Sign convention of heat and work 

1. Heat (q)    Case I:            When heat is absorbed by the system, q = +ve.     Case II:             When heat is released by the system, q = -ve. 2. Work (w)    Case I: (Work of Expansion)             When work is […]

Enthalpy (H) 

It is the sum of internal energy and product of pressure and volume. i.e.          H=E+PV…..(1) Here, E, P & V all are state function so H is also the state function. Being a state function it depends upon initial and final state and also its absolute value cannot be determined however change can be measured. […]

Internal energy (E) 

A compound itself has a definite amount of energy which includes kinetic energy, potential energy, energy of atom, constituting molecules and chemical bond energy. The sum of these different forms of energy (molecules) is called internal energy denoted by E. Internal energy is the state function so, it depends upon initial and final state and […]

First law of thermodynamics 

Ø  Total energy in the universe remains constant. Ø  Energy can neither be created nor be destroyed but can be transferred from one form to another. When Q amount of heat is supplied to the system, some part of it is used up to increase in its internal energy and remaining some part of it […]

Thermodynamic equilibrium 

The system is said to be in thermodynamic equilibrium if it attains thermal, mechanical, and chemical equilibrium at a time with surrounding. Thermal equilibrium means temperature remaining constant. Mechanical equilibrium means pressure remaining constant. Chemical equilibrium means composition/mass remaining constant.

Reversible and Irreversible processes 

Reversible process Irreversible process The process goes through infinite change so, it takes infinite time to complete. The process goes through finite change so, it takes finite time to complete. The process proceeds infinitesimally slowly maintaining the equation state. This process is faster; the equilibrium state is maintained only at initial& final position of system. […]

Thermodynamic Processes 

Isothermal process Any physical or chemical process in which the temperature remains constant during the state change is called isothermal process. Here, ∆T=0 Adbiatic process Any physical or chemical process which takes place without flow of heat in or out of system during the state change is called adbiatic process. Here, ∆Q=0 Isobaric process Any […]

State of a system, state variables and state function 

State of a function (system) is a condition of existence which is described by some of the measureable properties. For e.g.: water exists in three different states i.e. solid, liquid & gas depending upon the temperature at 1atm pressure. The measurable properties of gaseous system are pressure, temperature, volume, mass or composition of substances. Any […]

Introduction to Thermodynamics 

Energy is the capacity of doing work and it has different forms. Energy can neither be created nor be destroyed but can be transferred from one form to another.   Thermodynamics is a branch of science that deals with the inter-conversion of one form of energy into another. In another word, it is the relation […]