Which is the correct order of decreasing acidity of phenol, water, ethanol and 2-methylpropan-2-ol?

Awater $>$ phenol $>$ ethanol $>$ 2-methylpropan-2-ol
Bphenol $>$ water $>$ ethanol $>$ 2-methylpropan-2-ol
C2-methylpropan-2-ol $>$ ethanol $>$ water $>$ phenol
Dphenol $>$ ethanol $>$ water $>$ 2-methylpropan-2-ol

Answer: B

Phenol (

p K_{a} \approx 10

) is far more acidic than the rest because the phenoxide ion is resonance stabilised. Alkyl groups donate electrons and hinder solvation of the alkoxide, so acidity falls as water (

15.7

) > ethanol (

16

) > tert-butyl alcohol (

18

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Which is the correct order of decreasing acidity of phenol, water, ethanol and 2-methylpropan-2-ol?

Answer: B

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