Question

Calculate the enthalpy change (in kJ/mol) for the polymerization of ethylene to polyethylene, given that the polymerization of 1 mole of ethylene produces 3 moles of polyethylene and the enthalpy change of the reaction is -32 kJ/mol.

Answer 1

The given information is incorrect. The polymerization of ethylene  C2H4  to polyethylene  n[C2H4]  does not produce 3 moles of polyethylene from 1 mole of ethylene. Instead, it involves the formation of a long chain of ethylene units  n moles of ethylene  to form a single polyethylene molecule.The correct way to represent the polymerization reaction is:n C2H4  [-CH2-CH2-]nwhere n is the number of ethylene units in the polyethylene chain.If the enthalpy change for the polymerization of 1 mole of ethylene is -32 kJ/mol, then the enthalpy change for the polymerization of n moles of ethylene would be:H = -32 kJ/mol * nSince the enthalpy change is given per mole of ethylene, the enthalpy change for the polymerization of ethylene to polyethylene remains -32 kJ/mol, regardless of the number of ethylene units in the polyethylene chain.