Three phosphate buffer solutions are prepared at 25 °C
CHEMISTRY · Subjective · A Level · Chemistry · Acids and bases · Acids and bases
Problem
Three phosphate buffer solutions are prepared at 25 °C, all using the same weak-acid/conjugate-base pair with pKa = 7.2:
• Buffer A: 0.20 M HA and 0.20 M A⁻
• Buffer B: 0.10 M HA and 0.10 M A⁻
• Buffer C: 0.20 M HA and 0.02 M A⁻
Rank the buffers from most effective to least effective in resisting pH change when (i) a small amount of strong acid is added and (ii) a small amount of strong base is added. Provide a brief justification for each ranking.