A student is preparing to perform an acid-base titration where sodium hydroxide solution, NaOH(aq)\text{NaOH(aq)}NaOH(aq), is added from a burette to neutralise hydrochloric acid, HCl(aq)\text{HCl(aq)}HCl(aq), in a conical flask. The volume of hydrochloric acid is measured using a volumetric pipette. Upon completing the titration, the student notes that the volume of sodium hydroxide required to reach the end-point is smaller than the expected theoretical value. Which of the following is a possible reason for this?
The conical flask was rinsed with distilled water prior to the titration.
The burette was rinsed only with distilled water prior to being filled with sodium hydroxide.
The volumetric pipette was rinsed only with distilled water prior to being used to measure the hydrochloric acid.
The conical flask was rinsed with hydrochloric acid prior to the titration.
77 exam-style questions on AQA A Level Chemistry Acids and bases (A-level only), covering Brønsted–Lowry acid–base equilibria in aqueous solution (A-level only), Definition and determination of pH (A-level only), The ionic product of water, $K_w$ (A-level only), Weak acids and bases $K_a$ for weak acids (A-level only), pH curves, titrations and indicators (A-level only), and Buffer action (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.