2.1.2 State and state function State:the comprehensive condition of a system. State function:physical quantities depicting the property of a system.(e.g.,p,V,T;M...) The characteristics of a state function: (1)the value of a state function is unique when the state of a system is specified. 2.1.2 State and state function State：the comprehensive condition of a system. State function：physical quantities depicting the property of a system. (e.g., p,V,T,M… ) The characteristics of a state function: (1) the value of a state function is unique when the state of a system is specified