A proposed mechanism for the reaction 2 NO(g) + 2H₂(g) $\rightarrow$ N₂(g) + 2 H₂O(g) is:
Step 1: 2 NO(g) $\rightarrow$ N₂O₂(g) (very fast, reversible)
Step 2: N₂O₂ (g) + H₂ (g) $\rightarrow$ N₂O(g) + H₂O(g) (slow)
Step 3: N₂O(g) +H₂(g) $\rightarrow$ N₂(g) +H₂O(g) (fast) What is the rate law for the overall reaction?

Question

A proposed mechanism for the reaction 2 NO(g) + 2H₂(g)

\rightarrow

N₂(g) + 2 H₂O(g) is:
Step 1: 2 NO(g)

\rightarrow

N₂O₂(g) (very fast, reversible)
Step 2: N₂O₂ (g) + H₂ (g)

\rightarrow

N₂O(g) + H₂O(g) (slow)
Step 3: N₂O(g) +H₂(g)

\rightarrow

N₂(g) +H₂O(g) (fast) What is the rate law for the overall reaction?

Quizplus · Accepted Answer

The rate-determining step is the slowest step, which is Step 2. The rate law for this step is:Rate = k[N₂O₂][H₂]Since Step 1 is a very fast, reversible reaction, it is assumed to be in equilibrium. Therefore, the concentration of N₂O₂ can be expressed in terms of the concentrations of NO and N₂O.K = [N₂O₂]/[NO]²Substituting this expression into the rate law for Step 2, we get:Rate = kK[NO]²[H₂]Therefore, the rate law for the overall reaction is:Rate = k[NO]²[H₂]

A Proposed Mechanism for the Reaction 2 NO(g) + 2H2(g) →\rightarrow→

A Proposed Mechanism for the Reaction 2 NO(g) + 2H₂(g) $\rightarrow$