It is the science of the relations between heat, work and the properties of the systems
In macroscopic approach, certain quantity of matter is considered, without considering the events occurring at the molecular level. These effects can be perceived by human senses or measured by instruments. eg: pressure, temperature. Thermodynamics based on macroscopic approach is called Classical thermodynamics.
In microscopic approach, the effect of molecular motion is considered. eg: At microscopic level the pressure of a gas is not constant, the temperature of a gas is a function of the velocity of molecules. Most microscopic properties cannot be measured with common instruments nor can be perceived by human senses. Thermodynamics based on microscopic approach is called Statistical Thermodynamics
The system is a quantity of matter or a region in space on which we focus our attention (eg: the water kettle or the aircraft engine).
The rest of the universe outside the system close enough to the system to have some perceptible effect on the system is called the surroundings.
The surface which separates the system from the surroundings are called the boundaries as
shown in fig below (eg: walls of the kettle, the housing of the engine).
A system in which, mass and energy (work or heat) can be transferred across the boundary.
A system in which there is no mass transfer but only energy transfer across the boundary.
A system in which there is no mass transfer and energy transfer across the boundary.
It is some characteristic of the system by which the condition of system is described.
Properties whose value depends on the size or extent of the system. If mass is increased, the value of extensive property also increases. eg: volume, mass
Properties whose value is independent of the size or extent of the system. eg: pressure,
temperature (p, T).
A system is said to be in a state when it has definite values for properties. Any operation in
which one or more properties change is called a ‘change of state’.
Class Material: