Thermodynamics

Question 1

Extensive properties

Answer 1

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

Question 2

State properties

Answer 2

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

Question 3

Path functions

Answer 3

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

Question 4

Intensive properties

Answer 4

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

Question 5

Equation of state

Answer 5

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

Simplest: PV = nRT

Question 6

State of equilibrium

Answer 6

Thermal equilibrium
Mechanical equilibrium
Chemical equilibrium

Question 7

Chemical equilibrium

Answer 7

The chemical composition of the system does not vary

Question 8

Mechanical equilibrium

Answer 8

The pressure is the same everywhere in the system

Question 9

Isobaric

Answer 9

Occurring at constant pressure

Constant P

Question 10

Isochoric

Answer 10

Occurring at constant volume

Constant V

Question 11

Isothermal

Answer 11

Occurring at constant temperature

Constant T

Question 12

Adiabatic

Answer 12

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

Question 13

Cyclic

Answer 13

Initial state = final state

Question 14

Adiabatic processes

Answer 14

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

Question 15

Ideal gas

Answer 15

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

Question 16

Internal energy (U)

Answer 16

Sum of the energies of the sons Titus the molecules

Question 17

Van der Waals Equation

Answer 17

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

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

b = constant for excluded volume

Question 18

Work and heat

Answer 18

Delta U = Q + W

Question 19

Work

Answer 19

W = -Pext (Vf-Vi)

Involves the movement of matter

W = PdV for reversible processes

Question 20

Heat

Answer 20

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

Stored as kinetic and potential energy

Question 21

If Q is added to a system

Answer 21

Q = (+)

Question 22

Heat is removed from a system

Answer 22

Q = (-)

Question 23

If work is done on a system

Answer 23

W = (+)

Question 24

If work is done by a system

Answer 24

W = (-)

Question 25

1st Law of Thermodynamics

Answer 25

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

Question 26

1st Law of Thermodynamics

Answer 26

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

Question 27

Adiabatic process and 1st Law

Answer 27

``` U = -W Q = 0 ```

Question 28

Enthalpy

Answer 28

H = U + PV dH = dU + d(PV) = dU + PdV + VdP Constant pressure: dH = dU + PdV

Question 29

Heat capacity (Cp & Cv)

Answer 29

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

Question 30

Heat capacity at constant volume (Cv)

Answer 30

Cv = (dQ/dT)v Under this restriction: W = 0 Under this restriction: dU = dQ Cv = (dU/dT)v

Question 31

Heat capacity at constant pressure (Cp)

Answer 31

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

Question 32

Cp & Cv written in other forms

Answer 32

dU = CvdT dH = CpdT Always valid for ideal gas

Question 33

Cp & Cv at low pressure

Answer 33

Real-gas behavior in low pressure resembles idea gas so P -> 0 limit Cp - Cv = R R = gas constant

Question 34

Ratios of heat capacities

Answer 34

Y = Cp/Cv R/Cv = Y - 1

Question 35

Ideal gas state

Answer 35

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

Question 36

Ideal gas heat capacities

Answer 36

``` igCv = (3/2)R igCp = (5/2)R Y = 1.67 ```

Question 37

Ideal heat capacities for diatomic gases

Answer 37

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