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, we need to consider the properties of the agents listed.

1. Calcium oxide (CaO): This is a strong drying agent and can effectively remove water from compounds, but it can also react with acidic compounds, potentially altering the pentanoic acid sample.

2. Calcium sulfate (CaSO₄): This is a suitable drying agent that does not react with most organic compounds, including pentanoic acid, making it the ideal choice for drying the acid without affecting its properties.

3. Potassium hydroxide (KOH): This is a strong base that can react vigorously with acids. Thus, it is not suitable for drying pentanoic acid as it would lead to unwanted reactions and potentially alter the sample.

4. Potassium carbonate (K₂CO₃): This is a milder drying agent, but it is less effective than calcium sulfate in this context.

Based on this evaluation, the most suitable drying agent for the liquid sample of pentanoic acid is Calcium sulfate (option B).