Question

The decomposition of hydrogen peroxide follows first order kinetics and has a rate constant of 2.54 x 10-4 s-1 at a certain temperature. If the concentration of hydrogen peroxide is 0.321 M after 855 s , what was the initial concentration of hydrogen peroxide at this temperature

Answer 1

Answer:

$[A]_0=0.400M$

Explanation:

Hello.

In this case, since the first-order reaction is said to be linearly related to the rate of reaction:

$r=-k[A]$

Whereas [A] is the concentration of hydrogen peroxide, when writing it as a differential equation we have:

$\frac{d[A]}{dt} =-k[A]$

Which integrated is:

$ln(\frac{[A]}{[A]_0} )=-kt$

And we can calculate the initial concentration of the hydrogen peroxide as follows:

$[A]_0=\frac{[A]}{exp(-kt)}$

Thus, for the given data, we obtain:

$[A]_0=\frac{0.321M}{exp(-2.54x10^{-4}s^{-1}*855s)}$

$[A]_0=0.400M$

Best regards!