Question

The reaction of hydrogen and iodine monochloride is given as :
$\sf H_2 + 2ICl \longrightarrow 2HCl + I_2$

The reaction is of first order w.r.t to hydrogen and iodine monochloride, following mechanisms are proposed.

Mechanism A :
$\sf H_2 + 2ICl \longrightarrow 2HCl + I_2$

Mechanism b :
$\sf H_2 + ICl \longrightarrow HCl + HI : slow \\ \\ \sf HI + ICl \longrightarrow HCl + I_2 : fast$

Which of the above mechanism(s) are consistent with the given Information about the reaction? ​

Answer 1

Answer

Correct option is

B

II only

According to question the given reaction is first order in H  

2

​

(g) and also first order in ICl(g) so, the slowest (rate determining) step in the reaction should involve H  

2

​

(g) & ICl(g) one mole each.

The mechanism II is seeming consistent with the conditions stated as:-

H  

2

​

(g)+ICl(g)⟶HCl(g)+HI(g)    (slow)

  Rate=K[H  

2

​

][ICl]

& HI(g)+ICl(g)⟶HCl(g)+I  

2

​

(g)   (fast)

Answer 2

According to question the given reaction is first order in H

2

(g) and also first order in ICl(g) so, the slowest (rate determining) step in the reaction should involve H

2

(g) & ICl(g) one mole each.

The mechanism II is seeming consistent with the conditions stated as:-

H

2

(g)+ICl(g)⟶HCl(g)+HI(g) (slow)

Rate=K[H

2

][ICl]

& HI(g)+ICl(g)⟶HCl(g)+I

2

(g) (fast)