Thermodynamics Equations

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Thermodynamics Equations
Thermodynamics Equations
Thermodynamics is expressed by a mathematical framework of thermodynamic equations
which relate various thermodynamic quantities and physical properties measured in a
laboratory or production process.
Thermodynamics is based on a fundamental set of postulates, that became the laws of
One of the fundamental thermodynamic equations is the description of thermodynamic work in
analogy to mechanical work, or weight lifted through an elevation against gravity, as defined in
1824 by French physicist Sadi Carnot.
Carnot used the phrase motive power for work. In the footnotes to his famous On the Motive
Power of Fire, he states: "We use here the expression motive power to express the useful
effect that a motor is capable of producing. This effect can always be likened to the elevation
of a weight to a certain height.
It has, as we know, as a measure, the product of the weight multiplied by the height to which it
is raised." With the inclusion of a unit of time in Carnot's definition, one arrives at the modern
definition for power:
Know More About :- Specific Heat Formula
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Thermodynamics is sometimes called energetics. Thermodynamics is based on three
fundamental laws. They are applicable to all the phenomena in nature. These laws are not
based on any theory but are based on experimental facts.
The laws have been subjected to rigorous mathematical treatment and have yielded
correlations between different observable properties of matter. These have been proved to be
very convenient and useful in describing the states of system in chemical and physical
The result of thermodynamic deductions have been proved to be correct by experiments and
found to be rigidly valid. Thermodynamics is, therefore an exact science.Thermodynamics has
a great predicting power.
It can predict whether a given process will occur spontaneously or not under a given set of
conditions. The laws provide necessary criteria for predicting the feasibility of a process.
However, it gives no information with regard to the rate at which a given change will proceed.
Thermodynamics deals only with the states of the system and makes no mention of the
mechanism of how the change is accomplished.Thermodynamics answers why a change
occurs but not how it occurs.
Classical thermodynamics is based on the behavior of bulk or macroscopic properties of the
system, i.e., systems having many molecules and is independent of the atomic and molecular
Consequently, no information can be obtained regarding the molecular structure. This difficulty
is however obviated in statistical thermodynamics where the laws of mechanics are applied to
the behavior of individual molecules and then a suitable average is taken.
The results obtained from classical and statistical thermodynamics are however
complementary to each other.
Learn More :- Enthalpy of Formation
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History of Thermodynamics :- From the time of stone age humans knew about the
Thermodynamics. The knowledge of friction of dry wood with one another producing fire,
cooling of air when air is blown through a small opening in lips and cooling of the surroundings
when hail stones melt to become water and burning of some inflammable material resulting in
release of heat are some of the earlier observations related to thermodynamics.
1. The first idea of thermodynamics was established by Fourier, Kelvin, Gibbs, and Carnot
amongst others.
2. Thermodynamics began in 1822 with Fourier's publication of the theorie analytique wherein
it is derived that the partial differential equation for the temperature distribution in a rigid body.
3. Sadi Carnot a couple of years later put down further the foundations of thermodynamics
with his renowned memoir about steam power. He perceived that steam power was a motor of
industrial revolution that would prompt economical and social life.
4. The caloric, a notion introduced by Lavoisier was to identify heat was further worked upon
by James P Joule who identified it as a form of energy transferring by showing experimental y
that heat and work are mutually convertible.
5. This was the birth of concept of energy and the basis of formulation of the first law of
Fundamentals of Thermodynamics:- Matter tends to be at rest. To attain this state
substances change their state so that they can be with minimum internal energy. In this
process the excess energy is given as heat. Some times the substances which are with
minimum internal energy get activated by supply of energy in the form of heat.
The study of these energy changes is the fundamental feature of Thermodynamics.
Thermodynamics is not based on hypothetical laws but is experimentally determined.
Generally, the values are taken at 1 atmosphere pressure and room temperature taken as
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