A research protocol may expose a buffered solution to sequential additions of both…
CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A research protocol may expose a buffered solution to sequential additions of both acid and base: up to 0.050 mol of H⁺(aq) or 0.030 mol of OH⁻(aq) per liter. Three 1.00 L benzoic acid/benzoate buffers (pKₐ = 4.20) are proposed:
(1) For each proposed buffer, calculate separately (i) the maximum moles of added H⁺ that can be neutralized before the conjugate base is exhausted and (ii) the maximum moles of added OH⁻ that can be neutralized before the conjugate acid is exhausted.
(2) Determine which buffer(s), if any, can withstand both the acid and base challenges specified in the protocol without exhausting either component.
(3) Select the buffer you would recommend for the protocol and justify your choice by considering both capacity and expected pH stability during the successive additions.