Answer to Question #141951 in General Chemistry for Princess Mariano

Question

At 575 degrees Celsius nitrous oxide(N2O) decomposes into its elements on a nickel surface. The reaction is zero order with a rate constant of 0.42M/s

A. What will be the concentration of N2O after 5 minutes if it’s initial concentration is 0.084M.

B. What will be the half life of the reaction if the initial concentration of N2O is 0.37 M

Answer 1

A. Manipulating the interpreted rate law of zero-order reactions and substituting values,

$\begin{aligned} [A]&=[A_o​]−kt\\ t &= 5(60)= 300s\\ k &= 0.42M/s\\ [A_o​] &= 0.084M\\ \\ [A]&=0.084 - 0.42(300)\\ [A] &= 0.084 - 126\\ [A] &=-125.916M \end{aligned}$

But since concentration can't be negative, we can safely infer that it's final concentration is 0M.

B. $\begin{aligned} t_\frac{1}{2} &= \dfrac{[A_o]}{2k}\\ \\ t_\frac{1}{2} &= \dfrac{0.37}{2(0.42)}\\ \\ t_\frac{1}{2} &= \dfrac{0.37}{0.84}\\ \\ t_\frac{1}{2} &= 0.44s \end{aligned}$