// Given:- // Methane is formed from carbon and hydrogen according to // C + 2H2 ----- CH4 // In the present case, all substances are at the same temperature and pressure, 25C and 1 atm, which correspond to the standard reference state values hCbar = 0 hH2bar = 0 gRbar = 0 // With enthalpy of formation and absolute entropy data from Table A-25 hfbarCH4 = -74850 sbarCH4 = 186.16 sbarC = 5.74 sbarH2 = 130.57 Tref = 298.15 // in kelvin // Calculation gfbarCH4 = hfbarCH4 -Tref*(sbarCH4-sbarC-2*sbarH2) // in kj/kmol // Result printf( ' The gibbs function of formation of methane at the standard state is: %f kJ/mol',gfbarCH4)