Laws Of Thermodynamics Flashcards
Thermodynamics
Zeroth law
First law
Second law
Third law
Thermal equilibrium
Energy in = energy out
Total entropy of an isolated system increases over time in an irreversible system
Every substance has finite positive entropy, but at absolute zero of temp, entropy may become zero
Internal energy for isolated sytem
O
First law involves work and heat. True or false
True
First law involves work and heat. True or false
True
Heat expressed as ___ in constant volume
Internal energy
Heat expressed as ___ in constant pressure
Enthalpy
Recall work equations under different conditions
Free expansion
Against a constant external pressure
Isotherms reversible
Total heat content of system
Enthalpy
Give pressure and volume dependence of internal energy
Give temperature and pressure dependence of enthalpy
Give temperature and pressure dependence of enthalpy
Recall heat capacity values of ideal gases
Monoatomic
Diatomic/linear polyatomic
Nonlinear polyatomic
Cp
2.5R
3.5R
4R
Cv
1.5R
2.5R
3R
Gamma
5/3
7/5
4/3
Note: Gamma= Cp/Cv
Recall heat transactions
Endothermic
Exothermic
∆H>0, surroundings get cooler, system warms
∆H<0, surroundings get warmer, system cools
Recall 2 ways of calorimetry.
Coffee cup calorimeter
Bomb calorimeter
Constant pressure, involves small heat changes
Constant volume, involves high amount of heat
and gaseous product
Study of heat accompanying chemical changes
Thermochemistry
Recall standard enthalpy of formation
Recall standard enthalpy of combustion and it’s special case
Shows temp dependence of reaction enthalpy
Kirchoffs law. Recall formula
Enthalpy is extensive. Discuss
Standard enthalpy of overall reaction is the sum of individual reactions into which the reactions might be subdivided
Hess’ law
Phase change occurs at constant ___
Pressure. Thus thermodynamic equation for heat and entropy are for isobaric conditions. Recall formulas
Heat accompanying temp change
Sensible heat. Recall formula
Heat accompanying phase change
Latent heat. Recall formula
∆S (+) denotes ___
More disorder
Thermo implications
Impossible for the system oerating cyclically to fully convert heat into work (Kelvin plank)
Impossible for a system operating cyclically and spontaneously to transfer heat from lower to high temp (clausius)
In reversible adiabatic expansion heat and entropy is equal to
O
Recall carnot cycle. Identify where does heat enters and exits.
Converts heat into usable work with release of residual heat
Carnot Heat Engine. Recall efficiency formual
Convert work in order to remove a certain amount of heat
Carnot refrigerator. Recall COP
Converts work in order to supply certain amint of heat
Carnot heat pump. Recall COP
Recall heating curve of water
Region 1: Sensible heat (solid)
Region 2: latent heat (solid and liquid)
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