Chapter 10, Problem 10.5P

The rate law for the hydrogenation (H) of ethylene (E) to form ethane (A) over a cobalt-molybdenum catalyst [Collection Czech. Chem. Commun., 51, 2760 (1988)] is

$-{r^{\prime }}_{\text{E}}=\frac{k{P}_{\text{E}}{P}_{\text{H}}}{1+K_{\text{E}}{P}_{\text{E}}}$

1. (a) Suggest a mechanism and rate-limiting step consistent with the above rate law.
2. (b) What was the most difficult part in finding the mechanism?