Question

Experiment Initial Concentration [NO] (mol L−1) Initial Concentration, [H2] (mol L−1) Initial Rate of Formation of N2 (mol L−1 min−1)

1 0.0060 0.0010 1.8 × 10⁻⁴
2 0.0060 0.0020 3.6 × 10⁻⁴
3 0.0010 0.0060 0.30 × 10⁻⁴
4 0.0020 0.0060 1.2 × 10⁻⁴

What is the rate law for this reaction based on the given experimental data?

a) Rate = k[NO]

b) Rate = k[H₂]

c) Rate = k[NO]²[H₂]

d) Rate = k[NO][H₂]²

Answer 1

The rate law for this reaction, based on the given experimental data, is determined to be Rate = k[NO]²[H2], indicating the reaction is second order with respect to NO and first order with respect to H2. The correct option is c).

Step-by-step explanation:

To determine the rate law of a reaction from experimental data, we analyze how the rate of reaction changes with varying concentrations of the reactants.

By examining experiments 1 and 2, where the concentration of [H2] is doubled while [NO] is held constant, we can see that the initial rate doubles as well (1.8 × 10⁻⁴ to 3.6 × 10⁻⁴). This implies that the reaction is first order with respect to [H2], because the rate changes in direct proportion to the concentration of H2.

Comparing experiments 3 and 4, where the concentration of [NO] is doubled while [H2] is held constant, leads to the initial rate quadrupling (0.30 × 10⁻⁴ to 1.2 × 10⁻⁴). This indicates that the reaction is second order with respect to [NO], as the rate changes by the square of the change in concentration of NO.

Conclusion

Therefore, the rate law for this reaction is Rate = k[NO]²[H2], answer choice (c).