The isomerization of cyclopropane to form propene is a first-order reaction. At 760 K, 85% of a sample of cyclopropane changes to propene in 79.0 min. Determine the rate constant for this reaction at 760 K.

Question

The isomerization of cyclopropane to form propene is a first-order reaction.  At 760 K, 85% of a sample of cyclopropane changes to propene in 79.0 min. Determine the rate constant for this reaction at 760 K.

Quizplus · Accepted Answer

The reaction is first order, meaning that the decay of cyclopropane is proportional to the concentration of cyclopropane. We can use the following equation:

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

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

We know that at 760 K, 85% of the cyclopropane changes to propene in 79.0 min, meaning that [A]0 = 1 and [A]t = 0.15. We can plug these values into the equation to find k:

ln(0.15/1) = -k(79.0 min)
k = 2.40 x 10^-2 min^-1

Therefore, the correct answer is choice E.

The Isomerization of Cyclopropane to Form Propene Is a First-Order