1.1 Sates of matter

Solid, liquid and gas are three main states of the matter. Solids have definite shape and have highest cohesive or intermolecular forces. These attaraction forces are lesser in magnetudes for liquids. Liquids take the shape of the container and exhibit free surface. Gases have least intermolecular attraction and hence occupy the container completely.

1.2. Laws of thermodynamics

1.2.1 Zeroth law of thermodynamics: This law states that ‘when system A is in thermal equilibrium with system B and system B is separately in thermal equilibrium with system C then system A and C are also in thermal equilibrium’.

This law portrays temperature as a property of the system and gives basis of temperature measurement.

1.2.2 First law of thermodynamics: It states the energy conservation principle, ‘energy can neither be created nor be destroyed but one form of the energy can be converted to other’.

Implimentation of first law for a thermodynamic process defines ‘internal energy’ as a property of the system. According to this law for a closed system, when some amount of heat is supplied to the system, part of it is used to convert into work and rest is stored in the system in the form of internal energy. For the open system, heat supplied splits into enthalpy change and work done by the system.

First law of thermodynamics is thus associated with a corollary which states that there can be no machine (Perpetual Motion Machine of first kind) which can produce continuous work output without having any heat interaction with the surrounding.