The degree of dissociation is `0.4` at `400 K` and `1.0` atm for the gaseous reaction
`PCl_(5) hArr PCl_(3)+Cl_(2)`
assuming ideal behaviour of all gases, calculate the density of equilibrium mixture at `400 K` and `1.0` atm (relative atomic mass of P is `31.0` and of Cl is `35.5`).

Explanation

`{:(,PCl_5 hArr , PCl_3 + , Cl_2),("Initial conc.", 1,0,0),("Equi. Conc." , 1-0.4 , 0.4 , 0.4):}`
=0.6
Total numbers of moles after dissociation =0.6+0.4+0.4 =1.4
Now, `V=(nRT)/p`
`(1.4xx0.082xx400)/1` = 45.92 litre
Density = `"Mol. wt."/"Volume"`
Mol. wt. of `PCl_5` =31 + 35.5 x 5 =208.5
`therefore` Density =`208.5/45.92=4.54 "g litre"^(-1)`