To determine the heat liberated during the polymerization of 1 mol of vinyl chloride, we first need to find out how many moles of vinyl chloride are present in the polymer with an average molecular weight of 50,000 g/mol.The molecular weight of vinyl chloride C2H3Cl is:C: 12.01 g/mol 2 atoms = 24.02 g/molH: 1.01 g/mol 3 atoms = 3.03 g/molCl: 35.45 g/mol 1 atom = 35.45 g/molTotal molecular weight of vinyl chloride = 24.02 + 3.03 + 35.45 = 62.50 g/molNow, we can determine the number of moles of vinyl chloride in the polymer:50,000 g/mol polymer / 62.50 g/mol vinyl chloride = 800 moles of vinyl chlorideSince the enthalpy change of polymerization is -121.8 kJ/mol, we can calculate the heat liberated during the polymerization of 1 mol of vinyl chloride:Heat liberated = Enthalpy change of polymerization * moles of vinyl chlorideHeat liberated = -121.8 kJ/mol * 800 molesHeat liberated = -97,440 kJTherefore, the heat liberated during the polymerization of 1 mol of vinyl chloride is -97,440 kJ.