Question detail
When testing for aldehydes, which reagent is commonly used?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
AS practical skills and required practical activities
Question
- A. Benedict's solution
- B. Bromine water
- C. Acidified potassium dichromate
- D. Silver nitrate
Answer
Benedict's solution
Explanation
The correct option is Benedict's solution. Benedict's solution is the best answer because it directly supports the AQA A-Level Chemistry objective to required practical 6: test for alcohol, aldehyde, alkene and carboxylic acid functional groups. This reasoning is anchored to AS required practical activities in AS practical skills and required practical activities, and it separates required practical from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.
Common mistake
Identifying Functional Groups
Students often confuse the tests for alcohols and aldehydes, leading to incorrect identification of functional groups.
To correctly identify functional groups, remember that alcohols can be tested using acidified potassium dichromate, which turns from orange to green, while aldehydes can be tested using Tollens' reagent, which produces a silver mirror. Always state the test used, the observation, and the conclusion about the functional group present.
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