Question

What is the pH solution containing 0.30 M HCOOH and 0.52 M HCOOK?Compare your result with the pH of a 0.30 M HCOOH solution

Answer 1

HCOOH(aq) + H2O(l) = H3O+(aq) + HCOO-(aq)

pKa = 3.77

$pH = pKa + log ( \frac{[HCOO^-]}{[HCOOH]} )$

$pH = 3.77 + log ( \frac{[0.52]}{[0.30]} )$

pH = 4.01

$Ka=\frac{[HCOO^-][H^+]}{[HCOOH]}=\frac{x^2}{0.3}$

$pKa=logx^2-log0.3$

$logx^2=0.52+3.77=4.26$

logx=pH=4.26/2=2.13