Final answer:
To calculate ΔHrxn for the hydrogenation reaction, we can use average bond energies. The bond energies can be found using average bond energies for the reactants and products. We can calculate the difference in energy between the bonds broken and the bonds formed to get ΔHrxn.
Step-by-step explanation:
To calculate ΔHrxn for the hydrogenation reaction H₂C=CH₂(g)+H₂(g)→H₃C−CH₃(g), we can use average bond energies. First, we need to break the bonds in the reactants and then form the bonds in the products. The bond energies can be found using average bond energies. The bond energy for the C=C double bond in ethene (H₂C=CH₂) is 614 kJ/mol, and the bond energy for the H-H bond is 436 kJ/mol. The bond energy for the C-C single bond in ethane (H₃C-CH₃) is 348 kJ/mol and the bond energy for the H-C bond is 413 kJ/mol.