Time dependent Mass and Energy balance of CSTR

Consider CSTR reactor with the simple reaction a $$ product occurs, where a is the reactant.

Derive the equation with appropriate variables for the $2^{nd}$ order reaction of reactant $A.$ All the

variables should be defined clearly and all the assumptions should be made clearly.

$($a$)$ Time$-$dependent mass balance for CSTR

$($b$)$ Time$-$dependent energy balance for CSTR