Question

if CH3COOH=0.1mole per dm3 and that of CH3COONa=1.0 mol3 per dm3.The pH of buffer is

Answer 1

$CH_3COO$ is a monoacidic weak acid with $Na$as an alkali metal hence $CH_3COONa$

The general expression for The weak acid $Ka$ is ;

$Ka$ $=$ $[H^+_{aq}][A^-_{aq}] \over [HA_{aq}]$ $mol/dm^3$

Which translates to;

$[H^+_{aq}][salt]\over [acid]$ $mol/dm^3$

Hence $[CH_3COO^-_{aq}][Na^+_{aq}]\over [CH_3COONa]$

The pKa value of $CH_3COONa$ $=4.745$

From the formula

$pH=pKa+log$ $[A^-]\over[HA]$

$=4.745+log$ $[1.0]\over [0.1]$

$=4.745+log 10$

$=4.745+1$

$=5.745$

The pH of the buffer is $5.745$

Hence the the buffer is acidic.