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Physics and Math Correct Deck > Ch. 3: Thermodynamics > Flashcards

Ch. 3: Thermodynamics Flashcards

1
Q

defn: zeroth law of thermodynamics

A

when one object is in thermal equilibrium with another object

and the second object is in thermal equilibrium with a third object

then the first and third object are also in thermal equilibrium

as such, when brought into thermal contact, no net heat will flow between these objects

the transitive property of thermal systems!!

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2
Q

what is a corollary of the zeroth law of thermodynamics?

A

heat flows between two objects not in thermal equilibrium

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3
Q

what is temperature molecularly and macroscopically?

A

MOLECULAR = temperature is proportional to the average kinetic energy of the particles that make up the substance

MACROSCOPIC = the difference in temperature between two objects that determines the direction of heat flow

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4
Q

which direction does heat move spontaneously?

A

from materials that have higher temperatures to materials that have lower temperatures (when possible)

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5
Q

defn: heat

A

the transfer of thermal energy from a hotter object with higher temperature (energy) to a colder object with lower temperature (energy)

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6
Q

defn: thermal equilibrium

A

if no net heat flows between two objects in thermal contact, we can say their temperatures are equal and they are in thermal equilibrium

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7
Q

what are the freezing and boiling points of water in Celsius and in Fahrenheit? In Kelvin?

A

FREEZING
Celsius 0, Fahrenheit 32, Kelvin 273

BOILING
Celsius 100, Fahrenheit 212, Kelvin 373

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8
Q

what is the SI unit for temperature?

A

Kelvin

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9
Q

defn: absolute zero

A

the reference point for Kelvins

the theoretical temperature at which there is no thermal energy

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10
Q

defn: third law of thermodynamics

A

the entropy of a perfectly organized crystal at absolute zero is zero

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11
Q

Kelvin and Celsius scales have different zero reference points, but what is the same?

A

the size of their units

a change of one degree Celsius equals a change of one unit Kelvin

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12
Q

implication: thermal expansion

A

a change in some physical property of one kind of matter can be correlated to certain temperature markers

once the scale has been set in reference to the decided-upon temperature markers, then the thermometer can be used to take the temperature of any other matter

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13
Q

defn + unit: coefficient of linear expansion

A

a constant that characterizes how a specific material’s length changes as the temperature changes

unit: K^-1 (or C^-1)

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14
Q

defn + relationship to linear expansion coefficient: coefficient of volumetric expansion

A

a constant that characterizes how a specific material’s volume changes as the temperature changes

three times the coefficient of linear expansion for the same material

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15
Q

defn: system

A

the portion of the universe that we are interested in observing or maniuplating

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16
Q

defn: surroundings

A

the rest of the universe (other than the system)

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17
Q

defn + ex: isolated systems

A

not capable of exchanging energy or matter with their surroundings

thus the total change in internal energy must be zero

ex: bomb calorimeter

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18
Q

defn + ex: closed systems

A

capable of exchanging energy, but not matter, with the surroundings

ex: gases in vessels with movable pistons

most of what will be on test day!

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19
Q

defn + ex: open systems

A

can exchange both matter and energy with the environment

the matter carries energy and more energy may be transferred in the form of heat or work

ex: boiling pot of water, human beings, uncontained combustion reactions

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20
Q

defn: state functions

A

thermodynamic properties that are a function of only the current equilibrium state of a system

they are independent of the path taken to get to a particular equilibrium state

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21
Q

what are the 8 state functions?

A
  1. pressure
  2. density
  3. temperature
  4. volume
  5. enthalpy
  6. internal energy
  7. Gibbs free energy
  8. entropy
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22
Q

defn: process functions (what are the two)

A

describe the path taken to get from one state to another

  1. work
  2. heat
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23
Q

defn: first law of thermodynamics

A

the change in the total internal energy of a system is equal to the amount of energy transferred in the form of heat to the system MINUS the amount of energy transferred from the system in the form of work

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24
Q

describe the sign convention and meaning for the three variables in the first law of thermodynamics

A

CHANGE IN INTERNAL ENERGY
Positive: increasing temperature
Negative: decreasing temperature

HEAT
Positive: heat flow into system
Negative: heat flows out of system

WORK
Positive: work is done by the system (expansion)
Negative: work is done on the system (compression)

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25
Q

defn: second law of thermodynamics

A

objects in thermal contact and not in thermal equilibrium will exchange heat energy such that the object with a higher temperature will give off heat energy to the object with a lower temperature until both objects have the same temperature at thermal equilibrium

26
Q

defn: heat

A

the process by which a quantity of energy is transferred between two objects as a result of the difference in temperature

27
Q

can heat ever spontaneously transfer energy from a cooler object to a warmer one?

A

if work is being done on the system

28
Q

what are the three ways by which heat can transfer energy?

A
  1. conduction
  2. convection
  3. radiation
29
Q

defn: conduction

A

the direct transfer of energy from molecule to molecule through molecular collisions

30
Q

what is something implied by the definition of conduction about the objects?

A

they must be in direct physical context

31
Q

define conduction at the atomic level

A

the particles of the hotter matter transfer some of their kinetic energy to the particles of the cooler matter through collisions between the particles of the two materials

32
Q

why are metals the best heat conductors?

A

metallic bonds contain a density of atoms embedded in a sea of electrons which facilitate rapid energy transfer

33
Q

why are gases the poorest heat conductors?

A

there is so much space between individual molecules that energy-transferring collisions occur relatively infrequently

34
Q

what is an example of heat transfer through conduction?

A

the heat that is conducted to your fingers when you touch a hot stove

35
Q

defn: convection

A

the transfer of heat by the physical motion of a fluid over a material

36
Q

why can only liquids and gases transfer heat by convection?

A

because it involves flow

37
Q

why are convection ovens more rapid cooks than radiation only ovens?

A

because heat is transferred to the food by both convection and radiation rather than jUST radiation

38
Q

convection can be used to wick heat energy away from a hot object, what is one example?

A

a running cold-water bath may be used to rapidly cool a reaction

39
Q

defn: radiation

A

the transfer of energy by electromagnetic waves

40
Q

how do radiation ovens work?

A

electrical coils or gas flames are used to heat the insulated box that forms the oven body

the hot metal box then radiates the energy through the open space of the oven, where it is absorbed by whatever food is placed inside

41
Q

what is the method of heat transfer that the sun uses to warm the Earth?

A

radiation

42
Q

what is the one type of heat transfer that can transfer energy through a vacuum?

A

radiation

43
Q

defn: specific heat (c) of a substance

A

the amount of heat energy required to raise one gram of a substance of one degree Celsius or one unit kelvin

44
Q

explain the concept behind specific heat

A

when heat energy is added to or removed from a system, the temperature of that system will change in proportion to the amount of heat transfer, unless the system is undergoing a phase change during which the temperature is constant

45
Q

does the specific heat of a substance change?

A

yes! according to its phase

46
Q

are phase changes associated with temperature changes?

A

no! phase changes occur at a constant temperature

the temperature will not begin to change until all of the substance has been converted from one phase into the other

47
Q

are phase changes related to change in kinetic or potential energy?

A

potential!

48
Q

what does increased freedom of movement allow for for water molecules?

A

a greater number of microstates

49
Q

what are the common terms used for the six phase changes?

A
  1. solid to liquid: FUSION (melting)
  2. liquid to solid: FREEZING (solidification)
  3. liquid to gas: boiling, evaporation, or vaporization
  4. gas to liquid: condensation
  5. solid to gas: sublimation
  6. gas to solid: deposition
50
Q

at what point do freezing and melting occur at? what is the corresponding heat of transformation?

A

melting point

heat of fusion

51
Q

at what point do vaporization and condensation occur at? what is the corresponding heat of transformation?

A

the boiling point

heat of vaporization

52
Q

what are the three thermodynamic processes that are considered as special cases of the first law? briefly explain them each.

A

ISOTHERMAL = constant temperature, therefore no change in internal energy

ADIABATIC = no heat exchange

ISOVOLUMETRIC = no change in volume, therefore no work is accomplished = aka ISOCHORIC

53
Q

defn: isobaric processes

A

occur at a constant pressure

54
Q

what is one implication about energy of the second law of thermodynamics

A

energy is constantly dispersed

55
Q

defn: second law of thermodynamics (energy)

A

energy spontaneously disperses from being localized to becoming spread out if it is not hindered from doing so

56
Q

defn: entropy

A

the measure of the spontaneous dispersal of energy at a specific temperature: how MUCH energy is spread out or how WIDELY spread out energy becomes in a process

57
Q

how does entropy increase or decrease when energy is distributed into or out of a system?

A

energy is distributed INTO a system at a given temp: entropy INCREASES

energy is distributed OUT of a system at a given temp: entropy DECREASES

58
Q

does the concentration of energy happen spontaneously in a closed system?

A

no! work usually has to be done to concentrate energy

59
Q

why is the second law of thermodynamics referred to as time’s arrow?

A

there is a unidirectional limitation on the movement of energy by which we recognize before and after or new and old

energy in a closed system will spontaneously spread out and entropy will increase if it is not hindered from doing so

60
Q

what is the key to a reversible reaction?

A

that is goes so slowly that the system is always in equilibrium and no energy is lost or dissipated

(no real processes are ever reversible, it can only be approximated)

61
Q

defn: reversible process

A

processes that can spontaneously reverse course

62
Q

are irreversible/reversible the same thing in chemistry and in physics?

A

no! think about it

freezing and melting of water are chemically reversible, but physics wise are irreversible (ice will not melt if it stays in the cold environment)

Physics and Math Correct Deck (12 decks)

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