Consider the reaction: 2 NO(g) + O2(g) → 2 NO2(g). The experimentally determined rate law is: rate = k[NO]^2[O2]. Which of the following statements is correct regarding the reaction order?

• A. The reaction is first order overall.
• B. The reaction is zero order overall.
• C. The reaction is second order overall.
• D. The reaction is third order overall.

Answer: (D)

Verified step by step guidance

1. Identify the rate law given: \(\text{rate} = k[NO]^2[O_2]\).
2. Determine the order with respect to each reactant by looking at the exponents in the rate law: the order with respect to NO is 2, and the order with respect to \(O_2\) is 1.
3. Calculate the overall reaction order by summing the individual orders: overall order = 2 (from NO) + 1 (from \(O_2\)).
4. Interpret the overall order: the sum represents the total order of the reaction, which indicates how the rate depends on the concentration of all reactants combined.
5. Conclude that since the sum of the exponents is 3, the reaction is third order overall.