上游充通大￥ SHANGHAI JIAO TONG UNIVERSITY 7.1 Thermodynamic activity Fugacity is defined for gases: dG;=RTd(In fi) Energetic,in terms of energy or chemical potential Thermodynamic activity of a component,i,is defined as: C;≡ The fugacity of the component iin its standard state. The fugacity of a condensed phase is equal to the fugacity of the vapor phase in equilibrium with it. The fugacity of the vapor is equal to the pressure of the vapor,if the vapor in equilibrium with the condensed phase is ideal7.1 Thermodynamic activity Energetic, in terms of energy or chemical potential