A laboratory buffer solution is prepared by dissolving equimolar amounts of acetic…
CHEMISTRY · Multi-part · AP · Chemistry · Acids and Bases · Acids and Bases
Problem
A laboratory buffer solution is prepared by dissolving equimolar amounts of acetic acid and sodium acetate in water. A student then adds a very small volume of concentrated hydrochloric acid to the mixture while keeping the total volume essentially unchanged.
(a) Identify which chemical species in the buffer mixture will react first with the added hydrochloric acid. Justify your answer based on chemical reactivity.
(b) Describe qualitatively how the pH of the solution is expected to change after the addition. In your explanation, articulate why the observed pH shift is smaller than would be observed if the same amount of acid were added to pure water.
(c) Predict whether the numerical ratio [acetate]/[aceticacid] becomes larger, smaller, or remains unchanged after the addition, and explain the reasoning behind your prediction.