At some temperature and under a pressure of 4 atm, PCl5 is 10% dissociated. Calculated the pressure at which PCl5 will be 20% dissociated temperature remaining same.
The correct option is A 0.96 atm Let initially 100 moles were present and after 10% dissociation at equilibrium only 90% are remaining. At 4 atm pressure and 10% dissociation. PCl5PCl3Cl2Equibm mole901010Equilibrium partial pressures90110×410110×410110×4 Hence, Kp=PPCl5PPCl5PPCl5=499 At 20 % dissociation, PCl5PCl3Cl2Equilibrium mole802020Equilibrium partial pressures80120×P20120×P20120×PKp=PPCl3PCl2PPCl5=124×P Thus, 124×P=499orP=0.96 atm