[Obiective]The thermodynamics characters of biodiesel synthesis from rude castor oil(with water and free fatty acid) and methanol were studied.[Method]Yoneda group contribution method and other empirical formulas were applied to calculate the enthalpy,entropy and heat capacity of triglycerides(TG),diacylglycerol(DG),monoglyceride(MG),methyl(ME) and free fatty acids(FFA) of five fatty acids in the system.The thermodynamic analysis of biodiesel synthesis system which involves transesterification,esterificatio...