Question

Rate for a zero order reaction is `2xx10^(-2) mol L^(-1) s^(-1)` . If the concentration of the reactant after 25s is `0.5M`, the initial concentration must have been
A. `12.5M`
B. `0.5M`
C. `1.0M`
D. `1.25M`

Answer 1

Correct Answer - C
For a zero order reaction, the rate of the reaction at all concentrations is equal to the rate constant. Integrated rate law for the zeroth order reaction is
`K=([R]_(0)-[R]_(t))/(t)`
or `[R]_(0)=[R]_(t)+Kt`
`=(0.5M)+(2xx10^(-2)Ms^(-1))(25s)`
`=(0.5M)+(0.5M)=1.0M`