Answer to Question #137741 in General Chemistry for Joan

Question

The reaction mechanism is

2A + 2S ⇌ 2A*S

B+S ⇌ B*S

2A*S + B*S ⇌ C*S+2S

C*S ⇌ C+S

Derive a rate law assuming:

A) The surface reaction is rate-limiting.

B) The adsorption of A is rate-limiting.

C) The desorption of C is rate limiting.

Answer 1

A) The decomposition reaction occurs uniformly across the surface sites at which molecule A may be adsorbed and is not restricted to a limited number of special sites.

B) The products are very weakly bound to the surface and, once formed, are rapidly desorbed.

C) The rate determining step (rds) is the surface decomposition step