Thermodynamics

Question 1

Zeroth Law of Thermodynamics

Answer 1

• states that objects are in thermal equilibrium when they are at the same temperature
• objects in thermal equilibrium experience no net exchange of heat energy

Question 2

Temperature

Answer 2

the average kinetic energy of the particles that make up a substance

Question 3

Thermal Expansion

Answer 3

describes how a substance changes in length or volume as a function of the change in temperature

Question 4

System

Answer 4

a thermodynamic system is the portion of the universe that we are interested in observing

Question 5

Surroundings

Answer 5

include everything that is not part of the system

Question 6

Isolated Systems

Answer 6

do not exchange matter or energy with the surroundings

ex. bomb calorimeter

Question 7

Closed Systems

Answer 7

exchange energy but not matter with their surroundings

ex. movable pistons, gases in vessels

Question 8

Open Systems

Answer 8

exchange both energy and matter with their surroundings

ex. boiling water in pot, uncontained combustion

Question 9

State Functions

Answer 9

• are pathway independent and are not themselves defined by a process
• pressure, density, temperature, volume, enthalpy, internal energy, Gibbs free energy, entropy

Question 10

Process Functions

Answer 10

• describe the pathway from 1 equilibrium state to another
• work and heat are process functions

Question 11

First Law of Thermodynamics

Answer 11

is a statement of the conservation of energy: the total energy in the universe can never decrease or increase

Question 12

Total Internal Energy

Answer 12

for a closed system, the total internal energy is equal to the heat flow into the system minus the work done by the system

Question 13

Heat

Answer 13

is the process of energy transfer between 2 objects at different temperatures that occurs until the 2 objects come into thermal equilibrium

Question 14

Specific Heat

Answer 14

is the amount of energy necessary to raise one gram of a substance by 1 degree Celsius or Kelvin

Question 15

Conduction

Answer 15

is the direct transfer of energy from molecule to molecule through molecular collisions
- there must be direct physical contact

Question 16

Convection

Answer 16

• is the transfer of heat by the physical motion of fluid over a material
• involves flow, can only be done by liquids or gases

Question 17

Radiation

Answer 17

• is the transfer of energy by electromagnetic waves
• radiation can transfer energy thru a vacuum

Question 18

Specific Heat of Water

Answer 18

is 1 cal/g*K

Question 19

Heat of Transformation

Answer 19

during a phase change, heat energy causes changes in the particles’ potential energy and energy distribution (entropy), but not kinetic energy, therefore there is no change in temperature

Question 20

Fusion/Melting

Answer 20

Solid to Liquid

Question 21

Freezing/Solidification

Answer 21

Liquid to Solid

Question 21

Boiling/Evaporation/Vaporization

Answer 21

Liquid to Gas

Question 22

Condensation

Answer 22

Gas to Liquid

Question 23

Sublimation

Answer 23

Solid to Gas

Question 24

Deposition

Answer 24

Gas to Solid

Question 25

Isothermal Processes

Answer 25

• the temperature is constant
• change in internal energy is 0 (ΔU = 0)

Q = W

Question 26

Adiabatic Processes

Answer 26

• no heat is exchanged (Q = 0)

ΔU = W

Question 27

Isobaric Processes

Answer 27

the pressure is held constant

Question 28

Isochoric Processes

Answer 28

• the volume is held constant
• work done by or on system is 0 (W=0)

ΔU = Q

Question 29

Second Law of Thermodynamics

Answer 29

states that in a closed system, energy will spontaneously and irreversibly go from being localized to being spread out (dispersed)

Question 30

Entropy

Answer 30

is a measure of how much energy has spread out or how spread out energy has become

Question 31

Microstates

Answer 31

in a statistical level, as the number of available microstates increases, the potential energy of a molecule is distributed over that larger number of microstates, increasing entropy

Question 32

Natural Process

Answer 32

• Every natural process is irreversible
• under highly controlled conditions, certain equilibrium processes such as phase changes can be treated as essentially reversible

Question 33

Temperature Conversions

Answer 33

Question 34

Thermal Expansion Equation

Answer 34

α = coefficient of linear expansion (K^-1)
L = initial length

Question 35

Volume Expansion Equation

Answer 35

β = coefficient of volumetric expansion
β = 3α (equals 3 times coefficient of linear expansion)

Question 36

First Law of Thermodynamics Equation

Answer 36

work done by system = expansion

Question 37

Heat Gained or Lost (phase change)

Answer 37

L = latent heat
W= mL

Question 38

Entropy and Heat

Answer 38