Answer
i) $8.7\times10^{-3}$ M/s
ii) $6.0\times10^{-3}$ M/s
Work Step by Step
Average rate of the reaction, $r_{av}$= $-\frac{\Delta [R]}{\Delta t}$ where $\Delta [R]$ is the change in concentration of the reactant and$\Delta t$ is the time taken for the change.
i) Here, $\Delta [R]$= 0.913 M- 1.000 M = -0.087 M.
$\Delta t$ = 10 s- 0 s = 10 s
So $r_{av}=- (\frac{-0.087 M}{10 s}$)= $8.7\times10^{-3}$ M/s
ii) In this case, $\Delta [R]$= 0.637M- 0.697 M = -0.060 M
and $\Delta t$ = (50-40)s= 10s
This gives $r_{av}= -(\frac{-0.060 M}{10 s})$= $6.0\times10^{-3}$ M/s
