The liquid$-$phase reaction: A $+$ B $->$ C follows an elementary rate law and is carried out isothermally in a $200$ L batch reactor heated to $77\backslash$deg C$.$ The initial concentrations of A and B are both $1$ mol$/$L$.$ At $27\backslash$deg C$,$ k $=0\mathrm{.}07$ L$/$mol$$min$,$ and E $=20$ kcal$/$mol$.$ How long does it take to achieve $90\%$ conversion at $77\backslash$deg C$?$