Question detail
What is the test used to identify the presence of an alcohol in a test-tube reaction?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Organic analysis
Question
- A. Add sodium dichromate and observe for a color change
- B. Add bromine water and observe for decolorization
- C. Add Fehling's solution and observe for a brick-red precipitate
- D. Add silver nitrate and observe for a white precipitate
Answer
Add sodium dichromate and observe for a color change
Explanation
The presence of an alcohol can be identified by adding sodium dichromate, which will oxidize the alcohol and change color from orange to green, indicating the formation of a ketone or aldehyde.
Common mistake
Identifying Functional Groups
Students often confuse the tests for alcohols and aldehydes, leading to incorrect identification.
To correctly identify alcohols and aldehydes, remember that alcohols react with acidified potassium dichromate to produce a color change from orange to green, while aldehydes can be identified using Tollens' reagent, which produces a silver mirror. Use the following steps: 1. For alcohols, apply the formula: color change = orange to green. 2. For aldehydes, apply the formula: silver mirror = positive test. 3. Substitute the observed results into the identification process. 4. Conclude with the correct functional group based on the test results.
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