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