Given the rate law you determined for the reaction 2NO + O2 → 2NO2, which of the following expressions correctly represents the rate of the reaction if the rate law is rate = k[NO]^2[O2]?

• A. rate = k[NO][O2]
• B. rate = k[NO][O2]^2
• C. rate = k[NO]^2[O2]
• D. rate = k[NO]^2

Answer: (C)

Verified step by step guidance

1. Understand that the rate law expresses the rate of a reaction as a function of the concentration of reactants raised to specific powers, which are determined experimentally.
2. Given the rate law rate = k[NO]^2[O2], identify the order of the reaction with respect to each reactant: the reaction is second order in NO and first order in O2.
3. Compare each given expression to the determined rate law to see if the powers of the concentrations match: for example, rate = k[NO][O2] is first order in NO, which does not match the given rate law.
4. Recognize that the correct rate law must have the concentration of NO squared and the concentration of O2 to the first power, exactly as in rate = k[NO]^2[O2].
5. Conclude that among the options, only rate = k[NO]^2[O2] correctly represents the rate of the reaction according to the given rate law.