Cheat sheet for Heat and Thermodynamics

Cheat sheet for Heat and Thermodynamics

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

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