InorganicChemistry英文PPT (3).ppt

Chapter 2 Thermal chemistry To discuss and calculate the heat change in chemical reactions durations Thermodynamics is the theoretical basis of thermal chemistryHClNaOHDeskSystem:Object of our studyEnvironmentMatter(H2O)Heat flowHeat flowOpen systemClosed systemIsolated system System System openopenclosedclosedisolated isolated Exchange of substanceyesyesnonononoExchange of Energyyesyesnono nonoExampleExample waterwater WaterWaterVaporVapor All of substancesAll of substancesRelationship between system and environment (Substance and Energy)In thermodynamics,we deal mainly with closed systems.Example:System and Environment Adiabatic wallWaterWaterVapor Open system Closed system Isolated system2.1.2 State and State functionThe state of the system:that can be described by state quantitiesThese state quantities:that can describe the physical system with a definite valueTaking the gas as a system:n,p,V,and TWhat determines the state of these systems is defined the state functionState:Thermodynamics the equilibrium state,the comprehensive performance of the physical and chemical properties of the system.The state function is a physical quantity that describes the macroscopic state of a system.such as:n,T,V,pwhich is the physical quantity related to the system state.。The characteristics of state functions:the change of state function is only related to the initial and final states of the system,but has no any relationships with process or pathway.The characteristics of state functions:It is numerical when the state is fixed,the quantity of various substances in the state function should be known.The change of system is demonstrated via the change of state function.The change of state function is only related to the process,but no related to the pathway.So,when the change of state function is calculated,we need to know the initial and final states of the system,the various quantities of substances concerned in state function could be obtained without considering the way of its change.The state functions are related to each other for the same system.(I)Increased pressure(II)Decreased pressure decreased temperatureTwo different processes for an ideal gasDecreased pressuredecreased temperature