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An organic compound will deccolourise dilute acidified aqueous potassium manganate(VII) on warming, but will not deccolourise bromine water - CIE - A-Level Chemistry - Question 30 - 2012 - Paper 1
Question 30
An organic compound will deccolourise dilute acidified aqueous potassium manganate(VII) on warming, but will not deccolourise bromine water. What could the organic ... show full transcript
Worked Solution & Example Answer:An organic compound will deccolourise dilute acidified aqueous potassium manganate(VII) on warming, but will not deccolourise bromine water - CIE - A-Level Chemistry - Question 30 - 2012 - Paper 1
Step 1
What could the organic compound be?
Answer
To determine which compound decoulorises dilute acidified potassium manganate(VII) while not affecting bromine water, we analyze each option:
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Butane (A): This is an alkane. Alkanes do not react with potassium manganate(VII) and will also not decolorise bromine water; therefore, it is not the correct answer.
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Ethanol (B): This is an alcohol. Ethanol can react with potassium manganate(VII) and cause a color change, particularly when heated, as it is easily oxidized to ethanal or further to acetic acid. Ethanol does not decolorise bromine water, making this a strong candidate.
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Ethene (C): This is an alkene. Alkenes react with potassium manganate(VII) to produce a diol and will indeed decolorise bromine water, as they are reactive; thus, it cannot be the answer.
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Ethanoic acid (D): This is a carboxylic acid. Ethanoic acid will not react with potassium manganate(VII) in the same manner to produce a color change without further oxidation; however, it is not likely to not affect bromine water.
Based on the analysis, the correct answer is B. ethanol, as it meets the criteria of decoulorising potassium manganate(VII) upon warming and does not participate in the reaction with bromine water.