General Chemistry

Question

The rate constant for the reaction is 0.620 M−1⋅s at 200 ∘C

A⟶products

If the initial concentration of A is 0.00670 M, what will be the concentration after 115 s?

Answer 1

Since we have no information other than the rate constant, we must use the units of the rate constant to determine the order of the reaction. Unfortunately, the units given (M^-1s) do not correspond to any known order. Assuming you have a typo, the units of the rate constant could be

Ms^-1 which would correspond to a zero order reaction, or

M^-1s^-1 which would correspond to a 2nd order reaction.

If a zero order reaction, use [A] = [A]_o - kt

If 2nd order reaction, use 1/[A] = 1/[A]_o + kt

In either case, solve for [A] where [A]_o = 0.00670 M, k = 0.620 units? and t = 115s

If you want/need additional assistance, resubmit the question (or add a comment) with the correct units for k and we'll be glad to run through the calculations for you.