Chemistry

Chemistry

Problem

Using the average bond energies in the table, determine which of the following combustion reactions releases the greatest amount of energy per mole of fuel burned at 298 K298\,\text{K}. Average bond energies (kJ mol−1\text{kJ mol}^{-1}): C–H 413, C–C 347, C=C 614, C≡C 839, O=O 498, C=O (in CO2CO_2) 799, O–H 463 A. CH4(g)+2 O2(g)→CO2(g)+2 H2O(l)CH_4(\text{g}) + 2\,O_2(\text{g}) \to CO_2(\text{g}) + 2\,H_2O(\text{l}) B. C2H4(g)+3 O2(g)→2 CO2(g)+2 H2O(l)C_2H_4(\text{g}) + 3\,O_2(\text{g}) \to 2\,CO_2(\text{g}) + 2\,H_2O(\text{l}) C. C2H2(g)+212 O2(g)→2 CO2(g)+H2O(l)C_2H_2(\text{g}) + 2\frac{1}{2}\,O_2(\text{g}) \to 2\,CO_2(\text{g}) + H_2O(\text{l}) D. All three reactions release approximately the same energy per mole of fuel. Which choice correctly identifies the most exothermic reaction per mole? a) combustion of CH4CH_4 b) combustion of C2H2C_2H_2 c) combustion of C2H4C_2H_4 d) all approximately equal

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