# Topic Category: FIRST LAW OF THERMODYNAMICS

## Problems on First Law of Thermodynamics

Example : 1 The equation of state of a gas is while during an adiabatic process, the gas obeys where a and K are positive constants. All other symbols have their usual meaning. Find the work done by the gas when it is expanded first isothermally from (P, V) to () and then adiabatically from …

## Enthalpy

The enthalpy H of a thermodynamic system is defined as H = U + PV where U, P and V are internal energy, pressure and volume of the systemLet is the heat absorbed in a constant pressure process (First law of thermodynamics) So, A constant pressure is mechanically reversible since if there are unbalanced mechanical …

## Thermodynamic Processes

Isothermal ProcessWhen a thermodynamic system undergoes a process under the condition that its temperature remains constant, then the process is said to be isothermal.Adiabatic ProcessWhen a thermodynamic system undergoes a process under the condition that no heat comes into or goes out of the system then process is said to be adiabatic.Isobaric ProcessWhen a thermodynamic …

## First Law of Thermodynamics

Total energy of any body is given by E = V + K + U Where K is the total kinetic energy which characterises the motion of body. V is the total potential energy of the body which characterises the interaction which the body has with the external field. U is the internal energy of …

## Heat and Internal Work

When two bodies at unequal temperatures are placed in contact, they eventually reach thermal equilibrium at a common intermediate temperature. We say that heat has flowed from the hotter body to colder one.Thermodynamically, the flow of energy from one body to another on account of difference of temperature between them is called heat. Thus, flow …

## Reversible PV Work

Consider a system shown in figure. The system consists of the matter contained within the piston and cylinder walls and has pressure P.Let the external pressure on the frictionless piston is also P. Equal opposing forces act on the piston and it is in mechanical equilibrium. Let x denotes piston location. If the external pressure …

## Thermodynamic Equilibrium

An isolated system is in equilibrium when its macroscopic properties remain constant with time. A nonisolated system is in equilibrium when the following two conditions hold : (a) The system’s macroscopic properties remain constant with time. (b) removal of the system from contact with its surroundings causes no change in the properties of the system. …

## Types of Thermodynamic Systems

The macroscopic part of the universe under study in thermodynamics is called the system. The part of the universe that can interact with the system is called the surrounding.Types of thermodynamic system:(a) Open System : It is system where transfer of energy and matter between system and surrounding can occur.(b) Closed System : A system …