Introduction:
In Physics, thermodynamics deals with temperature,
heat and their relation to energy, radiation, work, and properties of matter.
The energy can be of many forms such as electrical, mechanical, or chemical
energy. William Thomson coined the term thermodynamics in 1749. It is derived
from two Greek words “thermos” meaning heat, and “dynamics” meaning powerful.
When we say the word dynamic we think of motion or
movement and energy. Thus, the term thermodynamics means heat movement or heat
flow.
What is Thermodynamics?
Thermodynamics
is the branch of Physics which is concerned with the relationship between other
forms of energy and heat. We can define thermodynamics as:
- · The branch of physics that deals with heat and temperature, and their relation to energy, work, radiation, and properties of matter.
To be specific, it explains how thermal energy is converted to or from other forms of energy and how
matter is affected by this process. Thermal energy is the energy that comes
from heat. This heat is generated by the movement of tiny particles within an
object. The faster these particles move, the more heat is generated.
What
is the thermodynamic process?
A thermodynamic process is a passage of a thermodynamic system from an initial to
a final state of thermodynamic equilibrium.
Thermodynamics Timeline
Thermodynamics
has many sections under it and is considered as a broad subject because it
deals with topics that exist all around us and thus classification becomes
necessary.
- Classical
Thermodynamics:
In
this section, the behaviour of matter is analyzed with a macroscopic approach.
Units such as temperature and pressure are taken into consideration which helps
the individuals to calculate other properties and to predict the
characteristics of the matter that is undergoing the process.
- Statistical
Thermodynamics:
In
this section, every molecule is under the spotlight i.e. the properties of each
and every molecule and ways in which they interact are taken into consideration
to characterize the behaviour of a group of molecules.
- Pure
Component Thermodynamics:
As
the name itself states this section tries to describe the behaviour of a system that has an unadulterated or pure constituent.
- Solution
Thermodynamics:
This section attempts to describe the behaviour of a system that contains more than
one chemical in the mixture.
What
are Laws of Thermodynamics?
The
laws of thermodynamics define the fundamental physical quantities like energy,
temperature and entropy that characterise thermodynamic systems at thermal
equilibrium. The laws represent how these quantities behave under various
circumstances.
How many laws of thermodynamics
are there?
There
are four laws of thermodynamics and are given below:
- Zeroth
law of thermodynamics
- First
law of thermodynamics
- Second
law of thermodynamics
- Third
law of thermodynamics
Zeroth Law of Thermodynamics
The
Zeroth Law is the basis for the measurement of temperature. It states that:
Two bodies which are in thermal
equilibrium with a third body are in thermal equilibrium with each other.
Zeroth
Law Of Thermodynamics Examples:
consider
two cups A and B with boiling water.
When
a thermometer is placed in cup A, it gets warmed up by the water
until it reads 100°C.
When
it read 100°C, we say that the thermometer is in equilibrium with cup A.
Now
when we move the thermometer to cup B to read the temperature,
it continues to read 100°C.
The
thermometer is also in equilibrium with cup B.
From
keeping in mind the zeroth law of thermodynamics, we can conclude that cup A and cup B are in equilibrium with
each other.
The
zeroth law of thermodynamics enables us to use thermometers to compare the
temperature of any two objects that we like.
First
Law of Thermodynamics
The
first law of thermodynamics which is also known as the conservation of energy
principle states that:
Energy can neither be created nor
destroyed, but it can be changed from one form to another.
This
law may seem abstract but if we look at a few examples of the first law of
thermodynamics, we will get a clearer idea.
First
Law Of Thermodynamics Examples:
Fans
convert electrical energy to mechanical energy.
Plants
convert the radiant energy of sunlight to chemical
energy through photosynthesis. We eat plants and convert the
chemical energy into kinetic energy while we swim, walk, breathe and when we
scroll through this page.
Second Law of Thermodynamics
The
second law of thermodynamics states that:
Energy in the form of heat only flows
from regions of higher temperature to that of lower temperature.
Many
individuals take this statement lightly and for granted, but it has an
extensive impact and consequence. This is why it costs money to run an air
conditioner. The human body obeys the second law of thermodynamics too.
Second
Law Of Thermodynamics Examples
One
of the examples of the second law of thermodynamics can be sweating in a
crowded room. Assume yourself to be in a small room full of people. You are
very likely to feel warm and start sweating. Sweating is a mechanism the human
body uses to cool itself. Here, the heat from your body is transferred to
sweat. As the sweat absorbs more and more heat from the body it evaporates and
transfers heat to the surrounding air, thereby, heating up the temperature of
the room.
Third
Law of Thermodynamics
The
Third Law states that:
The entropy of a perfect crystal is
zero when the temperature of the crystal is equal to absolute zero (0 K)
Entropy
is sometimes called “waste energy” i.e., the energy that is
unable to do work, and since there is no heat energy whatsoever
at absolute zero, there can be no waste energy.
Third
Law Of Thermodynamics Examples:
Let
us consider steam as an example to illustrate the third law of thermodynamics
step by step:
We
know that steam is a gaseous state of water at higher temperatures. In this
state:
The
molecules within it move freely and have high entropy.
If
one decreases the temperature below 100°C, the steam gets converted to water,
where the movement of molecules is restricted, decreasing the entropy of water.
When
water is further cooled below 0°C, it gets converted to solid ice. In this
state, the movement of molecules is further restricted and the entropy of the
system reduces more.
As
the temperature of the ice further reduces, the movement of the molecules in
them are restricted further and the entropy of the substance goes on
decreasing.
When
the ice is cooled to absolute zero, ideally the entropy should be zero. But in
reality, it is impossible to cool any substance to zero.
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