Question detail
Describe a test to identify the presence of alcohols in a sample. Include the expected observation.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Alcohols
Question
Describe a test to identify the presence of alcohols in a sample. Include the expected observation.
Answer
To test for alcohols, add a few drops of acidified potassium dichromate to the sample and warm it gently. If an alcohol is present, the orange solution will turn green due to the reduction of dichromate ions.
Explanation
This question tests the student's understanding of qualitative analysis for alcohols. The answer demonstrates knowledge of the specific reagents and the expected color change, which indicates the presence of an alcohol functional group.
Common mistake
Testing for Alcohols
Students often confuse the test for alcohols with the test for aldehydes, leading to incorrect conclusions about the presence of functional groups.
To correctly test for alcohols, use the appropriate reagent, such as sodium dichromate in dilute sulfuric acid, which will oxidize primary and secondary alcohols, changing color from orange to green. Ensure to write the balanced equation for the reaction: C2H5OH + [O] → CH3COOH + H2O. This shows the oxidation of ethanol to acetic acid.
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