JEE Advanced2013ChemistryIonic EquilibriumActual
The initial rate of hydrolysis of methyl acetate 1 M by a weak acid ( HA , 1 M ) is 1 / 100 th of that by a strong acid HX , 1 M , at 25 ° C . The K a of HA is
Options
- A1 × 10 - 4
- B1 × 10 - 5
- C1 × 10 - 6
- D1 × 10 - 3
Correct answer
A. 1 × 10 - 4
Step-by-step 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 .