$7\mathrm{.}1$ The following reaction is carried out in a $10-$L aqueous solution in a stirred

tank

$A+B=>AB$

At the outset of the reaction the reagents A and $B$ are added to the

reactor in equal $1-$mole quantities. After $10$ minutes the concentration of

$AB$ in the reactor is measured as $5$mmo$\frac{l}{L}.$ Determine an appropriate

rate constant. State all assumptions made in arriving at your answer.