Look up the molar enthalpy of combustion H c (T 0 )and Gibbs free energy of combustion G c (T 0 ) for hydrogen under standard conditions Notice that H c (T 0 ) G c (T 0 ) , suggesting that one might be able to extract more than G c from combustion of hydrogen at high temperature, contradicting the ...

Since combustion of H 2 is simply the formation of water we find from Table 98 H c T 0 242 kJmol and ...

Look up the molar enthalpy of combustion H c (T 0 )and Gibbs free energy of combustion

Question:

Look up the molar enthalpy of combustion ΔH_c(T₀)and Gibbs free energy of combustion ΔG_c(T₀) for hydrogen under standard conditions. Notice that |ΔH_c(T₀)| > |ΔG_c(T₀)|, suggesting that one might be able to extract more than |ΔG_c| from combustion of hydrogen at high temperature, contradicting the claim that the energy of a fuel is |ΔG_c(T₀)|. Suppose that the hydrogen is combusted isothermally at temperature Tin an engine that runs at the Carnot limit in an environment at T₀. Assume for simplicity that ΔH_c and ΔS_care independent of temperature. Show that the maximum amount of work that can be extracted from such an engine is in fact W_isothermal(T_M) = |ΔG_c(T₀)| and find the temperature T_M at which the engine must run to reach this limit.