MCQ
The correct order of increasing acidic strength is $.........$
  • A
    Phenol $<$ Ethanol $<$ Chloroacetic acid $<$ Acetic acid
  • B
    Ethanol $<$ Phenol $<$ Chloroacetic acid $<$ Acetic acid
  • Ethanol $<$ Phenol $<$ Acetic acid $<$ Chloroacetic acid
  • D
    Chloroacetic acid $<$ Acetic acid $<$ Phenol $<$ Ethanol

Answer

Correct option: C.
Ethanol $<$ Phenol $<$ Acetic acid $<$ Chloroacetic acid
Carboxylic acids dissociate in water to give resonance stabilised carboxylate anions and hydronium ion. That is why carboxylic acids are weaker than mineral acids, but they are stronger acids than alcohols and many simple phenols. Electron withdrawing groups $($halogens$)$ increase the acidity of carboxylic acids by stabilising the conjugate base through delocalisation of the negative charge by inductive and resonance effects. Ethanol is least acidic because the ethoxide ion formed in not resonance stabilised. Thus, the order of increasing acidic strength is $—$
Ethanol $<$ Phenol $<$ Acetic acid $<$ Chloroacetic acid.

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