Thermodynamics Flashcards

1
Q

Extensive properties

A

Capacity factors
Depend on the amount of matter present in terms of mass
They are equal to the sum of the parts/ additive

EX: total volume/total energy of a system

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2
Q

State properties

A

Defines state of a system
Properties are interrelated
Does not depend on path taken
Temperature, pressure, volume, internal energy, enthalpy, entropy

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3
Q

Path functions

A

Such as heat (Q) and work (W).
Path dependent properties
I exact differentials

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4
Q

Intensive properties

A

Intensity factor do not depend on the quantity of material present
I.e. Temperature, viscosity, molar volume, density, pressure, refractive index
At equilibrium they are the same for every pet of the system

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5
Q

Equation of state

A

Equation that relates the thermodynamic properties of a system in a state of equilibrium

Simplest: PV = nRT

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6
Q

State of equilibrium

A

Thermal equilibrium
Mechanical equilibrium
Chemical equilibrium

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7
Q

Chemical equilibrium

A

The chemical composition of the system does not vary

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8
Q

Mechanical equilibrium

A

The pressure is the same everywhere in the system

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9
Q

Isobaric

A

Occurring at constant pressure

Constant P

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10
Q

Isochoric

A

Occurring at constant volume

Constant V

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11
Q

Isothermal

A

Occurring at constant temperature

Constant T

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12
Q

Adiabatic

A

Occurring with no exchange of heat between the system and its surroundings
Q = 0

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13
Q

Cyclic

A

Initial state = final state

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14
Q

Adiabatic processes

A

Is enclosed by an adiabatic boundary = temperature is independent of its surroundings
Never achieves thermal equilibrium with its surroundings
I.e. Flow of heat through the boundary = 0

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15
Q

Ideal gas

A

Composed of gases in random motion
Collision are perfectly elastic
Molecules don’t attract each other
U depend only on T and # of molecules

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16
Q

Internal energy (U)

A

Sum of the energies of the sons Titus the molecules

17
Q

Van der Waals Equation

A

((P+an^2)/V^2) (V-nb) = nRT

a = constant for force of interactions b/w gas particles

b = constant for excluded volume

18
Q

Work and heat

A

Delta U = Q + W

19
Q

Work

A

W = -Pext (Vf-Vi)

Involves the movement of matter

W = PdV for reversible processes

20
Q

Heat

A

Is thermal energy that flows from a hot body to a cold one

Stored as kinetic and potential energy

21
Q

If Q is added to a system

A

Q = (+)

22
Q

Heat is removed from a system

A

Q = (-)

23
Q

If work is done on a system

A

W = (+)

24
Q

If work is done by a system

A

W = (-)

25
Q

1st Law of Thermodynamics

A

The total energy of a system and its surroundings is always constant

26
Q

1st Law of Thermodynamics

A
U = Q - W
I = total internal energy
Q = heat added to the system
W = work done by the system
dU = Q - W
27
Q

Adiabatic process and 1st Law

A
U = -W
Q = 0
28
Q

Enthalpy

A

H = U + PV

dH = dU + d(PV) = dU + PdV + VdP

Constant pressure: dH = dU + PdV

29
Q

Heat capacity (Cp & Cv)

A

The thermal energy that must be added to raise the temperature of a system by 1 C, under specific conditions

Can calculate heat capacity of reversible processes, for which the path is fully specified

30
Q

Heat capacity at constant volume (Cv)

A

Cv = (dQ/dT)v

Under this restriction: W = 0
Under this restriction: dU = dQ

Cv = (dU/dT)v

31
Q

Heat capacity at constant pressure (Cp)

A

Cp = (dQ/dT)p
Cp= (dH/dT)p
Cp is a system property

32
Q

Cp & Cv written in other forms

A

dU = CvdT

dH = CpdT

Always valid for ideal gas

33
Q

Cp & Cv at low pressure

A

Real-gas behavior in low pressure resembles idea gas so P -> 0 limit

Cp - Cv = R

R = gas constant

34
Q

Ratios of heat capacities

A

Y = Cp/Cv

R/Cv = Y - 1

35
Q

Ideal gas state

A

State achieved when a real gas is compressed to a finite pressure while retaining ideal gas behavior

36
Q

Ideal gas heat capacities

A
igCv = (3/2)R
igCp = (5/2)R
Y = 1.67
37
Q

Ideal heat capacities for diatomic gases

A
igCv = (5/2)R
igCp = (7/2)R
Y = 1.40