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Chemistry 3321 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

What are the natural variables of entropy?

A

V and U, since its coefficients in dS = PdV + (1/T)dU are simple thermodynamic quantities

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2
Q

Sketch out a generalized phase diagram.

A

sketch https://chem.libretexts.org/Textbook_Maps/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Physical_Properties_of_Matter/States_of_Matter/Phase_Transitions/Phase_Diagrams

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3
Q

What is the triple point?

A

point on a phase diagram at which the three states of matter: gas, liquid, and solid coexist

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4
Q

What is the critical point?

A

point on a phase diagram at which the substance is indistinguishable between liquid and gaseous states

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5
Q

Sketch out the phase diagram for water and CO2.

A

sketch https://chem.libretexts.org/Textbook_Maps/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Physical_Properties_of_Matter/States_of_Matter/Phase_Transitions/Phase_Diagrams

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6
Q

State Raoult’s Law.

A

the vapor pressure of a solvent above a solution is equal to the vapor pressure of the pure solvent at the same temperature SCALED by the mole fraction of the solvent present

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7
Q

Write out the generalized, undifferentiated form of the Helmholtz free energy.

A

A = U - TS

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8
Q

The sign of the Helmholtz free energy change denotes

A

the direction of a spontaneous process in a system at constant volume and temperature (i.e. if da <= 0)

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9
Q

Sketch out a diagram of Helmholtz free energy versus time.

A

sketch Dineli’s Exam 4 Notes, page 21

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10
Q

Write out the differentiated form of the Helmholtz free energy, and show the steps to get there.

A

ΔA = ΔU - TΔS

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11
Q

Write out the generalized, undifferentiated form of the Gibbs free energy.

A

G = H - TS

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12
Q

The sign of the Gibbs free energy change denotes

A

the direction of a spontaneous process in a system at a constant pressure and temperature (i.e. if dG <= 0)

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13
Q

Sketch out a diagram of the Gibbs free energy versus time.

A

sketch Dineli’s Exam 4 Notes, page 21

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14
Q

Derive the Maxwell relation for A.

A

derive Dineli’s Exam 4 Notes, page 22

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15
Q

Write out the equation for U.

A

U = q + w

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16
Q

What are the natural variables of U?

A

S and V

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17
Q

What is the differential expression for U?

A

dU = TdS - PdV

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18
Q

What is the Maxwell relation for U?

A

(∂T/∂V)S = -(∂P/∂S)V

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19
Q

Write out the equation for H.

A

H = U + PV

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20
Q

What are the natural variables of H?

A

S and P

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21
Q

What is the differential expression for H?

A

dH = TdS + VdP

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22
Q

What is the Maxwell relation for H?

A

(∂T/∂P)S = (∂V/∂S)T

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23
Q

Write out the equation for A.

A

A = U - TS

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24
Q

What are the natural variables of A?

A

V and T

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25
Q

What is the differential expression for A?

A

dA = -PdV - SdT

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26
Q

What is the Maxwell relation for A?

A

(∂P/∂T)V = (∂S/∂V)T

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27
Q

Write out the equation for G.

A

G = H - TS

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28
Q

What are the natural variables of G?

A

P and T

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29
Q

What is the differential expression for G?

A

dG = VdP - SdT

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30
Q

What is the Maxwell relation for G?

A

(∂V/∂T)P = -(∂S/∂P)T

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31
Q

How do we calculate ΔG if we know the volume and the initial and final pressures?

A

ΔG = V*(Pf - Pi)

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32
Q

How do we calculate ΔG if we know the entropy and the initial and final temperatures?

A

ΔG = -S*(Tf - Ti)

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33
Q

What is the relationship between ∂G, ∂P, and V?

A

(∂G/∂P)T = V

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34
Q

What is the relationship between ∂G, ∂T, and S?

A

(∂G/∂T)P = -S

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35
Q

Write out the equation for the pressure dependence of G at constant T. Identify each component.

A

ΔGrxn = ΔG° + RT*lnQ — Dineli’s Exam 4 Notes, page 25

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36
Q

Write out the expression for Q.

A

write out Dineli’s Exam 4 Notes, page 25

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37
Q

Write out the formula for the temperature dependence of G at constant P. This expression leads us to what equation?

A

(G/T) = (H/T) - S, leads us to the Gibbs-Helmholtz equation

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38
Q

Write out the Gibbs-Helmholtz equation.

A

write out Dineli’s Exam 4 Notes, page 25

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39
Q

Write out the secondary version of the Gibbs-Helmholtz equation.

A

write out Dineli’s Exam 4 Notes, page 25

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40
Q

Which equation do we use when comparing the Gibbs energy of a reaction at two temperatures?

A

Gibbs-Helmholtz equation, secondary version

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41
Q

Write out the generalized ICE table for A + B —> Y + Z.

A

write out Dineli’s Exam 4 Notes, page 26

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42
Q

Write out the equation for chemical potential at constant temperature and pressure.

A

write out Dineli’s Exam 4 Notes, page 26

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43
Q

When a reaction system is in equilibrium, ΔG =

A

0

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44
Q

At equilibrium, what is true about Q and Kp?

A

Q = Kp

45
Q

Write out the equation for ΔG° given Kp.

A

ΔG° = -RT*ln(Kp)

46
Q

Write out the expression for Kp.

A

write out Dineli’s Exam 4 Notes, page 27

47
Q

How can you calculate ΔGrxn without calculating ΔG°?

A

ΔGrxn = RT*ln(Q/Kp)

48
Q

If Q < Kp, what is true about ΔG and the direction of the reaction?

A

ΔG < 0 and the reaction will shift to the right

49
Q

If Q > Kp, what is true about ΔG and the direction of the reaction?

A

ΔG > 0 and the reaction will shift to the left

50
Q

The equilibrium constant Kp is a function of

A

T and T only

51
Q

What is Le Chatelier’s principle?

A

if a chemical reaction at equilibrium is subjected to a change in conditions that displaces it from equilibrium, then the reaction adjusts toward a new equilibrium state

52
Q

Draw a graph of reaction extent versus pressure.

A

draw Dineli’s Exam 4 Notes, page 29

53
Q

What is Kc?

A

equilibrium constant with concentration terms

54
Q

Write out the expression for Kc.

A

write out Dineli’s Exam 4 Notes, page 30

55
Q

Write out the relationship between Kp and Kc. What assumptions do we make?

A

write out Dineli’s Exam 4 Notes, page 30; P° = 1 bar and c° = 1 mol/L

56
Q

Write out the equation relating Kp and two different temperatures. What is the name of this equation?

A

write out Dineli’s Exam 4 Notes, page 31; Van’t Hoff equation

57
Q

Write out the equation for the chemical potential of substance i.

A

write out Dineli’s Exam 4 Notes, page 32

58
Q

What is the physical interpretation of the partial molar Gibbs quantity?

A

a measure of how G changes when ni is changed while keeping T, P and other mole numbers fixed

59
Q

Write out the equation relating the chemical potential of a substance i and the chemical potential of its pure form. Identify each component.

A

write out Dineli’s Exam 4 Notes, page 32

60
Q

Write out the equations for G, S, and Vsoln for a liquid-liquid mixture.

A

write out Dineli’s Exam 4 Notes, page 33

61
Q

Write out the Gibbs-Duhem equation.

A

write out Dineli’s Exam 4 Notes, page 33

62
Q

Write out the Gibbs-Duhem equation for volume.

A

write out Dineli’s Exam 4 Notes, page 33

63
Q

At equilibrium, what is the relationship between the chemical potential of the solution and the chemical potential of the vapor?

A

µj(sol) = µj(vap)

64
Q

What is the formula to calculate µj(vap)? Identify each component.

A

write out Dineli’s Exam 4 Notes, page 34

65
Q

What is the formula to calculate µ*j(vap)? Identify each component.

A

write out Dineli’s Exam 4 Notes, page 34

66
Q

What is the formula to calculate µj(sol)? Identify each component.

A

write out Dineli’s Exam 4 Notes, page 35 + 36

67
Q

Write out the equation for the chemical potential of an ideal solution in the context of Raoult’s law, using activity.

A

write out Dineli’s Exam 4 Notes, page 36

68
Q

Write out the equation for the chemical potential of a non-ideal solution in the context of Raoult’s law, using activity.

A

write out Dineli’s Exam 4 Notes, page 36

69
Q

What is Dalton’s law?

A

total pressure of a system is the sum of the partial pressures exerted by each gas in the system

70
Q

What is Henry’s Law?

A

the amount of dissolved gas is proportional to its partial pressure in the gas phase

71
Q

Write out the formula for activity.

A

write out Dineli’s Exam 4 Notes, page 36

72
Q

Write out Henry’s Law for an ideal solute.

A

write out Dineli’s Exam 4 Notes, page 36

73
Q

Write out Henry’s Law for a non-ideal solute.

A

write out Dineli’s Exam 4 Notes, page 36

74
Q

What is the generalized equation for equilibrium systems consisting of gases, solids, liquids, and/or solutions? Identify each component.

A

write out Dineli’s Exam 4 Notes, page 37

75
Q

What is the standard reference state for a gas and the corresponding expression for activity?

A

chemical potential of an ideal gas at 1 bar; aj = Pj/P°

76
Q

What is the standard reference state for a solvent and the corresponding expression for activity?

A

Raoult’s Law reference/state — chemical potential of pure component j; aj = Pj/P* and aj = γ*xj

77
Q

What is the standard reference state for a solute?

A

Henry’s Law reference/state — chemical potential of an ideal solution at unit molality or unit molarity

78
Q

What are the three activity coefficient scenarios for the standard/reference state of a solute?

A

mole fraction scale; molality scale; molarity scale

79
Q

Write out the activity expressions for the mole fraction scale.

A

write out Dineli’s Exam 4 Notes, page 37

80
Q

Write out the activity expressions for the molality scale.

A

write out Dineli’s Exam 4 Notes, page 37

81
Q

Write out the activity expressions for the molarity scale.

A

write out Dineli’s Exam 4 Notes, page 37

82
Q

Write out the expression for the extended Debye-Huckel equation. Identify each component.

A

write out Dineli’s Exam 4 Notes, page 38

83
Q

Write out the expression for ionic strength. Identify each component.

A

write out Dineli’s Exam 4 Notes, page 38

84
Q

What is the relationship between ΔS-bar-trans, ΔH-bar-trans, and T?

A

write out Dineli’s Exam 4 Notes, page 38

85
Q

Write out the two variants of the Clapeyron equation.

A

write out Dineli’s Exam 4 Notes, page 38

86
Q

What is the Clapeyron equation?

A

relates the slope of the two-phase boundary line in a phase diagram

87
Q

Why can’t we use the Clapeyron equation for liquid-to-gas or solid-to-gas transitions?

A

because the molar volume of a gas varies strongly with pressure

88
Q

The Clapeyron equation is restricted to which transitions?

A

solid to liquid

89
Q

Write out the two variants of the Clausius-Clapeyron equation.

A

write out Dineli’s Exam 4 Notes, page 39

90
Q

What are the three colligative properties discussed in this unit?

A

lowering of vapor pressure; freezing point depression; boiling point elevation

91
Q

What is the simple formula for freezing point depression?

A

ΔTfus = Kf * m

92
Q

In addition to P and T, what else does G depend on?

A

the number of moles of each species in the system

93
Q

(∂G/∂P)T =

A

V

94
Q

How do we convert the activities of two ionic species into their concentrations?

A

(αx+)(αy-) = (cx+)(cy-)*(γ+/-)^2 [combined lecture notes, page 9]

95
Q

What is the phase rule?

A

degrees of freedom = 3 - (# phases in coexistence)

96
Q

The solid-gas coexistence line gives vapor pressure as a function of

A

temperature

97
Q

The solid-liquid coexistence line gives melting point as a function of

A

pressure

98
Q

(∂G/∂T)P =

A

-S

99
Q

The Clausius-Clapeyron equation is used for which transitions?

A

liquid-gas, solid-gas

100
Q

Write out the derivation for the Clausius-Clapeyron equation.

A

write out [combined lecture notes, page 12]

101
Q

Draw a graphical representation of the Clausius-Clapeyron equation. What is the slope of the line?

A

draw [combined lecture notes, page 12]; slope = -ΔHvap/R

102
Q

What is the physical interpretation of partial molar volumes?

A

if you mix two substances, the total volume of the combined mixture might change because of intermolecular forces

103
Q

Transfer dn1 moles of species 1 from solution to vapor. How does the free energy of the system change?

A

write out [combined lecture notes, page 14]

104
Q

What is the physical interpretation of Raoult’s Law?

A

surface composition is bulk composition

105
Q

What is the complex formula for freezing point depression?

A

write out [combined lecture notes, page 16]

106
Q

What is the complex formula for boiling point elevation?

A

write out [combined lecture notes, page 16]

107
Q

What is the simple formula for boiling point elevation?

A

ΔTvap = Kb * m

108
Q

What is the simple formula for osmotic pressure?

A

pi = R * T * c

Chemistry 3321 (3 decks)

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