A student is required to dry a liquid sample of pentanoic acid - AQA - A-Level Chemistry - Question 25 - 2019 - Paper 3

To determine the suitable drying agent for pentanoic acid, we need to consider the properties of each option:

1. Calcium oxide (CaO): A strong drying agent that can remove water effectively but it may react with acidic compounds, potentially leading to unwanted reactions.

2. Calcium sulfate (CaSO₄): A neutral substance that is often used as a drying agent. It does not react with pentanoic acid and is suitable for this purpose.

3. Potassium hydroxide (KOH): A strong base that can react with acids, which makes it unsuitable for drying pentanoic acid as it could neutralize the acid.

4. Potassium carbonate (K₂CO₃): Although it is milder than KOH, it may still react with acids and is less commonly used as a drying agent compared to calcium sulfate.

Considering these factors, the most suitable drying agent for drying pentanoic acid is Calcium sulfate (B).