Question

the rate law for a reaction is rate =kab. which one of the following statements is false? a) the reaction is first order overall. b) the reaction is first order in a. c) the reaction is first order in b. d) k is the reaction rate constant

Explanation:

1. Recall the rate law and reaction order concepts: The rate law is given as \(\text{rate} = k[\text{A}][\text{B}]\).

• The order with respect to a reactant is the exponent of its concentration in the rate law. For \([\text{A}]\) and \([\text{B}]\), the exponents are 1 (since they are to the power of 1, even though not written), so the reaction is first order in \(\text{A}\) (statement b is true), first order in \(\text{B}\) (statement c is true), and the overall order is the sum of the exponents (\(1 + 1=2\)), so overall second order.
• \(k\) is the rate constant (statement d is true).
• Statement a says the reaction is first order overall, but we just found the overall order is 2, so statement a is false.

Answer:

a) The reaction is first order overall.