In the reaction at equilibrium, PCl5(g)⇌PCl3(g)+Cl2(g), they are of equal amount and the total pressure is 3 atm. The equilibrium constant Kp is:
Explanation:
PCl5(g)⇌PCl3(g)+Cl2(g)
Moles of PCl5 at equilibrium =2mol
Moles ofPCl3 at equilibrium =2mol
Moles of Cl2 at equilibrium =2mol
Mole fraction of PCl5:
χ1=2mol2mol+2mol+2mol=13
Mole fraction of PCl3:
χ2=2mol2mol+2mol+2mol=13
Mole fraction of Cl2:
χ3=2mol2mol+2mol+2mol=13
Partial pressure of PCl5 at equilibrium =p1
Partial pressure of PCl3 at equilibrium =p2
Partial pressure of Cl2 at equilibrium =p3
Total pressure at equilibrium =3atm
p1=p×χ1=3atm×13=1atm
p2=p×χ2=3atm×13=1atm
p3=p×χ3=3atm×13=1atm
The equilibrium constant will be given as:
Kp=p2×p3p1=1atm×1atm1atm=1atm
∴ Kp=1atm
Hence correct answer is option A