standard enthalpy change of formation－航空百科

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standard enthalpy change of formation

發問:

Please help me to solve these questionsUsing the values of standard enthalpy change of formation given calculate the values of△H for the following reactions:a. the thermal decomposition of BaCO3b. C2H6(g) +Br2(l) ? C2H5Br(l)+ HBr(g)c. C2H4(g) + H2O(l)? C2H5OH(l)d. TiCl4(l) +2Mg(s) ? Ti(s)+2MgCl2(s)e. SO3(l)... 顯示更多 Please help me to solve these questions Using the values of standard enthalpy change of formation given calculate the values of△H for the following reactions: a. the thermal decomposition of BaCO3 b. C2H6(g) +Br2(l) ? C2H5Br(l)+ HBr(g) c. C2H4(g) + H2O(l)? C2H5OH(l) d. TiCl4(l) +2Mg(s) ? Ti(s)+2MgCl2(s) e. SO3(l) + H2O(l) ?H2SO4(l) Thanks!! 20 marks will be given to the best solution!!! Thanks very much!!! 更新: [△Hf/kJmol-1: BaO(s): -997.5; BaCO3(s): -1218.8; CO2(g): -393.5; C2H4(g): +52.3; C2H6(g): -84.6; C2H5Br(l): -92.0; C2H5OH(l): -277.7; HBr(g): -36.2; H2O(l): -285.9; H2SO4(l): -814.0; MgCl2(s): -641.8; TiCl4(l): -804.2; SO3(l): -395.4]

最佳解答:

For any reaction, ΔH = ∑ΔHf(products) - ∑ΔHf(reactants) ===== a. BaCO3(s) → BaO(s) + CO2(g) ΔH = {ΔHf[BaO(s)] +ΔHf[CO2(g)]} - ΔHf[BaCO3(s)] = {(-997.5) + (-393.5)} - (-1218.8) = -172.2 kJ mol-1 ===== b. ΔH = {ΔHf[C2H5Br(l)] +ΔHf[HBr(g)]} - {ΔHf[C2H6(g)] +ΔHf[HBr(g)]} = {(-92.0) + (-36.2)} - {(-84.6) + 0} = -43.6 kJ mol-1 ===== c. ΔH = ΔHf[C2H5OH(l)] - {ΔHf[C2H4(g)] +ΔHf[H2O(l)]} = (-277.7) - {(+52.3) + (-285.9)} = -44.1 kJ mol-1 ===== d. ΔH = {ΔHf[Ti(s)] +2ΔHf[MgCl2(s)]} - {ΔHf[TiCl4(l)] +2ΔHf[Mg(s)]} = {0 + 2(-641.8)} - {(-804.2) + 2(0)} = -479.4 kJ mol-1 ===== e. ΔH = ΔHf[H2SO4(l)] - {ΔHf[SO3(l)] +ΔHf[H2O(l)]} = (-814.0) - {(-395.4) + (-285.9)} = -132.7 kJ mol-1

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