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   thermodynamics revision sheet
posted on 16 Mar 2009 20:19:10 IST    768 views    5 comments
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                                            Thermodynamics Revision Sheet

 

Temperature
TF=9/5 TC + 32°
TC = TK - 273.15 K
The pressure,volume and temperature in kelvin of such gases obey the equation
PV=nRT ----(1)
Thermal expansion

ΔL=αLΔT


Specific Heat Capacity=ΔQ/mΔT




Gas Laws
Boyles Law: PV=constant
Charles Law : V/T=constant
Dalton Law of Partial Pressure: P=P1 + P2 +P3
Root mean Square Velocity
Vrms=√3RT/M
Mean  Velocity
Vm=√8RT/&#960M
Most Probable Velocity
V=√2RT/M
Also
Vrms > Vm > V

Average kinetic Energy of Gas=3/2nRT

First law of Thermodynamics

ΔU=Q-W


Gas Processes

Isothermal Process : PV=constant ,ΔU=0,Q=W,Molar Specific Heat=infinity
Adaibatic Process : PVy=constant,Q=0,ΔU=-W,Molar Specific Heat=zero
Polytropic Process : PVn=constant,Molar Specific Heat=[R/(y-1) + R/(1-n)]
Volume Constant : P/T=constant W=0,ΔU=Q,Molar Specific Heat=Cv
Pressure Constant : V/T=constant ΔU=Q-W ,Molar Specific Heat=CP

Internal energy depends on Temperature.
So for same temperature change ΔT
nCvΔT=Q1-W1=Q2-W2=Q3-W3

Molar Specfic Heat Capacity of any process is given by

C=Cv + Pdv/ndT where n is no of moles of the gas

Workdone by Gas= ∫PdV

Heat Conduction

Q=-KAdT/dx

Wein displacement lawλT4=Constant

Stefan's Law
Q=eσT4

Newton law of Cooling

dT/dx=b(T-Ts)

 

 

 

Problem Solving tips

1.     Net Heat flow at a junction is Zero

2.     Internal Energy does not depend on the path

3.     Internal Energy in a cyclic  Process is zero

4.     Heat is positive when given to the system and negative when taken out of the system

5.     Workdone by the system on the surrounding is positive while the workdone on the system by the surrounding is megative


 

 

TIP FOR CONVERSION - TEMPERATURE UNITS:

 

LET TEMP IN A SYSTEM (LIKE CELSIUS, KELVIN ETC)   BE  -   T

AND FREEZING POINT OF WATER IN THE SYSTEM BE -  F

AND BOILING POINT OF WATER IN THE SYSTEM BE - B

 

THEN,

 

T - F / B - F  = A CONSTANT

 

ie,  T- 0/ 100 - 0   (in celsius) = T - 32 / 212 -32 (fahrenhiet) = T - 273 / 373 - 273 (kelvin scale)

 

or,   C/100 = (F - 32) / 180 = (K-273)/ 100

 

 

 

About the Author:
Arun George (104)

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Olaaa!! Perrrfect answer.  18  [25 rates]

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shangi  124 is offline comment by shangi 124      (posted on 16 Mar 2009 20:23:02 IST)
    thanx.
Arun George is offline comment by Arun George      (posted on 16 Mar 2009 23:24:32 IST)
    pls post comments ppl
taran is offline comment by taran      (posted on 17 Mar 2009 00:55:45 IST)
    thanks
sneha is offline comment by sneha      (posted on 17 Mar 2009 10:25:33 IST)
    good job
Arun George is offline comment by Arun George      (posted on 17 Mar 2009 23:26:11 IST)
    T - F / B - F = A CONSTANTthis formulae can be used for converting to any unit............GENERAL FORMULAE.
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