Iodine atoms combine to form molecular iodine in the gas phase

I $($g$)+$ I $($g$)->$ I$2($g$)$

This reaction follows second$-$order kinetics and has the high rate constant $7\mathrm{.}0$ x $109/$M$.$s at $23$oC$.$ If the initial concentration of I was $0\mathrm{.}086$ M$,$ calculate the concentration after $2\mathrm{.}0$ min?