The equilibrium composition for the reaction is -
PCl30.20+Cl2(g)0.10⇌PCl5(g)0.40 moles/litre
If 0.20 mole of Cl2 is added at same temp. Find equilibrium concentration of PCl5(KC=20).
Pcl3+Cl2(g)↔Pcl5(g)
0.2−x 0.3−x 0.4+x
Kc=20=(0.4+x)(0.2−x)(0.3−x)
∴20=0.4+x0.06−0.5x+x2
∴20x2−11x+0.8=0
∴x=0.08
∴ Concentration of Pcl5=0.4+0.08=0.48