For rate = k [H2] [NO]^2, if [H2] is doubled, the rate increases by what factor?

For rate = k [H2] [NO]^2, if [H2] is doubled, the rate increases by what factor?

• A. 4
• B. 3
• C. 2
• D. 1

Answer: (C)

The rate law shows the reaction is first-order in H2 (rate ∝ [H2]) and second-order in NO (rate ∝ [NO]^2). If [H2] is doubled while [NO] stays the same, the rate is multiplied by 2 from the [H2] term, and the [NO]^2 term remains unchanged. Therefore, the overall rate increases by a factor of 2.

The rate law shows the reaction is first-order in H2 (rate ∝ [H2]) and second-order in NO (rate ∝ [NO]^2). If [H2] is doubled while [NO] stays the same, the rate is multiplied by 2 from the [H2] term, and the [NO]^2 term remains unchanged. Therefore, the overall rate increases by a factor of 2.