Question

The isomerization of methyisocyanide, CH3NC, to acetonitrile, CH3CN, is a first-order reaction. If 2.56 mg of CH3NC is present initially, and 1.89 mg is present after 474 min at 230 °C, what is the value of the rate constant, k?Assume the volume is constant. min-1

Answer 1

To solve this question we will use the integrated rate late law for first order reaction:

`\begin{gathered} ln[A]=-kt+ln[A]_0 \\ [A]:concentration\text{ }of\text{ }A\text{ }at\text{ }certain\text{ }time=1.89mg \\ k:rate\text{ }constant=x \\ t:time=474\text{ }mins \\ [A]_0:initial\text{ }concentration=2.56mg \end{gathered}`

By substituting the values we have to determine the unknown we get:

`\begin{gathered} ln1.89=-k*474min+ln2.56 \\ (0.637-0.940)/(-474min)=k \\ k=6.392*10^(-4)\text{ }min^(-1) \end{gathered}`

Answer: Rate constant k is 6.392x10^-4 per min.