# Hydrogen peroxide decomposes via a pseudo-first order process, with a rate constant of 1.15x10^-3 s-1. How long will it take for 90% of the hydrogen peroxide originally present to decompose?

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### 1 Answer

`2 H_2O_2 -> 2 H_2O + O_2`

`H_2O_2 -> H_2O + O_2`

`rate = k[H_2O_2] ->` pseudo first order reaction

`[A] = [A]_0 e^(-kt)`

if 90% will be decomposed, then:

`[A]_0 = 1`

`[A] = 0.10`

`k =1.15x10^-3 s^-1`

`[0.10] =[1]*e^(-kt) `

`0.1/1 =e^(-kt) `

`ln(0.1) = -kt `

`-2.3026 = -(1.15x10^-3 s^-1) t `

`t = (-2.3026)/(1.15x10^-3 s^-1) `

`t = 2002 s `

`t = 2.0x10^3 s e conds `

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