Using the following data, determine the order of the reaction with respect to [NO₂^–].

Data Table for Three Experiments

Experiment	Initial [NH4+]	Initial [NO2]	Initial rate (M/s)
Experiment 1	0.24 M	0.10 M	7.2 × 10-6 M/s
Experiment 2	0.12 M	0.10 M	3.6 × 10-6 M/s
Experiment 3	0.12 M	0.15 M	5.4 × 10-6 M/s

• A. 0
• B. ½
• C. 1
• D. 2
• E. 3

Answer: (C)

Verified step by step guidance

1. Identify the rate law expression for the reaction, which is typically in the form: Rate = k[NH4+]^m[NO2-]^n, where k is the rate constant, m is the order with respect to NH4+, and n is the order with respect to NO2-.
2. Examine the data from the experiments to determine how changes in the concentration of NO2- affect the initial rate of the reaction, while keeping the concentration of NH4+ constant.
3. Compare Experiment 1 and Experiment 2: The concentration of NH4+ is halved from 0.24 M to 0.12 M, while the concentration of NO2- remains constant at 0.10 M. Observe that the initial rate is also halved from 7.2 × 10^-6 M/s to 3.6 × 10^-6 M/s. This suggests that the reaction is first order with respect to NH4+.
4. Compare Experiment 2 and Experiment 3: The concentration of NH4+ remains constant at 0.12 M, while the concentration of NO2- increases from 0.10 M to 0.15 M. Observe that the initial rate increases from 3.6 × 10^-6 M/s to 5.4 × 10^-6 M/s. Calculate the factor by which the concentration of NO2- increases and the factor by which the rate increases to determine the order with respect to NO2-.
5. Use the relationship between the change in concentration and the change in rate to solve for n in the rate law expression. If the rate increases by the same factor as the concentration, the reaction is first order with respect to NO2-. If the rate increases by a greater factor, the reaction may be of higher order.