KTG and Thermodynamics

Question 1

Internal Energy definition based on kinetic theory of gases

Answer 1

I.E. = Kinetic Energy of the gas as the intermolecular forces between the gaseous molecules is assumed to be zero, hence zero potential energy

Question 2

Brownian Motion

Answer 2

Random motion of the gaseous molecule

Question 3

Force imparted by one molecule on the container

Answer 3

mv^2/3L

Question 4

What is the value of Vrms, Vavg, Vmp?

Answer 4

Vrms =root(3RT/Mo)
Vavg = √8RT/πMo
Vmp = root(2RT/Mo)
The average velocity of gases is 0.

Question 5

What is the ideal gas equation?

Answer 5

PV=nRT
P = Pressure of the gas
V = volume of the gas
n = no. of moles
R = Universal Gas constant
T = Temperature

Question 6

Boyle’s Law

Answer 6

Temperature is constant
P is inversely proportional to volume

Question 7

Charle’s Law

Answer 7

Pressure is constant
Volume is directly proportional to temperature

Question 8

Gay Lussac’s Law

Answer 8

Volume is constant.
Pressure is directly proportional to temperature

Question 9

Avagadro’s Number

Answer 9

At same temperature, pressure and volumes, gases will contain equal number of molecules.
N1 = N2

Question 10

Dalton’s Law of Partial Pressure

Answer 10

Total pressure exerted by a mixture of non-reactive gases is equal to sum of individual pressure exerted by each gas

Question 11

Graham’s law of diffusion

Answer 11

Rate of diffusion of gases are inversely proportional to square root of of the density of the gas

Question 12

Mean Free Path

Answer 12

It is the average distance travelled by a gaseous molecule between any two successive collision.

Question 13

Degree of Freedom

Answer 13

Total number of independent term in the kinetic energy of the gaseous moelcule

Question 14

DOF of monoatomic gaseous molecule and its internal energy

Answer 14

3(Translational Kinetic Energy)
Total internal energy = 3nrt/2

Question 15

DOF of diatomic gaseous molecule and its internal energy

Answer 15

DOF = 5(3 translational and 2 rotational)
U = 5nRT/2
U = 7nRT/2(For very high temperature, a vibrational KE is also added)

Question 16

DOF of polyatomic gaseous molecule (Linear) and and its internal energy

Answer 16

DOF = 5(3 translational and 2 rotational)
U = 5nRT/2

Question 17

DOF of polyatomic gaseous molecule (Non-Linear) and and its internal energy

Answer 17

DOF = 6(3 translational and 3 rotational)
U = 3nRT

Question 18

Mayer’s Formula

Answer 18

Cp=Cv+R

Question 19

Value of change in internal energy

Answer 19

nCv△T

Question 20

Types of thermodynamic system

Answer 20

Open System - Both energy and matter can be exchanged between system and surrounding
Closed System - Only energy exchange is possible
Isolated System - Neither energy nor matter can be exchanged between system and surroundings

Question 21

Work done by an ideal gas

Answer 21

dW = PdV
Work done is the area under the PV curve

Question 22

Zeroth Law of Thermodynamics

Answer 22

If A and B are in thermal equilibrium, and B and C are in thermal equilibrium, then A and B are in thermal equilbrium.

Question 23

First Law of Thermodynamic

Answer 23

Q = △u + Workdone

Question 24

What is the specific heat capacity?

Answer 24

Q=mS△T
m =mass of the substance
△T = Change in temperature

Question 25

Molar Heat Capacity

Answer 25

Q = nC△T n = no. of moles

Question 26

Internal Energy is a function of

Answer 26

△T It only depends upon the initial and final point, and not on the path followed. Hence is a state function

Question 27

Molar Heat Capacity at constant volume and pressure

Answer 27

Constant Volume: Q = nCv△T Constant Pressure: Q = nCp△T

Question 28

Work done by Isobaric, Isochoric, Adibatic and Isothermal

Answer 28

W = nr△T, 0, nRTlnv2/v1 or nRTlnP1/P2, -nR△T/y-1

Question 29

Conditions for adibatic process

Answer 29

PV^y = Constant TV^y-1 = Constant P^1-yT^y = Constant

Question 30

Work done by polytropic process(PV^x = constant)

Answer 30

Work done = nR(T1-T2)/x-1

Question 31

Free Expansion of a gas

Answer 31

Expansion of gas by doing no work done, and the moles are accordingly distributive

Question 32

Cvmix

Answer 32

n1Cv1+n2Cv2/(n1+n2)

Question 33

Cpmix

Answer 33

n1Cp1+n2Cp2/(n1+n2)

Question 34

ymix is

Answer 34

Cpmix/Cvmix

Question 35

Latent Heat

Answer 35

Amount of heat required to change the state or phase of a substance at their melting point and boiling point without the change in temperature

Question 36

Latent Heat of Fusion

Answer 36

Heat required to change 1unit of ice at 0 degree to 1 unit of water at 0 degree without any change in temperature

Question 37

Latent Heat of Vaporisation

Answer 37

Heat required to change 1unit of water at 100 degree to 1 unit of water vapour at 100 degree without any change in temperature

Question 38

Efficiency of cyclic process

Answer 38

Total work done/ Heat absorbed

Question 39

Efficiency of the heat engine

Answer 39

Total Work/Heat Absorbed 1-Q2/Q1, where Q2 is the heat gain without change in temperature and Q1 is the heat giving change in temperature

Question 40

Clausius Statement

Answer 40

It is impossible for self acting engine to transfer the heat from colder body to hotter body without external aid.

Question 41

Kelvin-Planck Statement

Answer 41

It is impossible to design an engine that extracts heat and fully utilised it into work without producing any other effect.

Question 42

Coefficient of Performance

Answer 42

Heat Absorbed/Work done