Q. The reaction of hydrogen and iodine monochloride is given as: H₂(g) + 2ICl(g) → 2HCl(g) + I₂(g) The reaction is of first order with respect to H₂(g) and ICl(g), following mechanisms were proposed. Mechanism A: H₂(g) + 2ICl(g) → 2HCl(g) + I₂(g) Mechanism B: H₂(g) + ICl(g) → HI(g) ; slow HI(g) + ICl(g) → HCl(g) + I₂(g) ; fast Which of the above mechanism(s) can be consistent with the given information about the reaction?
A) A and B both
B) neither A nor B
C) A only
D) B only
Explanation
[Solution from source] The observed rate law is rate = k[H₂][ICl]. Mechanism A, as a single step, would be second order in ICl. In mechanism B the slow step H₂ + ICl gives exactly rate = k[H₂][ICl], so only B is consistent. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.