Second Order Kinetics

Question

A particular reaction is found to be second order. The reactant has an initial concentration of 2.45 M and a rate constant of 0.00300 M^−1 s^−1. Calculate the final concentration of this reactant after 76.4 seconds have passed.

I know the formula is 1/[A]f=1/[A]i+kt but I think I'm getting my math wrong because of the rate constant having M^-1 and S^-1.

Answer 1

The integrated rate law for a second order reaction is

1/[A] = 1/[A]o + kt which is the same as what you have written.

[A]o = 2.45 M

k = 0.0030 M-1s-1

t = 76.4

[A] = x

1/x = 1/2.45 M + (0.0030 M^-1s^-1)(76.4 s)

1/x = 0.408 M + 0.229 M (the s^-1 and s cancel each other leaving M)

1/x = 0.637 M

x = 1.57 M