InterviewSolution
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InterviewSolution
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In a fuel cell (device used for producing electricity directly from a chemical reaction )methanol is used as a fuel and oxygen gas is used asan oxidizer. The standard enthalpy of combustion of methanol is `-721kJ mol^(-1)` . The standard free energiesof formation of `CH_(3)OH(l, CO_(2)(g)` and `H_(2)O(l)` are- 166.3 , -394.4 and `- 237 .1 kJ mol^(-1)` respectively. The standard free energy change of the reaction will beA. `-597.8 kJ mol^(-1)`B. `-298 kJmol^(-1)`C. `- 465.2 kJ mol^(-1)`D. `-702.3kJ mol^(-1)` |
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Answer» Correct Answer - d The reaction is `CH_(3)OH(l) + (3)/(2) O_(2)(g) rarr CO_(2)(g) + 2H_(2)O(l) ` `Delta_(r)G^(@) = SigmaDelta_(f)G^(@)(` Products) - `SigmaDelta_(f)G^(@)(`Reactants) `= [ Delta_(f)G^(@) ( CO_(2) +2Delta_(f) G^(@) (H_(2)O)] -[Delta_(f)G^(@) (CH_(3)OH)+(3)/(2)Delta_(f)G^(@) (O_(2))]` `= [( - 394.4) + 2 ( - 237.1) ] - [ - 166.3 + (3)/(2) (0)]` `=- 702 . 3 kJ mol^(-1)` |
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