#NaA

A weak acid HA ( Ka = 1.6 × 10⁻⁶ ) is mixed with 0.05 M NaA and 0.1 M HCl in equal volumes. What is the pH?

After mixing: [HCl] = 0.05 M , [A-] = 0.025 M , [HA] negligible due to common ion effect. Ka = ([H+][A-]/[HA]) , [H+] ≈ 0.05 , pH = -log(0.05) = 1.3 .

Ref: NCERT Class 11 Chemistry > Chapter 6: Equilibrium > Topic: Buffer Solutions and Solubility Product and Common Ion Effect