Given the reaction 2NO(g) + 2H2(g) → N2(g) + 2H2O(g), which of the following represents the correct rate law if the reaction is first order in H2 and second order in NO?

• A. Rate = k[NO]^2[H2]
• B. Rate = k[NO][H2]^2
• C. Rate = k[NO][H2]
• D. Rate = k[NO]^2[H2]^2

Answer: (A)

Verified step by step guidance

1. Identify the order of the reaction with respect to each reactant. The problem states that the reaction is first order in H2 and second order in NO.
2. Recall that the rate law for a reaction is expressed as Rate = k[A]^m[B]^n, where k is the rate constant, [A] and [B] are the concentrations of the reactants, and m and n are the orders of the reaction with respect to each reactant.
3. Apply the given orders to the rate law expression. Since the reaction is first order in H2, the exponent for [H2] will be 1. Since the reaction is second order in NO, the exponent for [NO] will be 2.
4. Construct the rate law using the identified orders: Rate = k[NO]^2[H2]^1.
5. Simplify the expression by removing the exponent of 1, as it is implied: Rate = k[NO]^2[H2].