Question

A reaction has a rate constant of 0.00774 sec-1, how much of the compound (in mol/L) is left after 8.93 sec, if there was 0.652 mol/L at the start? (give answer to 3 decimal places)?
how do you know the order of the reaction???

Answer 1

Answer:

0.608 mol/L compound is left after 8.93 sec

Explanation:

This is a first order reaction because unit of rate constant is $(time)^{-1}$ (or $sec^{-1}$)

For a first order reaction, integrated rate law is-

                  $ln\frac{C_{0}}{C_{t}}=k.t$

where $C_{0}$ is initial concentration of reactant, $C_{t}$ is concentration of reactant after t time and k is rate constant

Here $C_{0}$ = 0.652 mol/L, k = 0.00774 $sec^{-1}$) and t = 8.93 sec

So, $ln(\frac{0.652mol/L}{C_{t}})=0.00774 sec^{-1}\times 8.93 sec$

So, $C_{t}=0.608mol/L$