Change in enthalpy and change in internal energy are state functions. The value of DeltaH, DeltaU can be determined by using Kirchoff's equation. Calculate the heat of formation of methane, given that heat of formation of water = -286kJ mol^(-1), heat of combustion of methane = -890kJ mol^(-1) heat of combustion of carbon = -393.5 kJ mol^(-1)

Change in enthalpy and change in internal energy are state functions.

1.	Change in enthalpy and change in internal energy are state functions. The value of DeltaH, DeltaU can be determined by using Kirchoff's equation. Calculate the heat of formation of methane, given that heat of formation of water = -286kJ mol^(-1), heat of combustion of methane = -890kJ mol^(-1) heat of combustion of carbon = -393.5 kJ mol^(-1)
Answer» `90.5 kJ mol^(-1)` `-240 kJ mol^(-1)` `-75.5 kJ mol^(-1)` `95.6 kJ mol^(-1)` Solution :`CH_(4) + 2O_(2) rarr CO_(2) + 2H_(2)O` `DELTA H = Delta H_(f_(CO_(2))) + 2DELTA H_(f_(H_(2)O)) - Delta H_(f_(CH_(4)))` `Delta H_("COMBUSTION"_(CH_(4))) = Delta H_("combustion"_(( C))) + 2 Delta H_(f_(H_(2)O)) - Delta H_(f_(CH_(4)))` `-890 = -393.5 + 2 XX (-286) - Delta H_(f_(CH_(4)))` `Delta H_(f_(CH_(4))) = - 75.5` kJ/mol