The rate of the chemical reaction involving two substances, A and B, is measured. It is found that if the initial concentration of A used is doubled, keeping the B concentration the same, the rate doubles. If the concentrations of both A and B are doubled, the rate is eight times that measured in the first experiment. The rate law for this reaction is rate =

Question

Quizplus · Accepted Answer

The first statement indicates that the rate is proportional to the concentration of A, so we can write rate = k[A]^x[B]^y, where x is the order with respect to A and y is the order with respect to B. From the second statement, if [A] is doubled and [B] is constant, the rate doubles, which means that x=1. From the last statement, if [A] and [B] are both doubled, the rate increases by a factor of 8, which means rate= k[A]^1[B]^1 * 8 = 8k[A][B].

Combining these results, rate = k[A][B], which is equivalent to choice C.

The Rate of the Chemical Reaction Involving Two Substances, a and B