate more soluble in a buffer of pH 3.19 compared to its solubility in pure water?

Answers (1)
M manish

It is given that, 
pH of buffer solution is 3.19. So, the concentration of H^+ ion can be calculated as; 
[H^+ ] = anti\log(-pH)
             = antilog (-3.19)
             = 6.46\times 10^{-4}M

Ionization of benzoic acid;

C_6H_5COOH\rightleftharpoons C_6H_5COO^-+H_3O^+
It is given that K_a = 6.46\times 10^{-5}
K_a =\frac{[C_H_5COO^-][H_3O^+]}{[C_H_5COOH]}
\frac{[C_H_5COO^-]}{[C_H_5COOH]}=\frac{[H_3O^+]}{K_a} = 10

Let the