Enthalpy of Polymerization Calculation for Ethylene

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The discussion focuses on calculating the enthalpy of polymerization for ethylene to linear polyethylene at 298K using bond dissociation energies. The initial calculation attempted to use the bond enthalpies for C=C and C-C bonds, resulting in an incorrect value of 259 kJ/mol. Participants are asked to clarify the symbols used in the calculation and provide guidance on the correct approach. The importance of accurately accounting for all bond changes during polymerization is emphasized. The thread seeks to resolve the misunderstanding and arrive at the correct enthalpy value.
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Homework Statement


The polymerization of ethylene to linear polyethylene is represented by the following reaction
nCH_{2}=CH_{2} \rightarrow (-CH_{2}-CH_{2}-)_{n}
where n=large integer value
Calculate the enthalpy of polymerization per mol of ethylene at 298K if average bond enthalpies of bond dissociation for C=C and C-C are 590 and 331kJ/mol respectively

Homework Equations



The Attempt at a Solution



For one mole
ΔH_{poly} = BDE of C=C+4\times BDE C-H - BDE of C-C - 4\times BDE C-H
=590-331
=259

But this is not correct.
 
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Please elaborate on the meaning of your symbols.
 

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