Question

An acetate buffer was prepared by mixing 10 mL of 0.1 M acetic acid and 100mL of 0.1 M sodium acetate. What is the pH of the buffer solution?

Answer 1

Millimoles of CH3COOH=0.1×10=1.0

Millimoles of CH3COONa=0.1×100=10

From, Henderson Hasselbalch equation,

pH=ppKa log $\frac{conjugate base}{acid}$

= 4.24 + log $\frac{20}{1}$

4.24 + 1.3

= 4.54