Question

2 H2 + 2 NO → N2 + 2 H2O the observed rate expression, under some conditions, is: rate = k[NO]2 Which of the following mechanisms are consistent with these data? Select all that are True. step 1 H2 + NO → H2O + N (slow) step 2 N + NO → N2 + O (fast) step 3 O + H2 → H2O (fast)

Answer 1

Explanation:

Rate law is defined as the rate of a reaction is directly proportional to the concentration of reactants at constant temperature.

               $Rate \propto [\text{concentration of reactant}]^{n}$

                                  = k $[\text{concentration of reactant}]^{n}$

where,     k = rate constant

                n = order of reaction

For the given reaction, $2H_{2} + 2NO \rightarrow N_{2} + 2H_{2}O$

Hence, its rate will be as follows.

                   Rate = $k[H_{2}][NO]$

Also, it is known that slowest step in a chemical reaction is the rate determining step.

Hence, for the given rate law correct reaction is as follows.

Step 1 : $H_{2} + NO \rightarrow N + H_{2}O$ (slow)

Balancing this equation it becomes $H_{2} + 2NO \rightarrow N_{2}O + H_{2}O$ (slow)

Step 2: $N_{2}O + H_{2} \rightarrow N_{2} + H_{2}O$ (fast)