 myself as Sanjay Murt, Mechanical Engineering Department of Walsh and Institute of Technology in Sallafur. Today I am explaining regarding the next video of this thermodynamics. The learning outcome of this video is student will able to define the properties of thermodynamic systems and pure substance and working substance. The properties of this thermodynamic systems are two types, intensive properties and extensive properties. In the previous video I am explaining regarding the thermodynamics, in that I am related when going to the definition of thermodynamics, you have to check the transaction of heat, work and internal energy of that system related to the different parameters of that system. So related to that there are two type of system I am explaining, system and surroundings. When you have to concentrate the characteristics, when you have to concentrate the properties of that related to that system that is on the defined area that is called as a system and outside that concentrate area or that is called as a surrounding. So when you have to go for the thermodynamic systems, what properties we can study? The properties you can study the pressure, volume, temperature, internal energy, electrical energy, magnetic energy, vibrational energy, rotational energy, some are measurable one and some are non-measurable or negligible ones. So when you have to go for the properties of that system, the properties are two types intensive properties and extensive properties. Intensive properties are those which are independent of that mass, their own properties of the systems of that matter that substance, which are the, they are temperature, pressure, density, viscosity. So these are the intensive properties of that system and when you have to go for extensive properties of that system, they are independent, sorry they are dependent of the mass of that system. They are dependent on the quantity of that system. They are dependent on the quantity of that system that is called as extensive property which are the, these are the volume, mass. So when you have to go for the intensive property of that system, a simple example is a room in that pressure, a room is there and the pressure P is there and if that room is divided into two parts, the pressure remain the same and the room 1 and room 2. Previously whatever the gas in that room is to be there, the pressure P is there, the pressure volume V is there, the temperature T is there, the density rho is to be there. If that room is divided now into two parts, but the values are not changed means they are not related to the mass of that system, they are not related to the quantity of that system. These are called as intensive properties of that system. In the intensive, there is a definite value, it shows that definite value, they are independent mass of that system and they are related to the point functions. So what is a point function, what is a path function that I will explain later on. So these properties are intensive properties, these properties are not related to the mass of that system. They are independent mass of that system and these are temperature, pressure, volume, viscosity. And when you go for the extensive properties of that system, the extensive properties of that system, they are dependent on the size, they are dependent on the mass of that system. It should be noted that the ratio of the two extensive properties they are homogeneous one, heterogeneous one that properties I am explain later on. So, here which are the homogenous system and which are a heterogeneous system. A heterogeneous system in the thermodynamic is defined as whose chemical composition and physical properties are the same in all parts of that system. This means it remains the same which are whose chemical composition and physical properties are the same. You take example of the air whose that chemical composition and physical properties are the same one. On the other hand when I took for the heterogeneous one in the heterogeneous system it consisting of two or more bodies homogenous bodies have to be there. You take example of water that water is mixed with a ice that is a heterogeneous one and the homogenous one it remains the same its chemical composition and physical properties are to be the same one that is a homogenous one and that is a heterogeneous systems are to be there. Now, you go for the definition of the pure substance pure substance when you to go for the study of a thermodynamics whatever the transaction is to be going on that is related to heat and work that transaction of heat and work you have to require some media and that media is called as a substance. So, fixed chemical composition throughout in any phase that is a pure substance means what you take example of water it is a mixture of a two or more substances but it still remain in a pure substance that is a homogenous form that is example of water and ice means you take example that if the phase transformation even take place the water it called as the H2O that is a liquid form ice it is in a solid form again it is called as H2O then what is called as a gas system again it is called as a H2O it is a vapor form again it is a H2O. So, even the phase transformation is to be takes place it remains that chemical composition remains the things it remains to be defined by H2O even the solid phase even in the liquid phase even in the gas phase that is called that is the same it is to be noted by H2O H2O H2O even it is liquid phase gases phase or in a solid phase that is called as a pure substance then you go for a working substance working substance means it is remains in the solid sorry gas or liquid form that is a fluid substance it carries the thermodynamic processes by change in the temperature pressure volume density all these properties they have to carries it is also known as a working fluid why it is called as a working fluid because when heat is added expansion is going on when heat is removed compression is going on contraction is going on when heat is added you get the work of the system you take example of a you need in your house the pump is to be there for the heat pump you have to supply that work when the heat engine is to be there you get the work of that system. So, these are the working media you have to require that is called as a working substance. So, when you know the pure substance when you know the working substance when you know the homogenous system when you know the properties of that system then you give some example for this working substance think over that. So, working substance is that it is this exact state of that matter that substance suppose you go for a graph of pressure versus volume you go for a graph of temperature versus heat supplied that is one state one is to be there that state is a working substance and it denotes its parameters that is a pressure p1 volume v1 temperature t1 that is the exact condition of that system that is called as a state and the condition of the system is described by certain values that is a pressure that values are p1 v1 t1 u1 h1 rho1. So, it defines at the minimum two properties of that system it defines then it knows its characteristic of that system exact position of that system that is a working substance that is a refrigerant coolant working gas steam in the steam engine. So, when the number of changes occur in the succession then the complete series that is called as a path means the working substance moves from one equilibrium stage to the other equilibrium stage from state one to the state two from the state two to the state three when the state one is to be there that working substance having minimum two parameter you can know it if a pressure versus what you call volume graph is to be there p1 v1 you can note down it then it moves from state one to the state two from one stage to the another state from state one it is an equilibrium condition when you go for a state two equilibrium condition some transaction is going on from state one to the state two it is a p2 and p2. So, this is the definitions of the working substance pure substance ok. Thank you for that the basic references used for this that is the basic books used that is the basic mechanical engineering by R.S. Gurmey.