The initial rate of hydrolysis of methyl acetate 1 M by a weak acid ( HA ,   1 M ) is 1 / 100 th of…

The initial rate of hydrolysis of methyl acetate1M by a weak acid (HA, 1M) is 1/100th of that by a strong acid HX, 1M, at 25°C. The Ka of HA is
  1. 1 × 10 - 4
  2. 1 × 10 - 5
  3. 1 × 10 - 6
  4. 1 × 10 - 3

Solution

CH 3 COOCH 3 + H 2 O → H + CH 3 COOH + CH 3 OH ​
Rate Law ⇒ k MA H + (as water is present in large excess)
MA = 1 M in both cases
H + Strong = 1 M in presence of strong acid HX.
H + weak = K a . c = K a in the presence of weak acid HA.
Initial rate (weak acid) = k 1 K a ...... (I)
Initial rate (strong acid)   =  k 1 1 ...... (II)
I II = K a = 1 1 0 0 = 1 0 - 2
K a = 1 × 1 0 - 4 .

Asked in: JEE Advanced 2013 (Paper 1)

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