Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Chemistry for JEE

Class 11 : Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

The document Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev is a part of the Class 11 Course Chemistry for JEE.
All you need of Class 11 at this link: Class 11

POLYTROPIC PROCESS
PVx = Const

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev
Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev
Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

MOLAR HEAT CAPACITY OF POLYTROPIC PROCESS
dU = dq + dW
nCVdT = nCmdT (-PdV)

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev
PV = nRT
KV-x V = nRT
kV-x 1 = nRT
Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev
Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Limitations of First law of Thermodynamics
(a) First law of thermodynamics does not give information regarding the direction of propagation of a process
(b) First law of thermodynamics does not tell us why an equilibrium is attained.
(c) First law of thermodynamics does not tell us when an equilibrium will be attained.
(d) First law of thermodynamics does not give information about why there can not be 100 percent conversion of heat into work

Second Law of Thermodynamics
Statement(I) : Second law of thermodynamics states that heat can never be converted into work with 100% efficiency
Statement(II) : No engine in this world can be constructed which operates in cycles and converts all the heat from source to work.
Statement(III) : No refrigertator can be designed which operates in cycles and rejects heat from sink to source, perpetually (self - functioning).
Entropy : Entropy is the direct measurment of randomness or disorderness. Entropy is an extensive property & it is a state function
Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev 
for reversible process. entropy is related with complexity of the molecule within the system.
EtOH > MeOH
C2H6 (g) > C2H5(g)
N2O4 > NO2
O2 > N2 (molecular wt.)
Gas > Liq > Amorphous solid > crystalline solid

Entropy always increases in the following process 
(a) s → ℓ, ℓ → g, s → g,
(b) Isothermal expansion of ideal gas.
(c) Mixing of two non reacting gases.
(d) In chemical reaction in which

Δng > 0
(e) Heating of any substance

Classification of process Based on spontaneity
Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Why Spontaneity
Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Points to ponder: 
Why a system always moves towards disorderness ?
Answer: A system moves towards disorderness because the probability of moving towards disorderness is very high.

DISORDERNESS

For Reversible process: 

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Note : Irreversible process

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

The entropy change for an irreversible process can be calculated by substituting it with equivalent reversible process. Both will have same entropy change.

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Entropy Change of Universe

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

ΔSuniverse = ΔSsystem ΔSsurrounding

Spontaneity

1. ΔSuniverse > 0 ⇒ Spontaneous 

2. ΔSuniverse = 0 ⇒ Equilibrium 

3. ΔSuniverse < 0 ⇒ Non-spontaneous. 

Entropy Change

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev 

Calculation of entropy change

(A) General heating or cooling

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

If C is temperature independent

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

If C is a function of Temperature

C = a + bT

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

(B) In phase transformation 

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

*A(l)Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev A(g).

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

*A(s)Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev A(g) 

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

(C) Entropy change during chemical reaction. 

aA bB → cC dD
ΔSº = entropy of product - entropy of reac tan t

For any chemical reaction

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

(D) Calculation of entropy change during expansion/compression of ideal gas from P1V1T1 to P2V2T2

From Ist law of thermodynamics

dE = dq + dW

dq = - dW + dE

TdS = PdV + nCVdT

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

For ideal gas

ΔS = nCVln Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev + nRln Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev. Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

= nCVln Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev nRln Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev nRln Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Calculation of entropy change during isothermal Expansion; 

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

because

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Wrev > Wirr 

ΔStotal = +ve

Calculation of entropy change during isothermal compression. 

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

qirr + wirr = 0

| wirr | > | wrev |

< 0 >0

⇒ | qirr | > | qrev |

Calculation of entropy change during for adiabatic expansion of ideal gas.

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

For reversible process 

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Where K is constant

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev


For irreversible process 

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

This means that the final temperature of irreversible process is greater than reversible process.

ΔS = nCV ln Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev+ nRln Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

                   Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev           Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev
                    -ve             +ve
      = nCVln Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev - nCVln Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

⇒ T'2 > T2

⇒ ΔS = +ve

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

⇒ ΔStotal = +ve


Calculation of entropy change in adiabatic compression. 

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

dT = 110

For reversible

(T2 - T1) = 100K

T2 = T1 + 100 K

for irreversible
T'2= T1 110 K
T'> T2

Polytropic Process, Entropy Change and Spontaneity Class 11 Notes | EduRev

Offer running on EduRev: Apply code STAYHOME200 to get INR 200 off on our premium plan EduRev Infinity!

Related Searches

Entropy Change and Spontaneity Class 11 Notes | EduRev

,

Viva Questions

,

Entropy Change and Spontaneity Class 11 Notes | EduRev

,

Important questions

,

past year papers

,

Objective type Questions

,

Exam

,

video lectures

,

Extra Questions

,

Previous Year Questions with Solutions

,

Sample Paper

,

ppt

,

Semester Notes

,

mock tests for examination

,

shortcuts and tricks

,

MCQs

,

pdf

,

Polytropic Process

,

study material

,

Free

,

Summary

,

Polytropic Process

,

Entropy Change and Spontaneity Class 11 Notes | EduRev

,

practice quizzes

,

Polytropic Process

;