Basic-Gyan

The concept of thermodynamic potentials was introduced by Pierre Duhem in 1886. Josiah  Willard Gibbs in his papers used the term fundamental functions . Thermodynamic potential have the dimensions of energy. Therefore, they are used to measure the energy of a system in terms of various variables because often we can only measure certain properties of the system, not all. For example, we can know the pressure and temperature of the system but not the volume or entropy.    In this article, we will learn about thermodynamic potential / fundamental functions in detail. The thermodynamic potential or fundamental functions allow us to measure more state variables of the system. Thermodynamic Potentials  In thermodynamics, thermodynamic potentials are parameters associated with a thermodynamic system and have the dimensions of energy. Thermodynamic potential/ fundamental functions are  scalar quantities used to represent the thermodynamic state of a system.  ...

We have already discussed the concept of “ Carnot Cycle ”   & “ Its Efficiency ” and we have also seen the concept of “ Carnot Theorem And Its Explanation ” in our previous post. As we have already discussed that the Carnot Cycle is a reversible cycle and every process in the Carnot cycle is a reversible process. Therefore, every process of the Carnot cycle can be reversed. And the cycle can be operated in the opposite direction as well. In this article, we're interested in learning more about the reversed Carnot cycle, also known as the reversed Carnot heat engine cycle. Reversed Carnot Heat Engine It is important to note that if a reversible process is reversed, all related energy types—such as heat energy or work energy—will have the same magnitude but the direction of their interaction with matter will be changed. Let us first look at the Reverse Carnot Heat Engine  cycle here; The reversed Carnot heat engine cycle is depicted in the following figure. According to the...

The difference between internal energy and enthalpy refers to intercepting energy (heat) in different ways.   Internal energy is the heat content of a system, i.e., the sum of all types of specific energies of a system. Whereas, enthalpy is the amount of heat either liberated or engaged in a system. " For a thermodynamic system, When heat is added to a system at constant volume, we use the term internal energy because no work is done and it is a closed system "   &  " When  heat is added to a system at constant pressure then we use the term enthalpy because work is done and it is an open system ".   If q is the amount of heat absorbed by the system from surroundings: Heat (q) at constant volume  =  Internal energy (U) = No work is done  Heat (q) at constant pressure =   Enthalpy (H) = Work is done  FACT :   !!!!We cannot determine the absolute value of internal energy or enthalpy but we can determine the change in internal energ...

When we heat a substance, it starts absorbing heat up to a certain limit, after which, its temperature starts rising. This limit of a substance to tolerate or absorb heat without raising the temperature is termed heat capacity. Therefore, heat capacity is defined as the amount of heat energy required to raise the temperature of a body by 1°C or 1°K. Similarly, when the amount of body/substance is certain (1 kg / unity), the amount of heat energy required to raise the temperature by 1°C or 1°K is termed specific heat capacity. Heat change ∝ Absolute temperature change ➩   [  Q ∝ ∆T ] In this article, we're interested in learning more about the difference between the " Heat Capacity & Specific Heat ".  Generally, heat capacity and specific heat capacity are two proportionality constants that relate to temperature change and the amount of heat. Specific Heat Capacity Vs Heat Capacity Heat capacity is the amount of heat required to raise the temperature of a subst...

Enthalpy (H) of a thermodynamic system is an energy-like state function property that is equal to the total internal energy (U) and pressure-volume (PV) work whereas entropy is an intrinsic disorderness of a system under certain conditions.  In thermodynamics, the change in enthalpy and entropy can be measured rather than their absolute values. In other words, enthalpy is an amount of energy contained in a compound whereas entropy is a measure of disorderness within the compound. History??? In 1909, a Dutch scientist named Heike Kamerlingh Onnes coined the term " Enthalpy .". Total  heat content is  what the word enthalpy denotes. We can determine the amount of heat added to or removed from the system using enthalpy. It is used to measure the heat of a reaction. The term entropy was introduced by the scientist Rudolf Clausius in 1850. The concept of entropy develops from the fact that for energy to be converted to work, some dissipations must occur. This lost energy is ...

The third law of thermodynamics has a controversial past and a number of formulations due to PLANCK , EINSTEIN and NERNST . Between the time period of 1906 to 1912, many formulations of the third law of thermodynamics have been presented by various scientists, but among them all, NERNST'S PRINCIPLE  of un-attainability was the most accepted principle for the third law of thermodynamics. Thus, it is correct to say that this law was developed by the German chemist Walther Nernst between 1906 and 1912.  Let us now look at the various formulations of the third law of thermodynamics proposed by Planck and Nernst. NERNST HEAT THEOREM Walther Nernst was the first to recognize the principle that underlies the third law. The third law of thermodynamics, sometimes called Nernst's theorem or Nernst's Postulate, relates to the entropy and temperature of a physical system.   Walther Nernst’s first formulation of the third law of thermodynamics, called the heat theorem, was th...

When German chemist WALTHER  HERMAAN NERNST  studied about the second law of thermodynamics, his mind was completely disturbed. He studied that the entropy of the universe keeps on increasing for all the processes occurring on its own. He thought that, what should be done so that the entropy of the universe will not increase and it will remain constant? Then he studied everything about entropy. After a lot of studying and research work, he discovered the " Third Law Of Thermodynamics ". In that, he used the concepts of " Absolute Zero Temperature " to limit the value of entropy to a pure perfect crystalline substance. He states the third law as " The entropy of a perfect crystal of a pure substance approaches zero as the temperature approaches zero ".  Generally, entropy increases with increase in system temperature and decreases with decrease in system temperature. At Absolute Zero Temperature (0 Kelvin temperature), all modes of motion stop (no translati...

As we know that thermodynamic deals with the transformation of energy from one form to another and the laws of thermodynamics describe the limits within which these transformations occur.   " The laws of thermodynamics define a set of physical quantities, such as temperature, energy, and entropy, that characterize a thermodynamic system in thermodynamic equilibrium ".   In thermodynamics, we usually study four fundamental laws: the Zeroth Law , the First Law , the Second Law , and the Third Law of thermodynamics.  Zeroth Law, First Law and the Second Law of Thermodynamics lead to the concepts of Temperature , Energy Conservation and The Entropy  respectively. However, the third law does not lead to any new concepts. It only limits the value of the entropy of a pure, crystalline substance when the value of temperature approaches zero.  In this article, we're interested in learning more about the " Third Law Of Thermodynamics ", also known for the concept ...