Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MCAT Chemistry by me > Thermodynamics > Flashcards

Thermodynamics Flashcards

You may prefer our related Brainscape-certified flashcards:
MCAT flashcards Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

What is temperature on a molecular scale

A

total of vibrational, rotational, and translational energies

amount of molecular movement; thermal energy per mole of molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

In gas and liquid, what is the main determinant of temperature out of the three energies that contribute to thermal energy?

A

translational energy in 3D

tarnslational energy (moving the center of mass) depends on degrees of freedom or modes (3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the average kinetic energy per mole of molecules

A

3/2 * RT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does increase in temperature affect the volume for gases of different pressures?

In a Volume vs. Temperature graph, where do the lines of different pressures of gas intersect?

At 1 atm at 273K (0C), what is the molar volume of 1 mole of gas molecules?

A

directly proportional - positive linear relationship for all gases at different pressures but with different slopes

gases at different pressures will extrapolate and intersect at absolute 0 K

22.4 L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is pressure in terms of force and kinetic energy?

Specifically, what kind of kinetic energy is pressure?

A

Force over an area

Random translational kinetic energy of a group of molecules per volume occupied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How do you define an internal energy and what are the two component that make up the internal energy?

A

sum of “kinetic and internal energy in a system - collective energy within a system, not the motion or position of the system

Kinetic energy portion: rotational, vibrational, translational

Potential energy portion: electronic (potential electrical energy created b the attractions between electrons and their nuclei), intermolecular potential energy, rest mass energ (E=mc^2).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What component of internal energy is the only thing that can change in an ideal gas? what about for a real gas?

A

Translational energy; therefore, temperature is the only component of internal energy that can change

for a real gas, any change in the components of internal energy can cause a change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is heat

A

Random collisions between molecules of two systems where energy is transferred from higher to lower energy molecules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what does it mean to reach equilibrium for two systems in terms of molecular collisions

A

there are still collisions happening but there is no transfer of energy. the two systems have the same temperature and kinetic energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is conduction

A

thermal energy transfer via molecular collisions (actual physical conditions)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what does thermal conductivity of conduction depend on

A

it depends mainly on composition and to a less degree on temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is convection?

what drives the movement of fluid and in what direction does it flow?

what is an example

A

transfer of thermal energy via a fluid

different in pressure or density drive the warm fluid in the direction of cool fluid

circular current of air carrying the heat (ocean and air currents)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is radiation

what objects radiate heat?

A

thermal energy transfer via electromagnetic waves

all objects with a temperature radiate heat (above 0 K)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is power in terms of radiation

A

rate of heat transfer via radiation or electromagnetic waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what affects the rate of thermal energy transfer via radiation?

A

it depends on fraction of heat absorbed, surface area, and different in temperature

mainly on temperature difference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

in radiation, what does it mean when an objects has an emissivity of 1?

A

absorbs everything, appear black

black body radiator is only in theory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the only transfer of heat that can occur through a vacuum?

A

radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what does it mean when a system does work?

what does it mean on a molecular level?

A

the system changes in size or shape while position remains the same - there must be a change in volume so it is said to do PV work

on a molecular level, it is a directional collision of molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the capacity to do work?

what about unconstrained system with infinite volume?

A

arises from constraints of molecules like piston

unconstrained system like ideal gas with infinite volume can do no work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how to define whether or not the energy transfer is heat or work

A

depends on the effect of the surrounding

random collisions on the surrounding is heat

ordered molecular collisions on the surrounding is work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Is enthalpy conserved

A

nope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is enthalpy

A

theoretical concept that calculates heat transferred assuming that there is no non-PV work done under constant pressure.

∆H = ∆U + P∆V 
∆H = (non-PV work - P∆V + q) + P∆V
∆H = non-PV work +q

when there is constant pressure and assuming no non-PV work is done: ∆H = q (constant pressure, closed system at rest)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

for an ideal gas, what does the enthalpy depend on

A

enthalpy depends only on temperature for an ideal gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

types of work that a system at rest can do

A

PV work and non-PV work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is a non-PV work

A

electrical work, twisting work, polarization work, and etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

is work a state function

A

work is not a state function and depends on the thermodynamic path taken

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

sign conventions for work:

work done by the system
work done on the system

A

work done by the system -ve

work done on the system +ve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what is electronic energy

A

the attractive energy between the nucleus and electrons as a part of internal energy

explains the phenomenon in electron absorption and emission.

greatest change that occurs when there is a chemical reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is intermolecular potential energy

A

energy created by intermolecular forces between molecular dipoles

becomes significant at high pressure for gases. Makes up a substantial portion of internal energy in liquids and solids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what is rest mass energy

A

E = mc^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

∆G at equilibrium

A

0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

∆S of the universe at equilibrium

A

0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

is gibbs energy conserved?

A

not conserved and extensive property

34
Q

what does gibbs free energy represent

What is gibbs free energy useful for analyzing?

A

maximum non-PV work available from or free for a reaction. Maximum amount of energy released by a process occurring at constant temperature and pressure that is available to perform useful work.

Contracting muscles, transmitting nerves, and batteries do only non-PV Work so Gibbs energy is useful for analyzing these systems

35
Q

what is the standard state condition for temperature, pressure, and molarity for aquesous solutions at which enthalpies and gibbs free energy are defined?

A

25C (room temperature) at 1 atm or 1 barr

1 M for aqueous solutions

36
Q

what is Gibbs free energy?

A

free energy to do non-PV work like electronic work

H - TS

37
Q

what does it mean when the reaction is spontaneous?

A

reaction starts immediately

38
Q

does molality change with temperature?

does molarity change with temperature?

A

Molality does not change with temperature because it measures moles per kg

molarity does change with temperature because change in temperature causes a change in volume

39
Q

what is a colligative property

A

property that depends on the amount, not the kind

40
Q

way to increase heat transfer through conduction

A

greater temperature difference, shorter, and fatter

T^4

41
Q

way to increase heat transfer through radiation

A

increase surface area and the temperature difference

T^4

42
Q

can thermal energy be completely converted to work in cyclical process?

A

thermal energy cannot be completely converted to work. it is the second law of thermodynamics

43
Q

can 0 K exist?

A

0K cannot theoretically exist

44
Q

equation for enthapy

equation for enthalp with no change in volume

what is the enthalpy generally for liquids and solids?

A

internal energy + PV work

with no change in volume, it is just change in internal energy

for liquids and solids, it is generally equal to heat under constant pressure

45
Q

enthalpy of pure elements at standard condition

A

at standard condition of 25C, 1 atm, and 1 M, the enthalpies of pure elements are 0

46
Q

What is the main contributor of change in kinetic energy in a gas?

A

translational energy

47
Q

What are examples of two path way dependent functions?

A

work and heat?

48
Q

What are the 7 thermodynamic state functions?

A 
Internal energy, U
Temperature, T
Pressure, P
Volume, V
Enthalpy, H
Entropy, S
Gibbs Free Energy
49
Q

If you know three macroscopic properties of a one-component system in equilibrium and at least _____ of them is extensive, you can find all of the other properties

A

extensive

50
Q

What is electronic potential energy?

A

The potential energy created by the attractions between electrons and their nuclei

51
Q

In a chemical reaction, changing what type of potential energy accounts for the greatest change in internal energy?

What can you say if this energy remains constant?

A

Changing the electronic potential energy accounts for the greatest change in internal energy

If electronic potential energy remains constant, we can say that there is no chemical reaction.

52
Q

What is intermolecular potential energy?

For which phases is the intermolecular potential energy make a significant contribution?

For gases, when can intermolecular potential energy make a significant contribution?

A

Potential energy created by intermolecular forces between molecular dipoles.

Intermolecular potential energy is significant for solids and liquids. But it can be for gas at higher pressure when the gas molecules are close together where attractive forces become significant.

53
Q

Is Internal energy a state function?

A

YES

54
Q

Is Gibbs free energy extensive or intensive property?

A

Extensive

55
Q

The standard free energy change for a reaction from the equilibrium constant Keq

A

-RT ln Keq

56
Q

Free energy change reflective of where it is in the path to equilibrium

A

RT (ln Q/ Keq)

57
Q

Change in entropy for a reversible reaction

A

Qrev/T

When energy is distributed into a system, the entropy increases. When energy is distributed out of a system at a given temperature, the entropy decreases.

58
Q

Cp vs. Cv

A

Cp > Cv

59
Q

Specific heat

A

Amount of heat required to raised the temperature of 1 g of substance by 1 C or 1 K.

60
Q

Specific heat vs. heat capacity

A

Specific heat - cal/g*K

Heat capacity - cal/K (specific heat times mass)

61
Q

Example of constant pressure calorimeter

Example of a constant volume calorimeter

A

Coffee cup

Bomb calorimeter - no work is done (constant V). Also Adiabatic because no heat is exchanged wrt outside the bomb calorimeter. Heat only exchanged between the vessel and the surrounding water

62
Q

Isothermal process

A

Constant temperature

Steep hyperbolic curve placed above Adiabatic process on PV graph.
No change in internal energy means Q absorbed = W done by the system.

63
Q

Adiabatic process

A

Constant heat

Work only.
Hyperbolic curve placed lower than the isothermal process on the PV Graph

64
Q

Isobaric process

A

Constant pressure

Nice rectangle to find a curve on PV graph
Q = enthalpy

65
Q

Zeroth Law of Thermodynamics

A

Q system = -Q sure

66
Q

Second law of thermodynamics

A

Strive toward thermal equilibrium

Change in entropy = Qrev/T at a specific temperature

Objects in thermal contact (but not in equilibrium) will exchange heat energy such that object with higher heat energy will give off heat until the objects are in thermal equilibrium

67
Q

Reversible reaction

A

A slow process where the system is always in equilibrium so no energy is lost or dissipated

Every natural process is irreversible but certain equilibrium processes such as phase changes can be treated as reversible

68
Q

In a reversible reaction, what is change in entropy of surrounding plus the change in entropy of the system?

A

ZERO

69
Q

Internal Energy Equations

A

3/2 (P∆V) = 3/2 nkT = 3/2 NRT

70
Q

Molar Cp - Molar Cv = ?

A

R

71
Q

Molar Cv = ?

Molar Cp = ?

A

Molar Cv = 3/2

Molar Cp = 5/2

72
Q

The main type of internal energy for a monatomic gas

A

Translational kinetic energy

Monoatomic gases do not have rotational or vibrational energies.

Vibrational energy is from vibrations of atoms WITHIN a MOLECULE.
Rotational energy: rotation around a center of mass where one point is fixed and the other atom rotates around this mass

73
Q

What can you say about a reaction if there is no change in electronic potential energy?

A

That no “chemical” reaction has taken place. A physical reaction may have taken place but not change in the bonding.

74
Q

When is the intermolecular potential energy significant?

A

It’s significant when the molecules are close together as in solids and liquids under high pressure and low temperature for gases

75
Q

For an ideal gas, what component of internal energy can change? What does it imply?

A

Translational energy, meaning that an ideal gas is independent of volume and dependent only on temperature

76
Q

Capacity to do work rises from ______

A

The constraints of molecules so participles in an infinite volume of space can do no work

77
Q

Enthalpy and internal energy changes ONLY with ________

A

Temperature

78
Q

Standard heat of combustion

A

Enthalpy change associated with the combustion of fuel

79
Q

Thermal Expansion for Solids

A

∆L = å L∆T

80
Q

Thermal Expansion for liquids

A

∆V = ß V∆T

81
Q

Specific heat of water

A

1 cal/g*K

4.18 J/g*K

82
Q

1 Cal = ____ cal = _____ kJ

A

1 Cal = 1000 cal = 4.18 kJ

MCAT Chemistry by me (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions