Final answer:
In an acid-base titration, a burette is used to deliver measured volumes of a known concentration titrant to determine the concentration of an unknown solution. A pipette is used to accurately measure a fixed volume of liquid, making it suitable for measuring the sodium hydroxide solution.
Step-by-step explanation:
In an acid-base titration, a burette is used to measure the citric acid solution because it allows for accurate and precise delivery of variable volumes of liquid. The burette is designed to deliver measured volumes of an acid or base solution of known concentration (the titrant) to a flask or beaker that contains a solution of a base or acid, respectively, of unknown concentration (the unknown). By carefully measuring the amount of titrant solution added to the unknown, the concentration of the unknown can be determined.
On the other hand, a pipette is used to measure the sodium hydroxide solution because it is designed to accurately deliver a single volume of liquid. A pipette is often used when a fixed volume of liquid needs to be transferred, such as when preparing standard solutions. It allows for precise and reproducible measurement of a specific volume of solution, making it suitable for measuring the sodium hydroxide solution in this context.