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Which reagent will give similar results with both butanone and butanal? A - CIE - A-Level Chemistry - Question 22 - 2010 - Paper 1
Question 22
Which reagent will give similar results with both butanone and butanal? A. acidified aqueous potassium dichromate(VI) B. an alkaline solution containing complexed C... show full transcript
Worked Solution & Example Answer:Which reagent will give similar results with both butanone and butanal? A - CIE - A-Level Chemistry - Question 22 - 2010 - Paper 1
Step 1
Which reagent will give similar results with both butanone and butanal?
Answer
To determine which reagent gives similar results with both butanone (a ketone) and butanal (an aldehyde), we need to consider their reactivity with the reagents listed.
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Acidified aqueous potassium dichromate(VI): This reagent oxidizes aldehydes to carboxylic acids but does not oxidize ketones (like butanone) under mild conditions. Therefore, this is not the right reagent.
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Alkaline solution containing complexed Cu<sup>2+</sup> ions (Fehling's solution): This reagent reacts with aldehydes to form a red precipitate of copper(I) oxide but does not react with ketones. This rule out this option as well.
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An aqueous solution containing [Ag(NH<sub>3</sub>)<sub>2</sub>]<sup>+</sup> (Tollens' reagent): Tollens' reagent can oxidize aldehydes to carboxylic acids, while ketones generally do not react. Thus, this reagent will also not provide similar results for both compounds.
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2,4-dinitrophenylhydrazine reagent: This reagent reacts with both aldehydes and ketones to form yellow or orange hydrazones, which means it will give similar results for both butanone and butanal.
Therefore, the correct answer is D. 2,4-dinitrophenylhydrazine reagent.