If  PCl5(g)is 80% dissociated in to  PCl3(g) and Cl2(g) at 523 k, the vapour density of equilibrium mixture at same temperature is _____?

PCl5(g)⇌PCl3(g)+Cl2(g) Initial number of moles                          1           0            0                                                                 -0.8      +0.8    +0.8 Moles at equilibrium                             0.2         0.8     0.8Total number of moles at equilibrium  = 1.8 According to law of conservation of mass, mass of 1.8 moles gaseous mixture of equilibrium = 208.5 units 1 mole of equilibrium mixture =115.833 units Now VD = Maverage2=115.832=57.92 units