A laboratory technician records the titration curve for the addition of 0.100 M NaOH…
CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A laboratory technician records the titration curve for the addition of 0.100 M NaOH to 25.0 mL of a monoprotic weak acid HA. The pH at the equivalence point is measured to be 8.78.
(a) Write the balanced net-ionic equation that occurs in the solution exactly at the equivalence point.
(b) Identify the conjugate species responsible for the pH being greater than 7 and describe, in words, the chemical process that produces hydroxide ions.
(c) Using your answer to part (b), explain why the pH at a strong-acid/strong-base equivalence point is neutral whereas the pH here is basic.
(d) Predict qualitatively how the equivalence-point pH would change if an acid with a larger Ka were titrated under identical conditions. Justify your prediction without performing a numerical calculation.