What is the Concentration after 30 Seconds?

Question

For the reaction

C4H8 (g) → 2C2H4 (g)

Ea / R = 31513.110 K
A = 4.098 × 1015 s−1

A conversion reaction of the type above takes place at 755 K and an initial concentration of cyclobutane of 0.0350 M What is the concentration of cyclobutane after 30.00 seconds ?

Note: I got an answer, but it's wrong. (=0.006120)
help pls!

Answer 1

OK....Using the Arrhenius equation, you can calculate the rate constant, k. I found that to be 3.058 X 10^-3/s.

Then, I used a form of the integrated rate law given as:

ln[A]=-kt+ln[A]0

(Where ln[A]0 is the initial concentration and ln[A] is the concentration of A at any time, t. With that equation, I found the answer to be 0.0319 M.

What equation did you use to get your answer?