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Question

Hydrogen gas reduces NO to N₂ in the following reaction:

2H₂(g) + 2NO(g) <—> 2H₂O(g) + N₂(g)

The initial reaction rates of four mixtures of H₂ and NO were measured at 1500°C with the following results:

Experiment: 1

[H₂]₀ (M): 0.212

[NO]₀ (M): 0.136

Initial rate (M/s): 0.0367

Experiment: 2

[H₂]₀ (M): 0.212

[NO]₀ (M): 0.272

Initial rate (M/s): 0.0737

Experiment: 3

[H₂]₀ (M): 0.424

[NO]₀ (M): 0.544

Initial rate (M/s): 0.583

Experiment: 4

[H₂]₀ (M): 0.848

[NO]₀ (M): 0.544

Initial rate (M/s): 2.34

The correct rate law for the reaction at 1500°C is

rate = k[H₂]²[NO]

Determine the rate constant for the reaction at 1500°C.

_____ M^-Xs^-1

^{Can someone please help me answer this question please.}

Answer 1

Comparing experiments 1 and 2, we see it is first order in NO

Comparing experiments 3 and 4, we see it is second order in H₂

So, indeed the rate law is

rate = k[H₂]²[NO]

Using any of the experiments, we can solve for k. I'll use experiment 1:

0.0367 M/s = k[0.212 M]²[0.136 M ] = 0.00611 M³ k

k = 0.0367 M/s / 0.00611 M³

k = 6.00 M^-2s^-1