Thermodynamics
The changes take place in our surroundings. The point is how this system is changed and what are the factors which cause this change and affect the surroundings.
Thermodynamics is about how our system changes with the
changes in the environment. And which factors are involved in this change and
how they affect the surroundings.
Table to content:
Introduction
A brief discussion on thermodynamics
Branches of thermodynamics
Basic terms related to thermodynamics
Interactions of thermodynamics systems
Thermodynamics properties
Thermodynamics potential
Thermodynamics process
Thermodynamics laws
What is thermodynamics?
Thermodynamics deals with heat, temperature, energy, and
work. It is about how energy changes from one form to another and work is done.
How does the system change? How change takes place in the surrounding?
Thermodynamics is about how thermal energy changes from one
form to another and system is affected and work is done. Heat (produces due to
motion of particles) transfers due to which temperature changes (due to the transfer
of heat) energy is produced and work is performed by that.
Thermodynamics is a macroscopic property of material it does
deal with how matter is constituting but with the system and its surroundings.
what is a system and how it is affected by its surrounding? First, we need to
know about the system and surroundings.
Branches of thermodynamics:
On different experiment and theoretical bases,
thermodynamics is divvied among four branches
Classical thermodynamics
Statistical thermodynamics
Chemical thermodynamics
Equilibrium thermodynamics
Classical thermodynamics:
It was developed by
19 century to describe the state of the system on large. By the uses of macroscopic
and measurable properties, classical thermodynamics describes the state of
thermodynamics at near equilibrium. It is used to model the exchanges of energy,
work, and heat based on the law of thermodynamics.
Statistical thermodynamics:
In the early 20 century, with the development of atomic and
molecular theories, it emerges with a description of microscopic interaction
between individual particles (quantum mechanical state). The microscopic
description of classical thermodynamics is given by statically mechanics. It relates
the microscopic properties of an individual atom to the macroscopic properties
of the material.
Chemical thermodynamics:
chemical thermodynamics deals with
how energy and work interrelate during the chemical reaction in the physical
state without violation of the laws of thermodynamics.
Equilibrium thermodynamics:
Thermodynamics Equilibrium
deals with the transformation of heat and energy from one system to another or
surroundings to achieve equilibrium. Thermodynamics Equilibrium indicates such a
state of equilibrium where there are no
unbalanced forces, no unbalanced potential
no macroscopic flow of matter and energy
intensive properties (temperature, density, etc.) are
homogenous
and pressure is perpendicular to the boundaries of the
system
The aim or goal of thermodynamics equilibrium is to
calculate a final aquarium state of the system by giving an initial equilibrium
state to its system and its surroundings.
Non-Equilibrium thermodynamics:
Non- Equilibrium thermodynamics deals with a system that is
not at equilibrium. Most of the systems in our surroundings are not in
equilibrium because matter and energy are continuously transforming from one
system to another or surroundings.so, there is much need to study the system
and surroundings at a non-equilibrium state
What is the difference between the system and surroundings?
System:
Any region which is under study is called a system. It can
also be said that any region that constitutes matter or volume is called a system.
It could be anything, it can be small as an atom and can be as large as a black
hole. It could be solid, liquid and gas. The state and movement of its particles
describe its properties such as internal energy.
For Example:
A cylinder enclosed a molecule of gas, the molecules inside
a cylinder constitute a system.
Surroundings:
Anything in the
universe except the system is called surroundings. It interacts with the system.
The processes which take place in the environment surround the system and affect
its functioning.
For Example
A cylinder enclosed a molecule of gases, then the
environment which surrounds the cylinder is called surroundings
Boundary:
The wall between the system and surroundings is called a boundary
that separates the system from the surrounding. The transfer of energy, heat,
matter, and energy between the system and surroundings takes place through the boundary.
For example:
A cylinder enclosed a molecule of gas, then the cylinder
itself is called boundary because it separates molecules of gas from the environment.
Types of Boundaries:
·
fixed
·
Moveable
·
Real
·
Imaginary
There are four types of boundaries:
Fixed boundaries: The boundaries which are fixed (means unable to move or position is fixed) by applying force between system and surrounding is called fixed. For example, the cylinder enclosed the molecules of gases, then the cylinder (the boundary) is called fixed because it is unable to move by applying force, pressure, etc.
Moveable boundaries: The boundaries which can be moveable (means easily sliceable) by applying force are called moveable boundaries. For Example, if the cylinder is enclosed by a moveable piston then the boundary is moveable while the cylinder boundary is fixed.
Real boundaries: The boundaries which are real can be
seen with real eyes are called real boundaries. For Example, the glass
containing water, cylinder enclosed a molecule of gases than the glass and cylinder
its form a real boundary.
Imaginary boundaries: The boundaries which are assumed as imaginary are called imaginary boundaries. For Example, the glass containing water then, the imaginary boundary on the surface of the water is assumed as an imaginary boundary.
Interactions of thermodynamics systems:
A thermodynamics system is a portion of matter surrounded by
a boundary. The mass, energy, and matter are transformed by the boundary
between the system and surroundings. Some system does not allow the transformer
of some energies to transfer through their boundaries.
Types of the system:
Open system: In an open system, the mass and the energy can
be transferred between the system and its surroundings. e.g., a steam turbine is an example of an
open system
Closed system: In closed system energy can be
transferred but matter cannot be transferred across the boundary. e.g., The
compression of gas molecules in piston-cylinder is an example of a closed
system
Isolated system: A system that cannot transfer both energy and matter between the system and surroundings is called an isolated system. e.g., our universe is considered as an example of an isolated system.
|
Types of
system |
work |
heat |
Mass flow |
|
Open |
yes |
yes |
yes |
|
Closed |
yes |
yes |
no |
|
Thermally
isolated |
yes |
no |
no |
|
Mechanically
isolated |
no |
yes |
no |
|
Isolated |
no |
no |
no |
What are thermodynamics properties? The difference is the
intensive and extensive properties?
There are two properties of thermodynamics, these are
Intensive property
Extensive property
Intensive property:
The property does not depend upon the size of the system and
matters within the system. For example the temperature, density, and refractive
index.
Extensive property:
The property of the system depends upon the size of the system
and matter within the system. For example volume, mass and entropy.
What is enthalpy?
Entropy is the
property of the thermodynamics system. It is a state function. The enthalpy of the
system is equal to the sum of internal energies and the product of pressure and
volume. It is designated by H. It has the dimensions of energy which is the joule.
H =
U + PV
What is entropy?
It is the property of thermodynamics. It is also a state
function. Entropy is defined as a measure of the disorder of a system.
It is a physical property associated with uncertainty, randomness. It is designated by s. Its unit is cal/
Kmol.
Heat:
In thermodynamics, heat is energy, transfer from one system
to another or surrounding. heat can also flow from a higher temperature system
to a lower temperature system. Heat is typically measured in calories, Btu, or
joules.
Thermodynamics potential :
Thermodynamics potential is a measure of stored energy in a
system. Potentials are the measure of the change of energy in a system from the
initial state to the final state.
The different thermodynamics potentials are:
Enthalpy
Internal energy
Landau potential or grand potential
Gibbs free energy
Helmholtz free energy
Other Thermodynamics
potentials can be derived from the Legendre transformation.
State and equilibrium:
The state is the condition of the system. In-state all the
properties of the system have fixed values. If the value of one property
changes, the state of the system changes. If the system is in equilibrium, then
there is no change in the value of properties.
There are some equilibrium states where some thermodynamics
properties are constant.
Thermal equilibrium: when there is no change in the temperature of the system, then the system is on thermal equilibrium.
Phase equilibrium: when the mass of two-phase reaches equilibrium, then the system is on phase equilibrium.
Mechanical equilibrium: when the pressure of the system remains constant, then the system is on mechanical equilibrium.
Chemical equilibrium: when the chemical composition of the system does not change, then the is on chemical equilibrium.
The thermodynamics process is the process that proceeds from
the initial state to the final state. There are several ways or paths to proceeded
the system from the initial state to another. The paths are those where the
different conditions are provided to the system such as constant temperature,
pressure, and volume, etc.
There are different thermodynamics process
Adiabatic process
Isothermal process
Isobaric process
Isochoric process
Isentropic process
Isenthalpic process
Steady-state process
The description of some thermodynamics processes are as
follows:
Adiabatic
process:
The
thermodynamics process is in which there is no transfer of heat from the system
to the surroundings. They could be only possible when there is rapid action
taken place. For example, when the compression of gas occurs in the cylinder,
it is assumed to occur at a faster rate than no heat transfer can occur.
Isothermal
process:
The
thermodynamics process in which the temperature of the system remains constant.
In this process, the changes take place so slowly to allow the system to
transfer energy and keep the temperature remains constant. For example, phase
changes such as vaporization, melting, icing are examples of the isothermal
process.
Isobaric
process:
The
thermodynamics process in which the pressure of the system remains constant.
Although the heat can be transferred, work can also do. In this way, the
internal energy of the system changes but pressure remains constant. For example,
the reversible expansion of an ideal gas can be considered as the example of the
isobaric process in which heat is transferred to do work when expansion takes
place.
Isochoric process:
The isochoric
process is also known as a constant- volume, and isovolumetric process or an
isometric process. The thermodynamics process in which the volume of the closed
system (undergoing process) remains constant. The quasi-static process is an
example of the isochoric process.
Isentropic process:
The
thermodynamics process is in which the entropy of the system is constant. This
can adiabatic and reversible because the heat transfer is zero. For example,
the pumps, diffusers the nozzles are going through an isentropic process.
Isenthalpic
process:
The
thermodynamics process on which the enthalpy of the system remains constant the
throttling process is an example of the isenthalpic process.
Steady-state
process:
The
thermodynamics process is in which the internal energy of the system remains
constant. This process has vast applications in every field such as mechanical engineering,
chemical engineering, electrical, electronics, physiology, fiber optics, economics,
etc.
What are the
laws of thermodynamics? When are the laws of thermodynamics is valid?
The laws of
thermodynamics deal with physical quantities such as temperature, thermodynamics,
etc. it also discusses the behavior of these quantities under different circumstances.
These laws of thermodynamics are valid only when the system is in thermal
equilibrium. These laws are not valid when the system goes through a complicated
transition state and rapid change.
How many
laws of thermodynamics? What are the laws of thermodynamics and briefly
describe them?
There are
four laws of thermodynamics
The first
law of thermodynamics
The second
law of thermodynamics
Third law of
thermodynamics
Zeroth law
of thermodynamics
The
description of these laws are as follow:
The first
law of thermodynamics:
Can
energy be destroyed or lost?
The first
law of thermodynamics states:
“ Energy can neither be
created nor be destroyed but can be transformed from one form to another.”
Examples of the first law of thermodynamics:
Human
metabolism is the best example of the first law of thermodynamics. It is the conversion
of food to transfer heat and work is done.
The plant
takes light for the sun and converts into food by photosynthesis, then human
eats plants, take energy from them which then breakdown by process of
metabolism and human uses this energy to different works.
In the
process, in which matter doesn’t transfer, the change in internal energy of the
system is equal to gained in heat, less the thermodynamics work, done by the system
on its surroundings.
In the
process, in which matter transfers. When the two systems with internal energies
u1 and u2 can be different in composition, separated by an impermeable wall
when the wall is removed the internal energy of system u0 is equal to the sum
of internal energies u1 and u2.
The first
law of thermodynamics is also called the law of conservation of energy.
The second law of thermodynamics:
The second
law of thermodynamics states:
“
Heat transfer occurs spontaneously from higher to lower body temperature
bodies.”
The entropy
of an isolated system always increases. Entropy is the measure of how much the
process has progressed.
Third law of thermodynamics:
The third
law of thermodynamics states that:
“As the temperature of
a system reaches absolute zero, then the entropy of a system approaches almost
zero.”
The entropy
of all the states of the system is almost zero, the absolute temperature (
-273k ) is impossible to reach. This law provides the reference point for the
determination of entropy.
Zeroth law of thermodynamics:
The zeroth law of thermodynamics states:
“If two systems are in
thermal equilibrium with third one, then two bodies are also in thermal
equilibrium with each other.”
The zeroth
law was not initially considered a separate law of thermodynamics as its basis
was implied in the other laws.
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