For the equalibrium PCl5(g) <--> PCl3(g) + Cl2(g), Kc= 2.0 x 10^1 at240 celcius. If pure PCl5 is placed in a 1.00-l container and allowed to come to equalibrium, and the equalibrium concentration of PCl3(g) is 0.23 M, what is the equalibrium concentration of PCl5(g)?