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Calculate the enthalpy of combustion of ethylene (gas) to form CO2 (gas) and H2O (gas) at 298 K and 1 atmospheric pressure. The enthalpies of formation of CO2 , H2O and C2H4 are –393.5, –241.8, + 52.3 kJ per mole respectively. |
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Answer» We are given : (i) C (s) + O2 (g)→ CO2 (g), ΔH°1 = – 393.5 kJ mol–1 (ii) H2(s) +1/2 O2 (g) →H2O(g) ΔH°2 = – 241.8 kJ mol–1 (iii) 2C (s) + 2H2 (g) → C2H4 (g),ΔH°3 = + 52.3 kJ mol–1 We aim at : C2H4 (g) + 3O2 (g) → 2CO2 (g) + 2H2O(g) ΔH = – ΔH3 + 2ΔH1 + 2ΔH2 = –1322.9 kJ mol–1 |
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