Question

At 25 oC, the rate constant for the first-order decomposition of a pesticide solution is 6.40 x 10-3 min-1. If the starting concentration of pesticide is 0.0314 M, what concentration will remain after 62.0 minutes at 25 oC? 3.12 x 10-2 M 47.4 M 2.11 x 10-2 M 4.67 x 10-2 M 8.72 M

Answer 1

`2.11\ * 10^(-2)` is the correct answer to the given question.

Step-by-step explanation:

Given k=6.40 x 10-3 min-1.

According to the first order reaction .

The concentration of time can be written as

`[\ A\ ]\ = \ [\ A_(0)\ ] * e \ ^\ {-kt}`

Here
`[\ A\ ]_(0)` = Initial concentration.

So
`[\ A\ ]_(0)= 0.0314 M`

Putting this value into the above equation.

`0.0314 \ *\ e^{6.40 x 10^(-3) \ * \ 62.0 }`

=0.211 M

This can be written as

`=\ 2.11 *\ 10^(-2)`