Question

Calculate the pH of a buffer solution obtained by mixing 1.5 mole of sodium acetate and 0.09 mole of CH₃​​​​​COOH.

{K_a = 1.8 × 10^-5 }.

Answer 1

From Henderson equation of acidic buffer solution we know, 

pH = pKa +log [A^-]/[salt]

degree of ionization (∞) = √Kc/C = 3.4e-3

 So,[CH₃COO^-] = C∞  = 3.4e-3 × 0.09 = 0.306e-3

 So, pH = 4.7 + log [ 0.306e-3]/1.5 = 4.7 + log 0.0204   (log 0.0204  = -1.69)

= 4.7 - 1.69 

= 3.01