Chemistry 102: Kinetics: Concentration

Question

The reaction 2A → A₂​​​​​ was experimentally determined to be second order with a rate constant, k, equal to 0.0265 M^–1min^–1. If the initial concentration of A was 2.25 M, what was the concentration of A (in M) after 180.0 min?

Answer 1

Using the integrated rate law for a second order reaction:

1/[A]t = kt + 1/[A]0

Step 1) make sure units do not need to be converted.

Step 2) Fill in the given for the above equation

1/[A]t = (0.0265M-1 min-1)(180min) + 1/2.25M)

Step 3)

solve for [A]t

1[A]t = 4.77 + 0.44

1/[A]t = 5.21

[A]t = 0.192 M