GROUP-3 thermodynamics laws, Brownian motion, Van der Waals
equation of state, Entropy
PHYSICS PRESENTATIONGroup-3SUBMITTED BY
Md Mosharof Hosen-151002051Mohammad Tareq
Hosain-151002017Mahmudul
Hasan-151002030S.N.I.Emon-151002022Jannatul Nayem
Nissan-151002064Azajul Islam Rocky-151002073SUBMITTED TO
Romena AkterFaculty of EEECourse Title: Physics Course Title:
Phy 101Sec- ADepertment of Computer Science & Engineering
GROUP-3Assignment topics is:
Thermodynamics laws, Brownian motion,Van der Waals equation of
state,Entropy.
POINTS OF DISCUSSIONWhat is thermodynamics ?Thermodynamics
laws.Definition of Brownian Motion.What is Brownian movement ?How
are the brownian motion different from diffusion?Definition of Van
der Waals equation of state.Van der Waals equation of
state.Defination of EntropyEntropy of the SystemEntropy on the
Molecular ScaleEntropy ChangesAny Questions ???
What is Thermodynamics ?Thermodynamics: Thermodynics is the
field of physics that deals with the relationship between heat and
other propertis ( such as: pressure,density,temparature etc ) in a
substancs.
Thermodynamics laws :The four laws of thermodynamics define
fundamental physical quantities that characterize thermodynamics
systems. The four laws of thermodynamics are: Zeroth law of
thermodynamics: If two systems are in thermal equilibrium
respectively with a third system, they must be in
thermalequilibrium witheach other. This lawhelps define thenotion
of temperature.
Thermodynamics laws :First law of thermodynamics: In all
transformation the amount of it supply to assistant must be balance
by the sum of the gain in internal energy of the system due to the
rise in temperature and the external work done.
Mathmatically,dQ=dU+where, dQ=heat supplied dU=change in internal
energy =heat equivaleat of the work done
Thermodynamics laws :Second law of thermodynamics: In a natural
thermodynamic process, the sum of the entropies of the
participating thermodynamic systems, increases.
Equivalently,perpetual motion machines the second kind are
impossible.
Thermodynamics laws :Third law of thermodynamics: The entropy of
a system approaches a constant value as the temperature approaches
absolute zero.With the exception of glasses the entropy of a system
at absolute zero is typically close zero,andis equal to the log of
themultiplicity of thequantum ground state.
Definition of Brownian MotionBrownian Motion: The brownian
motion is the random movemement of microscopic particles suspended
in a liquid or gas, caused by collisions with molecules of the
surrounding medium.It was named for the Scottish botanist Robert
Brown, the first to study such fluctuations (1827).This simple
demonstration ofEinstein's explanation for Brownianmotion shows
little particles batting about a more massive one , and what
Brownian Motion:it would look like if you could see only the
massive one through a microscope. Einstein showed that the overall
visible motion, averaged over many observations, exactly matches
what you would expect if the little particles were atoms or
molecules.
What is Brownian movement ?Brownian movement: the random motion
of small colloidal particles suspended in a liquid or gas medium,
caused by the collision of themedium's molecules with theparticles.
Also called Brownianmovement.
How are the brownian motion different from diffusion?Brownian
motion differs from diffusion most significantly in that diffusion
results in a net transfer of material from one location to another
on a macro scale, while Brownian motion is randomly directed motion
of molecules and similarly sized particles and does not result in
net mass transfer from one place to another.
Definition of Van der Waals equation: Van der Waals equation:
The van der Waals equation is an equation of state for a fluid
composed of particles that have a non-zerovolume and a pairwise
attractiveinter-particle force (such as thevan der waals force).Not
all gassesact ideally. This is especially truewhen one approaches
theconditions for the gas to condense.Van der Waals state equation
had
Van der Waals
Van der Waals equation:become the most famous among those
equations that described the behavior of real gases. Afterwards,
Clausius, Virial, and others also proposed state equations on real
gases, but they were all based on van der Waals equation.
Gases and Liquids are connected continuously
Van der Waals equation of state: The ideal gas law, PV = nRT,
can be derived by assuming that the molecules that make up the gas
have negligible sizes, that their collision with themselves and the
wall are perfectly elastic, and that the molecules have no
interactions with each other.
The van der Waal's equation is a second order approximation of
the equation of state of a gas that will work even when the density
of the gas is not low.
Van der Waals equation of state: Here a and b are constants
particular to a given gas.Some van der Waals Constants
Substancea(J.
m3/mole2)b(m3/mole)Pc(MPa)Tc(K)Air.13583.64x10-53.77133 KCarbon
Dioxide (CO2) .3643 4.27x10-5 7.39 304.2 K Nitrogen (N2) .1361
3.85x10-5 3.39 126.2 K Hydrogen (H2) .0247 2.65x10-5 1.30 33.2 K
Water (H2O) .5507 3.04x10-5 22.09 647.3 K Ammonia (NH3) .4233
3.73x10-5 11.28 406 K Helium (He) .00341 2.34x10-5 0.23 5.2 K Freon
(CCl2F2) 1.078 9.98x10-5 4.12 385 K
Van der Waals equation of state: The parameter b is related to
the size of each molecule. The volume that the molecules have to
move around in is not just the volume of the container V, but is
reduced to ( V - nb ). The parameter a is related to intermolecular
attractive force between the molecules, and n/V is the density of
molecules. The net effect of the intermolecular attractive force is
to reduce the pressure for a given volume and temperature. When the
density of the gas is low (i.e., when n/V is small and nb is small
compared to V) the van der Waals equation reduces to that of the
ideal gas law.
Van der Waals equation of state: One region where the van der
Waals equation works well is for temperatures that are slightly
above the critical temperature Tc of a substance
Van der Waals equation of state: Observe that inert gases like
Helium have a low value of a as one would expect since such gases
do not interact very strongly, and that large molecules like Freon
have large values of b.
There are many more equations of state that are even better
approximation of real gases than the van der Wall equation.
Defination of Entropy:Entropy: In thermodynamics , entropy
(usual symbols) is a measure of the number of specific ways in
which a thermodynamics system be arranged, commonly understood as a
measure of disorder .According to the second law of thermodynamics
the entropy of an isolated system maximum entropy. Systems that are
not isolated may decrease in entropy, provided they increase the
entropy of their environment by at least that same amount. Since
entropy is a state function, the change in the entropy of a system
is the same for any process that goes from a given initial state to
a given final state, whether the process is reversible or
irreversible.
Entropy of the System: Is greater in: Gases than solids. Larger
volumes of gases than smaller volumes. Larger number of gas
molecules than smaller number of gas molecules. The change in
entropy (S) of a system was originally defined for a
thermodynamically reversible process as:
Example: Which has more entropy in its system? H2O (s) orH2O
(g)
Entropy on the Molecular Scale Ludwig Boltzmann described the
concept of entropy on the molecular level.
Temperature is a measure of the average kinetic energy of the
molecules in a sample.
Entropy on the Molecular Scale Molecules exhibit several types
of motion: Translational: Movement of the entire molecule from one
place to another. Vibrational: Periodic motion of atoms within a
molecule. Rotational: Rotation of the molecule on about an axis or
rotation about bonds.
Entropy on the Molecular Scale Boltzmann envisioned the motions
of a sample of molecules at a particular instant in time. This
would be akin to taking a snapshot of all the molecules. He
referred to this sampling as a microstate of the thermodynamic
system.
Entropy on the Molecular Scale Each thermodynamic state has a
specific number of microstates, W, associated with it. Entropy isS
= k lnWwhere k is the Boltzmann constant, 1.38 1023 J/K.
Entropy on the Molecular Scale The number of microstates and,
therefore, the entropy tends to increase with increases in
Temperature. Volume (gases). The number of independently moving
molecules.
Entropy Changes In general, entropy increases whenGases are
formed from liquids and solids.Liquids or solutions areformed from
solids.The number of gasmolecules increases.The number of
molesincreases.
ANY QUESTIONS ???THANKS TO ALL