A first-order reaction is 58% complete at the end of 11 min. What is the value of the rate constant?

Question

Quizplus · Accepted Answer

We can use the following equation for a first-order reaction:

ln([A]t/[A]0) = -kt

where [A]t is the concentration of the reactant at time t, [A]0 is the initial concentration, k is the rate constant, and t is time.

If the reaction is 58% complete, then [A]t/[A]0 = 0.42 (100% - 58% = 42%). Also, we are given that t = 11 min.

Substituting these values into the equation, we get:

ln(0.42) = -k(11)

Solving for k:

k = -ln(0.42)/11 = 7.9 × 10-2 min-1

Therefore, the best choice is C, 7.9 × 10-2 min-1.

A First-Order Reaction Is 58% Complete at the End of 11