热力学第一定律 盖斯定律( Hess law) The standard enthalpy of an overall reaction is the sum of the standard enthalpies of the individual reactions into which the overall reaction may be divided -Individual steps may not be"real" reactions, but must balance △/kJmo C3H6(g)+H2(g) C3Ha(g) 124 C3H8(g)+502(g)3CO2(g)+4H2O() 2220 H2O() H2(g)+O2(g) +286 C3H6(g)+(9/2)O2(g) 3cO2(g)+3H2O() 2058盖斯定律 (Hess’ Law) 热力学第一定律