Question

A reaction was experimentally determined to follow the rate law, Rate = k[A]2 where k = 0.456 s-1M-1. Starting with [A]o = 0.500 M, how many seconds will it take for [A]t = 0.250 M?

Answer 1

If the rate law is rate = k[A]^2 you know it is second order. The integratedrate law for a second order reaction is 1/(A) - 1/(A)o = kt
1/(0.250) - 1/(0.500) = 0.456t. Splve for t in seconds. Post your work if you get stuck.