NEET2008ChemistryHaloalkanes and HaloarenesActual
For the gas phase reaction, PCl ₅(g) PCl ₃(g)+ Cl ₂(g) which of the following conditions are correct?
Options
- AH=0 and S < 0
- BH>0 and S>0
- CH < 0 and S < 0
- DH>0 and S < 0
Correct answer
B. H>0 and S>0
Step-by-step solution
Key Idea : H= E+ n R T n= number of moles of product - number of moles of reactants G= H-T S For a spontaneous process G must be negative. PCl ₅( ~g ) PCl ₃( ~g )+ Cl ₂( ~g ) In this reaction n=2-1=1 Thus, H is positive, i e,>0 If H is positive, then to maintain the value of G negative, S should be positive, i e, S>0 .