Question

8. The rate constant for the reaction below is 6.2 x 10−5 mol L−1s−1. If the initial concentration of A is 0.0500 M, what is its concentration after 115 s?

Answer 1

Answer:

The concentration after 115 seconds is 0.0496 M

Explanation:

Applying integrated rate law for a first-order reaction, we will have;

$[A]_t = [A]_0e^{-kt}$

where;

$[A]_t$ is the concentration at a time t

$[A]_0$ is the initial concentration

k is the rate constant for the reaction

t is the given time

Given;

$[A]_0$  = 0.05 M

k = 6.2 x 10⁻⁵ mol L⁻¹s⁻¹

t = 115 seconds

Substitute these values and solve for $[A]_t$

$[A]_t = [A]_0e^{-kt} = (0.05)*e^{-(6.2X10^{-5}*115)}$

$[A]_t = (0.05)(0.9929) =0.0496 M$

Therefore, the concentration after 115 seconds is 0.0496 M