A laboratory keeps 250 mL of an aqueous buffer that is 0.40 M in HCOOH and 0.40 M in…
CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A laboratory keeps 250 mL of an aqueous buffer that is 0.40 M in HCOOH and 0.40 M in HCOO⁻(aq) (pKₐ = 3.75).
The buffer is accidentally exposed to a spill of 0.060 mol of concentrated HCl(aq). No volume change results from the spill, and temperature is held constant.
(1) Calculate the pH of the buffer before the acid spill.
(2) Show, using stoichiometric and equilibrium calculations, whether the buffer remains effective after the 0.060 mol of HCl is added. Report the final pH or explain why the pH cannot be calculated using buffer equations.
(3) A second buffer of the same conjugate pair but only 0.20 M in each component (also 250 mL) is subjected to the same acid spill. Repeat the analysis for this buffer and compare its performance to the original buffer. Provide a reasoned argument that accounts for any difference observed.