Chemistry, asked by gauravsiddhartha20, 1 year ago

16.
For reaction
Cl,(aq) + H2S(aq) +S(s) + 2H+(aq) + 2C1- (aq)
rate law is r = K[CI][H,S]
then which of these mechanism is/are
consistent with this rate law :
(A) HS 2 H+ + HS (fast)
CI, + HS- → 2C1- + H+ S (slow)
(B) CI, + H,S → H+ + CI+ CI+ + HS (slow)
CI+ + HS + H+ + C1° + S (fast)

Answers

Answered by shivaninath
1

Explanation:

Consider the reaction:

Cl2(aq)+H2S(aq)→S(s)+2H+(aq)+2Cl−(aq)

The rate equation for this reaction is rate =k[Cl2][H2S].

The rate equation indicates that the reaction is first order in chlorine and first order in hydrogen sulphide.

The mechanism (A) is consistent with this rate equation.

(A) Cl2+H2S→H++Cl−+Cl++HS−    (slow)

      Cl++HS−→H++Cl−+S                     (fast)

The mechanism (A) is not consistent with this rate equation.

(B) H2S⇌H++HS−                                        (fast equilibrium)

      Cl2+HS−→2Cl−+H++S                      (slow)

Based on mechanism (B), the rate equation will be rate =k[Cl2][H2S]1/2 and not rate =k[Cl2][H2S].

From slow step , rate =k′[Cl2][HS−]......(1)

From fast equilibrium step,

K=[

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