Asked in NUMS 2019 (cancelled sitting) 2019Moderate

Which of these in an aqueous solution of equal concentration has the lowest pH?

Correct answer: A. Chloroethanoic acid

  • A. Chloroethanoic acid
  • B. Ethanoic acid
  • C. Ethylamine
  • D. Phenol

Explanation

The lowest pH corresponds to the strongest acid. Chloroethanoic acid is a stronger acid than ethanoic acid and phenol due to the electron-withdrawing inductive effect. of the chlorine atom. Ethylamine is a base and will have a pH above 7.

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About Reactivity of Carboxylic Acids

Carboxylic acids show acidic behaviour because their carboxylate ions are resonance-stabilised, and electron-withdrawing groups can change their strength. Reactions include neutralisation, esterification, formation of acid chlorides and amides, reduction, decarboxylation and substitution at the acyl carbon, which differs from the reactions of phenols.

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550 free Carboxylic Acids MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.

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