Question

A 2.90 g sample of an unknown chlorofluorocarbon is decomposed and produces 573 mL of chlorine gas at a pressure of 754 Torr and a temperature of 298 K. What is the percent chlorine (by mass) in the unknown chlorofluorocarbon?

Answer 1

V   = 573ml   = 0.573L

P   = 754torr   = 754/760   = 0.992atm

T   = 298K

PV = nRT

n   = PV/RT

      = 0.992*0.573/0.0821*298   = 0.0232moles

mass of Cl2   = no of moles * gram molar mass

                     = 0.0232*71   = 1.6472g

The percent chlorine in the unknown chlorofluoro carbon   = 1.6472*100/2.9   = 56.8% >>>>answer