Question

what will be the pH change when 0.01 moles of CH3COONa is added in 1 litre 0.02 M CH3COOH solution?

Answer 1

The pH change when 0.01 moles of CH3COONa is added in 1 litre 0.02 M CH3COOH solution is equal to 1.25.

• pKa of acetic acid is equal to 4.8 .
• pH of a weak acid is equal to (pKa-logC)/2
• So, pH of 0.02 M acetic acid comes out to be 3.25.
• When we add sodium acetate to acetic acid the resulting solution is an acidic buffer solution.
• pH of an acidic buffer solution is equal to pKa + log([salt]/[acid]).
• [salt] =[sodium acetate]=0.01 M and [acid] = 0.02 M.
• So, the pH = 4.5.
• Therefore, change in pH=1.25.