In: Chemistry
Phosphorus pentachloride decomposes according to the chemical equation PCL5(g)<--->PCl3(g)+Cl2(g). Kc=1.80 at 250 C. A 0.220 mol sample of PCl5(g) is injected into an empty 3.00 L reaction vessel held at 250 �C. Calculate the concentrations of PCl5(g) and PCl3(g) at equilibrium.
PCl5 molarity = 0.220 / 3 =0.0733
PCl5 <-------------------------> PCl3 + Cl2
0.0733 0 0 ---------------------> initial
-x +x +x -----------------> changed
0.0733-x x x ---------------------> equilibrium
Kc = [PCl3] [Cl2] / [PCl5]
1.80 = x^2 / 0.0733 -x
x^2 + 1.80 x - 0.132 = 0
x = 0.0705
equilibrium concentrations :
[PCl5] = 0.0733 -0.07 = 0.0033 M
[PCl3] = x = 0.0705 M