Some of the applicaitons of some phenomens in Physics

1. Applications of
Enthalpy
Enthalpy is the amount of heat used or
released in a system at constant pressure.
The standard SI unit for enthalpy is joules,
and it is represented by ΔH.

2. The Process

3. • It is used to
• calculate the heat of reaction of a chemical
process
• to measure heat flow in calorimetry
• to calculate minimum power for a compressor.
• In a fridge, freon is evaporated. The amount of
Freon evaporated is directly related to the
coldness of your food in the fridge.

4. • A car engine produces heat by
burning fuel. The energy is
produced as soon as fuel burns.
This is another real-life application
of enthalpy change.

5. • It can also be applied to sever every day factors, such as the
engine in your car which turns the heat of combustion of the
fuel, through several steps, into the energy which is translated to
the movement of the car. This can be applied industrially as the
engineers creating the cars can use it to determine if new fuels
would heat the engine more or less and how they would affect
the ability of movement and speed of the car.

7. Gibbs Energy

8. Gibb's energy is
useful because it
relates properties of
a system with the
entropy change of
the universe.
ΔG=ΔH−TΔS

9. A Simple Explanation
• Remember the energy that is
required to complete a reaction when
there was not enough energy for the
process.

10. Diamond into Graphite

11. Helmholtz Energy
U S U AL LY F O R E X P L O S I V E
R E AC T I O N S
This Photo by Unknown author is licensed under CC BY.

12. In Auto-encoder
• artificial neural network that is
used to efficiently encode data.
Helmholtz energy is utilized to
calculate the total coding cost
and reconstructed code in this
case.

13. Eq. Of State of Pure
Liquids with Precision
• . For a small number of
important substances,
reference equations have been
developed that are capable of
representing the best
experimental physical property
data within their reported
uncertainties.

14. Joule-Thomson Effect

15. Introduction:
The Joule-Thomson Effect discovered in 1852,
• Gas is forced through a small opening.
• Gas moves from a region of High to Low
Pressure.
• Pressure of both regions is kept constant.
• The process is Adiabatic.

16. Enthalpy of Gas:
According to 1st Law of Thermodynamics:
Q = ΔU + W
Since process is Adiabatic, then Q = 0, so
the equation becomes:
ΔU = -W
The work is done in two parts, leaving the
high pressure region and entering the low
pressure region i.e. W = W1 + W2
Since pressure is constant in both regions,
W1 = P1(0 - V1)
W2 = P2(V2 - 0)

17. Substituting the values, the
equation becomes:
U2 – U1 = P1V1 – P2V2
Rearranging the equation yeilds:
U1 + P1V1 = U2 + P2V2
H1=H2
The above equation shows that
the Enthalpy of gas during the
process remains constant.
From this we can deduce two
results about the change in
Temprature of the gas depending
on its nature.

18. Effect on Gas:
The Joule-Thomson Effect can
changes the Temprature of a
gas and consequently its
Internal Energy.
The effect varies depending on
factors such as:
• Nature of Gas
• Atomicity
• Temprature

19. Effect on Ideal Gas:
For Ideal Gas there will be no change
ever in Temprature and Internal
Energy because,
The gas did not perform work itself,
the first piston compressed it
through the opening which resulted
in expansion in the other region.
The work done in compression and
expansion is equal so no net change
in temprature.
The potential energy of Ideal Gas is
always zero so no conversion of
kinetic to potential which may
decrese the internal energy.

20. Effect on
Real Gas:
For Real Gas there
will be change in
Temprature and
Internal Energy
because,
The gas did not
perform work itself,
the first piston
compressed it
through the opening
which resulted in
expansion in the
other region.
The work done in
compression and
expansion is equal so
no net change in
temprature.
The potential energy
of Real Gas is not zero
so there will be
conversion of kinetic
to potential which
may decrese the
internal energy.

21. Joule-Thomson Coffecicient:
• The Joule-Thomson coffecient decribes the
change in temprature per unit change in
pressure of gas at constant enthalpy.
• It is a function of temprature and depends on
atomicity of gas.

22. Here,
• V is the Molar Volume of
Gas.
• CP is Molar Heat Capacity at
constant pressure.
• α is coffecient of thermal
expansion.
• T is temprature of gas.
From here we can deduce
three conditions for the
Joule-Thomson coffecient.

23. Effect of Temprature:
Low Temprature:
• If the initial temprature is low then the coffecient will be positive.
• The temprature of gas will decrease with decrease in pressure.
• The lower the initial temprature the faster the temprature will drop.
High Temprature:
• If the initial temprature is high then the coffecient will be negative.
• The temprature of gas will increase with decrease in pressure.
• The higher the initial temprature the faster the temprature will rise.

25. Special Points:
Inversion Temprature:
• It is the temprature at after which the sign of
coffecient is inverted.
• At this temprature the gas will behave ideally.
• The inversion is continuos.
Critical Point:
• The temprature of gasses where they behave both
as a gas and liquid at the same time.
• At a temprature lower than this the sign of
coffecient is again inverted as gas liquifies.
• The inversion is discontinuos.