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Which compound can be purified by forming a hot aqueous solution that recrystallises on cooling? A - AQA - A-Level Chemistry - Question 34 - 2019 - Paper 3
Question 34
Which compound can be purified by forming a hot aqueous solution that recrystallises on cooling? A. Cyclohexene B. Ethanoic acid C. Phenylamine D. Benzoic acid
Worked Solution & Example Answer:Which compound can be purified by forming a hot aqueous solution that recrystallises on cooling? A - AQA - A-Level Chemistry - Question 34 - 2019 - Paper 3
Step 1
Identify the compound
Answer
To determine which compound can be purified by recrystallization, we need to consider the solubility properties of the compounds listed at elevated temperatures and how they behave when cooled.
- Cyclohexene: This is a non-polar compound and would not dissolve well in an aqueous solution.
- Ethanoic acid: Soluble in water, but typically does not form crystals effectively in aqueous solution as it remains dissolved.
- Phenylamine: This compound is also non-polar in nature and has limited solubility in aqueous solutions for the recrystallization process.
- Benzoic acid: This compound is known to dissolve well in hot water and can form crystals as the solution cools.
From this analysis, the compound that can be purified through this method is Benzoic acid.