Use the bond enthalpies given to estimate the heat released when ethene, CH₂=CH₂, Reacts with hydrogen to give CH₃CH₃.Bond enthalpies ( kJ.mol^-1): C-H,412; C-C,348; C=C,612; C-Br,276; H-H,436. A) 124 kJ.mol^-1 B) 342 kJ.mol^-1 C) 288 kJ.mol^-1 D) 148 kJ.mol^-1 E) 560 kJ.mol^-1

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Quizplus · Accepted Answer

The heat released is equal to the difference between the bond enthalpies of the reactants and the products. The bond enthalpies of the reactants are:C-H: 412 kJ/mol x 4 = 1648 kJ/molC-C: 348 kJ/molC=C: 612 kJ/molThe bond enthalpies of the products are:C-H: 412 kJ/mol x 6 = 2472 kJ/molC-C: 348 kJ/molThe heat released is therefore:1648 kJ/mol + 348 kJ/mol + 612 kJ/mol - 2472 kJ/mol - 348 kJ/mol = 124 kJ/mol

Use the Bond Enthalpies Given to Estimate the Heat Released