Joana S. The combustion of ethane (C2H6) produces carbon dioxide and steam. 2C2H6(g)+7O2(g)⟶4CO2(g)+6H2O(g) How many moles of CO2 are produced when 5.95 mol of ethane is burned in an excess of oxygen? 1 Expert AnswerBond Energies obtained from: http://science.jrank.org/pages/984/Bond-Energy.htm… The following values will vary depending on the source; C-C 347 kJ/mole; C-H 414 kJ/mole; O-H 464 kJ/mole ; O=O 498 kJ/mole It takes energy to break bonds and energy is released when bonds are formed. Ethane has 1 C-C bond ; 1(347 ) 347 kJ/mole Ethane has 6-C-H bonds; 6(414) = 2484 kJ/mole Break the bonds of 1 mole of C2H6 = 2831 kJ 2 moles of ethane in balanced equation: 2(2831 kJ) = 5662 kJ Break 7 O=O bonds = 7(498 ) = 3486 Total energy to break all bonds: 5662 + 2486 = +9148 kJ 2C=O bond formed in CO2 = 2(799) = 1598 kJ/mole 4 moles of CO2 = 4(1598) = 6392 2(O-H) bonds in H2O = 2(464) = 928 kJ/mole 6 moles of H2O = 6(928 kJ) = 5568 Total energy released = 6392 + 5568 = 11,960 kJ The sign of this energy is -11,960 since it is exothermic. Energy change for 2 moles of ethane = -11,960 + 9148 = -2812 kJ ΔHrxn = -2812 kJ
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