Phosphorous pentachloride dissociates as follows (in a closed reaction vessel):
`PCI_(5)(g)hArrPCI_(3)(g)+CI_(2)(g)`
If the total pressure at equilibrium on the reaction mixture is P and the degree of dissociation of `PCI_(5)` is x, the partial pressure of `PCI_(3)` will be

Options

A. `((x)/(x+1))P`
B. `((x)/(1-x))P`
C. `((2x)/(1-x))P`
D. `((x)/(x-1))P`

Answer

A

Explanation

`{:(,PCl_(5)(g),hArrPCl_(3)(g),+Cl_(2)(g)),("Initial (moles)",I,0,0),("Change (moles)",1-x,+x,+x),("Equilibrium (moles)",1-x,x,x):}`
Total moles `=n_(PCl_(5))+n_(PCl_(3))+n_(Cl_(2))`
`=(1-x)+(x)+(x)`
`=1+x`
Partial pressure of `PCl_(3)`
`=("Mole fraction of" PCl_(3))xx("Total pressure of" PCl_(3))`
`=((x)/(1+x))P`