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Lactic acid, CH₃CH(OH)CO₂H, causes pain when it builds up in muscles - CIE - A-Level Chemistry - Question 24 - 2014 - Paper 1
Question 24
Lactic acid, CH₃CH(OH)CO₂H, causes pain when it builds up in muscles. Which reagent reacts with both of the –OH groups in lactic acid? A acidified potassium dichroma... show full transcript
Worked Solution & Example Answer:Lactic acid, CH₃CH(OH)CO₂H, causes pain when it builds up in muscles - CIE - A-Level Chemistry - Question 24 - 2014 - Paper 1
Step 1
Which reagent reacts with both of the –OH groups in lactic acid?
Answer
To determine which reagent reacts with both –OH groups in lactic acid, we need to analyze each option:
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Acidified Potassium Dichromate(VI): This reagent is an oxidizing agent that typically reacts with alcohols, but it specifically oxidizes primary and secondary alcohols into carbonyl compounds. It would not react with both –OH groups effectively as it targets only one.
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Ethanol: As a reagent, ethanol does not react with the –OH groups in lactic acid; instead, it is an alcohol itself and does not facilitate a reaction with both hydroxyl groups.
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Sodium: Sodium metal reacts with alcohols to produce alkoxides and hydrogen gas, thus reacting with both –OH groups present in lactic acid. This is a strong reaction and appropriate for the inquiry.
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Sodium Hydroxide: While sodium hydroxide can react with alcohols, its primary role is as a strong base, which may not effectively engage both hydroxyl groups in a significant reaction.
Thus, the correct choice is C sodium, as it is the only reagent that successfully reacts with both hydroxyl groups in lactic acid.