Question

The rate constant for a certain reaction is k = 5.30×10−3 s −1 . If the initial reactant concentration was 0.900 M , what will the concentration be after 13.0 minutes?

Answer 1

The rate constant for a certain reaction is k = 5.30×10−3 s −1 . If the initial reactant concentration was 0.900 M , what will the concentration be after 13.0 minutes?

Solution

Unit of rate constant shows that reaction is first order.

First order integrated rate equation

Ln ([A]t/[A]0) = - kt

Here At and A0 are the concentrations at time t and initial concentration respectively.

k is rate constant , t is the time.

Lets plug given values to get the At

ln ( [A]t / 0.900 ) = - 5.30 E-3 x 13.0 x 60 x

take exp of both side

[A]t/0.900 = exp ( -5.30 E-3 x 13.0 x 60 )

[A]t = 0.01442 M

So the concentration at time 13.0 minute = 0.0144 M