3. Introduction
• Thermodynamics, science of the relationship between
heat, work, temperature, and energy. In broad terms,
thermodynamics deals with the transfer of energy from
one place to another and from one form to another. The
key concept is that heat is a form of energy
corresponding to a definite amount of mechanical work.
5. Different branches of thermodynamics
• Classical Thermodynamics
• In classical thermodynamics, the behaviour of matter is analysed with
a macroscopic approach. Units such as temperature and pressure are
taken into consideration, which helps the individuals calculate other
properties and predict the characteristics of the matter undergoing the
process.
6. • Statistical Thermodynamics:-
• In statistical thermodynamics, every molecule is under the spotlight,
i.e. The properties of every molecule and how they interact are taken
into consideration to characterise the behaviour of a group of
molecules.
• Chemical Thermodynamics:-
• Chemical thermodynamics is the study of how work and heat relate to
each other in chemical reactions and in changes of states.
8. Laws of thermodynamics
• There are four laws of thermodynamics and are given below:
1. Zeroth law of thermodynamics
2. First law of thermodynamics
3. Second law of thermodynamics(not in syllabus)
4. Third law of thermodynamics ( not in syllabus)
9. Zeroth law of thermodynamics
• The Zeroth law of thermodynamics states that if two bodies are
individually in equilibrium with a separate third body, then the first
two bodies are also in thermal equilibrium with each other.
• Concept:-This means that if system A is in thermal equilibrium with
system C and system B is also in equilibrium with system C, then
system A and B are also in thermal equilibrium.
11. Diagram representation
• 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 reads 100 °C,
we say that the thermometer is in equilibrium with cup A. 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. By 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.
12. First law of thermodynamics
• First law of thermodynamics, also known as the law of conservation
of energy, states that energy can neither be created nor destroyed, but
it can be changed from one form to another.
• Concept The first law of thermodynamics may seem abstract, but we
will get a clearer idea if we look at a few examples of the first law of
thermodynamics.
14. • According to this law, some heat given to the system is used to change
the internal energy while the rest is used in doing work by the system.
• It can be represented mathematicaly as:-
15. • In this equation:-
•
• ΔQ is the heat given or lost
• ΔU is the change in internal energy
• W is the work done.
16. EXAMPLES :-
• First Law Of Thermodynamics Examples:
• 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 scroll through this page.
• Switching on light may seem to produce energy, but it is electrical energy that
is converted.
17. Application for first law of thermodynamics
• Cyclic process:-
The process in which the initial and final states are the same is known as
a cyclic process.
• Isolated system:-
• A thermodynamic system that cannot exchange either energy or
matter outside the boundaries of the system.
18. • Isobaric process:-
A process occurring at constant pressure
• Isochoric process:-
The volume of the gas remains constant
• Isothermal process
An isothermal process is a thermodynamic process in which the
temperature of a system remains constant.
19. • Second law of thermodynamics:
. The entropy of any isolated system always increases.
• Third law of thermodynamics:
The entropy of a system approaches a constant value as the t
temperature approaches absolute zero.
20. Equivalance of work and heat
• Joule’s mechanical equivalent of heat is the amount of work required
to produce 1 calorie of heat. According to the first law of
thermodynamics, the change in internal energy associated with a
system is equal to the sum of work done by the system and heat added
to the system
1 kilocalorie = 4.18 *10³
1 calorie = 4.18 joule
W=JQ
21. Sign Convention for Heat:-
• When heat is given from a system to Its surrounding,then
heat is taken with negative sign.(-ve)
• Whwn heat is taken from its surroundings by the
system,then heat is taken with positive sign.(+ve)
22. Thermodynamics Examples in daily life:-
• Whether we are sitting in an air-conditioned room or travelling in any
vehicle, the application of thermodynamics is everywhere. We have
listed a few of these applications below
• The three modes of heat transfer work on the basis of
thermodynamics. The heat transfer concepts are widely used in
radiators, heaters and coolers.
• Thermodynamics is involved in the study of different types of power
plants such as nuclear power plants, thermal power plants.
23. Conclusion
• The first law of thermodynamics states that energy
can either be created or destroyed, only altered in a
form. In analyzing an open system using the first law
of thermodynamics, the energy into the system is
equal to the energy leaving the system.
