2013-2-27 STATE AND EQUILIBRIUM ynmic ea with Fauilibrium A state of balance In an equilibrium state there are no m2kg T1=209 =15 w. The Mechanical eauilibrium:If there is n at any point ofh 20C 23℃ 32 32℃ d when the 30 32 involves two ph is c level and stays there Acosed system reacn mica (a)Before (b)After change with tim thermal equilibrium. 3.11 The State Postulate The number of properties required to fix the state of a system is given by the state postulate: The state of a simple compressible system is Nitrogen T=25C properties. V=0.9 m/kg Simple compressibles syste a system involves no electrical. State of nitrogen is magnetic,gravitational,motion. and surface tension effects.(the fixed by two independent, only energy transfer by work is by volume change). intensive properties 3.12 6 2013-2-27 6 A closed system reaching thermal equilibrium. 3-11 STATE AND EQUILIBRIUM Thermodynamics deals with equilibrium states. Equilibrium: A state of balance. In an equilibrium state there are no unbalanced potentials (or driving forces) within the system. Thermal equilibrium: If the temperature is the same throughout the entire system. Mechanical equilibrium: If there is no change in pressure at any point of the system with time. Phase equilibrium: If a system involves two phases and when the mass of each phase reaches an equilibrium level and stays there. Chemical equilibrium: If the chemical composition of a system does not change with time, that is, no chemical reactions occur. A system at two different states. The State Postulate The number of properties required to fix the state of a system is given by the state postulate: The state of a simple compressible system is completely specified by two independent, intensive properties. Simple compressible system: If a system involves no electrical, magnetic, gravitational, motion, and surface tension effects.(the only energy transfer by work is by volume change). 3-12 State of nitrogen is fixed by two independent, intensive properties