(a) Calculate the maximum non-expansion work that can be gained from the combust

Question

(a) Calculate the maximum non-expansion work that can be gained from the combustion of benzene(l) and of H2 (g) on a per gram and a per mole basis under standard conditions. (b) Is it apparent from this calculation why fuel cells based on H2 oxidation are under development for mobile applications?

Explanation / Answer

species       G_formation benzene         124.5kJ/mol CO2             -394.4 kJ/mol H2O               -228.57 kJ/mol H2                        0 O2                        0 2C6H6 + 9O2 => 12CO2 + 6H2O G = (12*-394.4 + 6*-228.57) - (2*124.5 + 9*0) = -6353.22 kJ(per 2 mol benzene) per mol benzene = -3176.61 kJ per mol benzene MW = 78 g/ mol per g benzene = -40.7 kJ/ g benzene 2H2 + O2   =>   2H2O G = 2*-228.57 - (2*0 + 1*0) = -475.14 kJ (per 2 molH2) per mol H2 = -228.57 kJ per mol H2 MW = 2 per g H2 = -228.57 kJ / mol * 1 mol/ 2 g = -114 kJ/g b) So more energy is released per gram for H2 than for benzene.

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