Nitric oxide and nitrogen dioxide are found in photochemical smog. Nitrogen dioxide is formed from nitrogen monoxide in the exhaust of automobile engines. A possible mechanism for this reaction is given below. What is the rate law predicted by the mechanism?

Reaction:
2NO(g) + O2(g) â†’ 2NO2(g)
Step 1 (fast): NO + NO â†’ N2O2
Step 2 (slow): N2O2 + O2 â†’ 2NO2

A. Rate = k[NO]2
B. Rate = k[NO2]2
C. Rate = k[NO][O2]
D. Rate = k[NO]2[O2]
E. Rate = k[No2]^2/[No]^2[o2]

Question

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Respuesta :

mdimtihaz mdimtihaz · Answer 1 · 2020-04-07T08:55:06+02:00

Answer:

(D) Rate = k[NO]²[O₂]

Explanation:

The rate law predicted by the mechanism

Reaction:

2 NO(g) + O₂(g) →2 NO₂(g)

Step 1 (fast): NO + NO → N₂O₂

Step 2 (slow): N₂O₂ + O₂ → 2 NO₂

According to rate law

rate of reaction is measured from slowest step

[tex]Rate = K[N_{2}O_{2} ] [O_{2} ][/tex] ------------------ (i)

Since N₂O₂ is an intermediate

So we replace intermediate from rate law equation

From step 1 we can write

[tex]k=\frac{[N_{2}O_{2} ]}{[NO]^{2} } \\{[N_{2}O_{2} ]=K[NO]^{2}[/tex]

From equation (i)

∴ Rate = k[NO]²[O₂]