Thermodynamics

Thermodynamics Science of energy transfer, heat and work by changing the property of the system. - Convert disorganized form of energy in to organized form. system: Region in space upon which study is concentrated. surrounding: Anything which is outside the system. Boundary: Separation between system and surrounding.

System and types of system Mass transfer Energy transfer Examples Closed x √ Piston cylinder without valves Open Turbine ,compressor ,pump Isolated

Microscopic and macroscopic approach Microscopic approach: Behavior of individual molecule is considered. Statistical thermodynamics, study at low density. Macroscopic approach: not study the behavior of individual molecules but average molecular behavior taken in to consideration.(classical thermodynamics)

Substance Pure substance: A substance is said tobe pure substance if it is homogeneous in chemical composition and in chemical bonding. Solid-metal Liquid-water Gas-air, oxygen, hydrogen

P-T diagram for pure substance

Liquid-vapour terms Saturation temperature Saturation pressure Saturated liquid Saturated vapor Dry (saturated) vapor Wet vapour Superheated vapour

Properties of the system Intensive(intrinsic) properties: Independent of size or mass of the system. i.e.: pressure,temprature,themal conductivity, viscosity Extensive(extrinsic) properties: depends on size or mass of the system. i.e. volume,mass,area, all forms of energy. Note: ratio of two extensive properties is a intensive property mass/volume= density.

Specific properties are intensive properties represents in unit mass form. i.e. specific volume, specific heat Important points regarding properties: Properties are point function or state function. Properties are independent of past history. Properties are exact differentials.

State of a system Condition of a system represents in terms of properties known as state. As long as properties of the system is fixed state is also fixed. Process: change of a state is known as process.

GIBB’s phase rule P+ F =C+2 P=no. of phase F=degree of freedom C= no. of components.

Thermodynamic cycle A system is said to undergone cycle if initial and final stage is same. A system is said to be reversible as it follows the same path as that of the forward path and does not leave any effect on system and surrounding. A process which is not reversible process is irreversible process. Friction is one of the reason that makes process irreversible. Reversible process is most efficient process.

Quasi static process -Carried out in very slew manner with small gradient. Point function: When two properties locate a point on the graph(co-ordinate axes) then those properties are called as point function. Examples. Pressure, temperature, volume etc. Path function: There are certain quantities which cannot be located on a graph by a point but are given by the area or so, on that graph. In that case, the area on the graph, pertaining to the particular process, is a function of the path of the process. Such quantities are called path functions. Examples. Heat, work etc.

Zeroth law If body ‘A’ is in thermal equilibrium with body ‘B’ and body ‘B’ is in thermal equilibrium with body ‘C’ than ‘A’ and ‘C’ will be in thermal equilibrium.