For the gas phase reaction
`PCl_(5)rarrPCl_(3)(g)+Cl_(2)(g)`
which of the following conditions are correct?

Options

A. `DeltaH=0 and DeltaS lt 0`
B. `DeltaH gt 0 and DeltaS gt 0`
C. `DeltaH lt 0 and DeltaS lt 0`
D. `DeltaH gt 0 and DeltaS lt 0`

Answer

B

Explanation

For enthalpy equation , `DeltaH=DeltaE+ n_(g)RT`
For the reaction , `PCl_(5)(g) hArr PCl_(3)(g) + Cl_(2)(g)`
`Deltan_(g)` = product mole- reactant mole `Deltan=2-1=1`
Thus, the value of `DeltaH` is positive or `gt ` 0
`DeltaG=DeltaH-TDeltaS`
For a spontaneous reaction, `DeltaG` must be negative. Since in this reaction `DeltaH` is positive, so for the negative value of `DeltaG, DeltaS` must be positive or `gt 0`
Hence `DeltaH gt 0 , DeltaS gt 0`