Chapter 3 - Thermodynamics

Question 1

Zeroth Law of Thermodynamis

Answer 1

• things in thermal contact, no net heat will flow between objects
  
  • hot tea in a cup and stir with metal straw using your hand. All three are in thermal equilibrium

Question 2

Temperature

Answer 2

• Proportional to the average kinetic energy of the particles that make up that substance
• heat moves from hot to cold

Question 3

Heat

Answer 3

• transfer of thermal energy from hotter object to one with lower temperater
  
  • if no net flow of heat then the two are in ​thermal equilibrium

Question 4

ansolute zero

Answer 4

• theoretical temperature in which there is no kinetic energy/thermal energy
• freezing point of water is 273.13 K

Question 5

Temperature Conversions Equations

Answer 5

• F = 9/5C + 32
  
  • K = C + 273

Question 6

Thermal Expansion Equation

Answer 6

• When products are being heated they will increase in length
• When products are being cooled they will decrease in length
• equation:

ΔL = αLΔT

α is the coefficient of linear expansion and is a constant

units are K^-1

Question 7

Volumetric Thermal Expansion

Answer 7

• ΔV = βLΔT

β is the coefficient of volumetric expansion and is approcimately three times the size of the coefficient of linear expansion

Question 8

Isolated System

Answer 8

• CANNOT exchange energy or matter with their surroundings
• total change in internal energy must be zero
  
  • bomb calorimeter is an example

Question 9

Closed System

Answer 9

• CAN exchange energy but CANNOT exchange matter
• most of the systems on TEST DAY will be closed systems
  
  • example are experiments with gases in vessels with movable pistons

Question 10

Open System

Answer 10

• CAN exhcnage both energy and matter with surroundings
  
  • some examples constitute a boiling pot of water, human beings , uncontained combustion interactions

Question 11

State Functions

Answer 11

• Pressure, density, temperature, volume, enthalpy, internal energy, Gibbs free energy, and Entropy
• These are functions that are independent of the path taken to get to a particular equilibrium state

Question 12

Process Functions

Answer 12

• are those that descrbie the path taken to get from one state to another
  
  • some examples are like work and heat

Question 13

What occurs to the energy in a system with absense of non-conservative forces?

Answer 13

The sum of kinetic and potential energies will remain constant in the system

Question 14

First Law of Thermodynamics

Answer 14

• states the change in internal energy of a system is equal to energy transferred in form of heat to the system, minus the amount of energy transferred from the system in the form of work

ΔU = Q - W

Question 15

Second Law of Thermodynamics

Answer 15

• objects that are in thermal contact will eventually reach thermal equilibrium
• heat energy will flow from higher temperature object to that of lower temperature

Question 16

Heat

Answer 16

• Is the transfer of heat energy from one object to another
• SI unit for heat is Joule (J)

1 Cal = 1000 cal = 4184 J = 3.97 BTU

Question 17

Conduction

Answer 17

• Heat transfer through physical contact
• Metals are the best conductors and gasses are the poorest

Question 18

Convection

Answer 18

• This is the transfer of heat through the movement of fluids or gases
  
  • some examples are convection ovens that use fans to circulate the radiation heat throughout the oven; another would be the flow of heat in a automobile radiator

Question 19

Radiation

Answer 19

• This is the transfer of heat energy through electromagnetic waves.
• this process can occur within a vacuum unlike conduction and convection

Question 20

What occurs to temperature when there is a phase change occuring?

Answer 20

The temperature will remain unchaged

Question 21

Specific Heat

Answer 21

• (c)
• is defined as the amount of energy required to raise one gram of a substance by one degree Celsius or one unit kelvin

i.e specific heat of water is 1 cal/g x K or 4.184 J / g x K

Question 22

Equation that relates heat gained/lost by an object and change in temperature of that object

Answer 22

q = mcΔT

Question 23

how do you calculate the amount of heat that is added or removed from a system that is undergoing a phase change?

Answer 23

q = mL

L = heat of transformation or latent heat

Question 24

Phase change: Liquid to solid

Answer 24

freezing or solidification

Question 25

Phase change: Solid to liquid

Answer 25

meltiong or fusion

occurs at the melting point

Question 26

Phase change: liquid to gas

Answer 26

boiling, evaporation, or vaporization

Question 27

Phase change: gas to liguid

Answer 27

condensation

Question 28

Isothermal

Answer 28

no change in temperature thus no change in internal energy

(Q = W)

Question 29

adiabatic

Answer 29

no heat exchange

U = -W

(Q = 0)

Question 30

Isovolumetric

Answer 30

• no change in volume and is often called isochroic
• no work can be accomplised (W = PΔV)

Question 31

Isobaric

Answer 31

no change in pressure and it will remain constant

Question 32

Second law of Thermodynamics

Answer 32

states that objects that are in thermal contantact but not in thermal equilibrium will exchange heat energy until thermal equilibrium is reached (entropy)

heat will flow from hot object to cooler object

Energy spontaneously disperses from being localized to becoming spread out if not hindered from doing so

Second law states that entropy in the universe is increasing:

ΔS_universe = ΔS_system + ΔS_surroundings

Question 33

Entropy

Answer 33

• is the measure of spontaneous dispersal of energy at a specific temperature: how much energy is spread out, or how widely spread out energy becomes in a process

ΔS = Q_rev/ T

S - change in entropy

Q_rev - heat gained or loss in a reversible prosses

T - Temperature

SI - J/mol x K

Question 34

Natural Process

Answer 34

• hot object flowing energy to a cold one
• this process is also known as irreversible

Question 35

Unnatural Process

Answer 35

We would be surprised if a hot object became hotter and a cold object become colder while in thermal equilibrium

Question 36

Reversible reaction

Answer 36

• if the net entropy of the system and surroundings is equal to zero then it is a reversible reaction
• the key is to do this process very slowly
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