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

Answer:

$2.11\ * 10^{-2}$  is the correct answer to the given question.

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

$=\ 2.11 *\ 10^{-2}$