Deck 16: Thermodynamics: Entropy, free Energy, and Equilibrium

Question 1

What is the entropy of 10⁵ molecules in 10¹⁰ boxes?

A)1)59 × 10^-21
B)3)45 × 10^-20
C)1)38 × 10^-17
D)3)18 × 10^-17

Answer 1

3)18 × 10^-17

Question 2

Entropy is a measure of

A)free energy.
B)the heat of a reaction.
C)molecular randomness.
D)the rate of a reaction.

Answer 2

molecular randomness.

Question 3

Which of the following statements is not true?

A)The reverse of a spontaneous reaction is always nonspontaneous.
B)A spontaneous process always moves toward equilibrium.
C)A nonspontaneous process cannot be caused to occur.
D)A highly spontaneous process need not occur rapidly.

Answer 3

A nonspontaneous process cannot be caused to occur.

Question 4

Which electron on an atom of copper would have the highest value of W in the Boltzmann formula?

A)3s
B)3d
C)4s
D)4p

Question 5

For which of the following will the entropy of the system increase?

A)condensation of steam
B)reaction of magnesium with oxygen to form magnesium oxide
C)reaction of nitrogen and hydrogen to form ammonia
D)sublimation of dry ice

Question 6

Which forward reaction is a nonspontaneous process?

A)the expansion of a gas into a vacuum
B)N₂(g)+ 3 H₂(g)⇌ 2 NH₃(g)if P_H₂ = P_N₂ = 1 atm,P_NH₃ = 0,and K_p = 4 × 10⁵
C)2 NH₃(g)⇌ N₂(g)+ 3 H₂(g)if P_NH₃ = 1 atm, P_H₂ = P_N₂ = 0,and K_p = 2 × 10^-6
D)None of these

Question 7

Without doing any calculations,determine whether the standard entropy change,ΔS° is positive or negative for each of the following reactions.
Reaction 1: S(s,rhombic)+ O₂(g)→ SO₂(g)
Reaction 2: 2 SO₂(g)+ O₂(g)→ 2 SO₃(g)

A)ΔS° is positive for both reactions.
B)ΔS° is positive for reaction 1 but negative for reaction 2.
C)ΔS° is positive for reaction 2 but negative for reaction 1.
D) Δs° is positive for both reactions.

Question 8

Predict the sign of ΔS of the system for both of the following.
I.2 C(graphite)+ O₂(g)→ 2 CO(g)
II.C₄H₁₀(g)→ C₄H₁₀(l)

A)ΔS should be negative for I and negative for II.
B)ΔS should be negative for I and positive for II.
C)ΔS should be positive for I and negative for II.
D)ΔS should be positive for I and positive for II.

Question 9

The reaction A(g)→ B(g)is spontaneous under standard conditions.Which of the following statements must be true?
I.The reaction B(g)→ A(g)is nonspontaneous under standard conditions.
II.A(g)will be completely converted to B(g)if sufficient time is allowed.
III.A(g)will be completely converted to B(g)rapidly.

A)none of these
B)I
C)I and II
D)I,II,and III

Question 10

Classify each of the following processes as spontaneous or nonspontaneous.
I.H₂O(l)→ H₂O(g)T = 25°C,vessel open to atmosphere with 50% relative humidity
II.H₂O(s)→ H₂O(l)T = 25°C,P = 1 atm

A)I and II are both spontaneous.
B)I is spontaneous and II is nonspontaneous.
C)I is nonspontaneous and II is spontaneous.
D)I and II are both nonspontaneous.

Question 11

Without doing any calculations,determine whether the standard entropy change,ΔS° is positive or negative for each of the following reactions.
Reaction 1: C(graphite)+ O₂(g)→ CO₂(g)
Reaction 2: 2 CO(g)+ O₂(g)→ 2 CO₂(g)

A)ΔS° is positive for both reactions.
B)ΔS° is positive for reaction 1 but negative for reaction 2.
C)ΔS° is positive for reaction 2 but negative for reaction 1.
D)ΔS° is negative for both reactions.

Question 12

Sodium reacts violently with water according to the equation:
2 Na(s)+ 2 H₂O(l)→ 2 NaOH(aq)+ H₂(g)
The resulting solution has a higher temperature than the water prior to the addition of sodium.What are the signs of ΔH° and ΔS° for this reaction?

A)ΔH° is negative and ΔS° is negative.
B)ΔH° is negative and ΔS° is positive.
C)ΔH° is positive and ΔS° is negative.
D)ΔH° is positive and ΔS° is positive.

Question 13

What is W in Boltzmann's formula,S = k ln W?

A)a fraction indicating the probability of obtaining a result
B)a random number
C)the number of ways of obtaining the state
D)the work times Avogadro's number

Question 14

What is k in Boltzmann's formula,S = k ln W?

A)the degeneracy of the state
B)the equilibrium constant for the process
C)the universal gas constant divided by Avogadro's number
D)the universal gas constant times Avogadro's number

Question 15

The brown color associated with photochemical smog is due to NO₂(g),which is involved in an equilibrium with N₂O₄(g)in the atmosphere.
2 NO₂(g)⇌ N₂O₄(g)
Predict the signs of the enthalpy and entropy change for the forward reaction.

A)The enthalpy change is negative and the entropy change is negative.
B)The enthalpy change is negative and the entropy change is positive.
C)The enthalpy change is positive and the entropy change is negative.
D)The enthalpy change is positive and the entropy change is positive.

Question 16

For which process is the sign of ΔS negative in the system?

A)2 H₂(g)+ O₂(g)→ 2 H₂O(g)
B)2 H₂O(l)+ 2 K(s)→ 2 K⁺(aq)+2 OH^-(aq)+ H₂(g)
C)H₂O(s)→ H₂O(g)
D)H₂O(l)→ H₂O(g)

Question 17

The chemical system shown below is at equilibrium.Which change in conditions will not result in a spontaneous forward reaction?
N₂(g)+ 3 H₂(g)⇌ 2 NH₃(g)K_p = 4 × 10⁵

A)adding a catalyst
B)adding more H₂
C)adding more N₂
D)reducing the volume

Question 18

An electron in an oxygen p orbital on which of the following would have the highest entropy?

A)CH₃CH₂OH
B)CH₃CH₂O^-
C)CH₃CO₂OH
D)CH₃CO₂^-

Question 19

Which of the following processes are spontaneous?
I.dissolving more solute in an unsaturated solution
II.dissolving more solute in a saturated solution
III.dissolving more solute in a supersaturated solution

A)none of these
B)I
C)I and II
D)I,II,and III

Question 20

Which of the following processes is spontaneous?

A)a mixture of two gases separating into pure compounds
B)reaction of sodium with oxygen
C)precipitation of solute from a saturated solution
D)water flowing uphill

Question 21

According to the third law of thermodynamics,

A)energy is conserved in any transformation of matter.
B)the entropy increases for any spontaneous process.
C)the entropy of a perfectly ordered,crystalline substance is zero at 0 Kelvin.
D)the entropy of the universe increases for any spontaneous process.

Question 22

Which has the lowest entropy?

A)CH₃OH(s,-25°C)
B)CH₃OH(s,-15°C)
C)CH₃OH(l,15°C)
D)CH₃OH(l,25°C)

Question 23

ΔS° = -198.7 J/K for the reaction shown below.Calculate S° for NH₃(g).
N₂(g)+ 3 H₂(g)→ 2 NH₃(g)

A)61.7 J/K∙mol
B)123.4 J/K∙mol
C)192.3 J/K∙mol
D)384.6 J/K∙mol

Question 24

Which of the following statements must be true for the entropy of a pure solid to be zero?
I.The temperature must be 0 K.
II.The solid must be crystalline,not amorphous.
III).The solid must be perfectly ordered.
IV.The solid must be an element.

A)I
B)I and II
C)I,II,and III
D)I,II,III,and IV

Question 25

What is the entropy change associated with the expansion of one mole of an ideal gas from an initial volume of V to a final volume of V of 2.50V at constant temperature?

A)ΔS = 2.50 R ln (V_f/V_i)
B)ΔS = -2.50 R ln (V_f/V_i)
C)ΔS = R ln 2.50
D)ΔS = -R ln 2.50

Question 26

The entropy change associated with the expansion of one mole of an ideal gas from an initial volume of V_i to a final volume of V_f at constant temperature is given by the equation,ΔS = R ln (V_f/V_i).What is the entropy change associated with the expansion of three moles of an ideal gas from an initial volume of V_i to a final volume of V_f at constant temperature?

A)ΔS = R ln (V_f/V_i)
B)ΔS = 3 mol × R ln (V_f/V_i)
C)ΔS = R ln (V_f × 2³/V_i)
D)ΔS = R ln (V_f × 3!/V_i)

Question 27

Which one of the following has the lowest standard molar entropy,S°,at 25°C?

A)C₈H₁₈(s)
B)C₈H₁₈(l)
C)C₁₂H₂₆(s)
D)C₁₂H₂₆(l)

Question 28

What is the sign of ΔS for each of the following processes?
I.The separation of gaseous molecules of UF₆,into ²³⁸UF₆ and ²³⁵UF₆ at
Constant temperature and pressure.
II.The dissolving of I₂(s)in CCl₄(l).

A)ΔS is negative for I and negative for II.
B)ΔS is negative for I and positive for II.
C)ΔS is positive for I and negative for II.
D)ΔS is positive for I and positive for II.

Question 29

Predict the sign of ΔS for each of the following processes,which occur at constant temperature.
I.The volume of 2.0 moles of O₂(g)increases from 44 L to 52 L.
II.The pressure of 2.0 moles of O₂(g)increases from 1.0 atm to 1.2 atm.

A)I: ΔS= negative;II: ΔS= negative
B)I: ΔS= negative;II: ΔS= positive
C)I: ΔS= positive;II: ΔS= negative
D)I: ΔS= positive;II: ΔS= positive

Question 30

Under which of the following conditions would one mole of Ne have the highest entropy,S?

A)27°C and 25 L
B)137°C and 25 L
C)27°C and 35 L
D)137°C and 35 L

Question 31

Which of the following gas molecules has the greatest standard molar entropy at 25°C?

A)C₂H₂
B)CH₂CH₂
C)CH₃CH₃
D)All have the same entropy.

Question 32

Which provides the greatest increase in entropy?

A)H₂O (s,0°C)→ H₂O (l,0°C)
B)H₂O (l,0°C)→ H₂O (l,25°C)
C)H₂O (g,0.1°C)→ H₂O (s,0.1°C)
D)H₂O (l,100°C)→ H₂O (g,100°C)

Question 33

Calculate ΔS° for the formation of one mole of solid sodium bromide from the elements at 25°C.

A)-116.7 J/K
B)-81.2 J/K
C)-40.5 J/K
D)86.8 J/K

Question 34

The Boltzmann formula is S = k ln W.A perfect crystal has a molar entropy of 0 at absolute zero because

A)W = 0.
B)W = 1.
C)W = N_A.
D)k = 1.

Question 35

Which substance has the highest standard molar entropy at 25°C?

A)C(graphite)
B)C₂H₄(g)
C)CH₃OH(l)
D)MgCO₃(s)

Question 36

Which has the highest entropy in each set?
I.H₂O(s),H₂O(l),H₂O(g)at 0.1°C,4.58 atm
II.H₂O(l)at 0°C,H₂O(l)at 25°C,H₂O(l)at 100°C (all at 1.0 atm pressure)

A)H₂O(l)in set I and H₂O(l)at 0°C in set II
B)H₂O(s)in set I and H₂O(l)at 100°C in set II
C)H₂O(g)in set I and H₂O(l)at 0°C in set II
D)H₂O(g)in set I and H₂O(l)at 100°C in set II

Question 37

Which has the highest standard molar entropy at 25°C?

A)F₂(g)
B)Cl₂(g)
C)Br₂(g)
D)I₂(g)

Question 38

Calculate ΔS° for the following reaction.
N₂(g)+ 2 O₂(g)→ 2 NO₂(g)

A)-156.5 J/K
B)-121.5 J/K
C)15.5 J/K
D)636.5 J/K

Question 39

Assume a heteronuclear diatomic molecule,AB,forms a one-dimensional crystal by lining up along the x-axis.Also assume that each molecule can only have one of six possible orientations,corresponding to atom A facing in either the positive or negative direction along the x-,y-,or z-axis.If the molecules are arranged randomly in the six directions,the molar entropy at absolute zero should be

A)R ln 6.
B)R ln 6⁶.
C)R ln 6!
D)0)

Question 40

Which has the highest standard molar entropy at 25°C?

A)Al(s)
B)Al(l)
C)Al(g)
D)All three should have a standard molar entropy of zero.

Question 41

Other than only PV work,what reaction conditions must be satisfied for the sign of ΔG to be used as a criterion for spontaneity?

A)constant volume and pressure
B)constant temperature and pressure
C)constant temperature and volume
D)constant volume only

Question 42

During perspiration,

A)the entropy of the water evaporated decreases and the entropy of the body decreases.
B)the entropy of the water evaporated decreases and the entropy of the body increases.
C)the entropy of the water evaporated increases and the entropy of the body decreases.
D)the entropy of the water evaporated increases and the entropy of the body increases.

Question 43

For the process
CaCO₃(calcite)→ CaCO₃(aragonite)ΔH° = -0.21 kJ,ΔS° = -4.2 J/K
Assuming that the surroundings can be considered a large heat reservoir at 25°C,calculate ΔS_surr and ΔS_total for the process at 25°C and 1 atm pressure.Is the process spontaneous at 25°C and 1 atm pressure?

A)ΔS_surr = 4.2 J/K,Δ_total = 0,not spontaneous
B)ΔS_surr = 0.7 J/K,ΔS_total = -3.5 J/K,not spontaneous
C)ΔS_surr = -0.7 J/K,ΔS_total = -4.9 J/K,spontaneous
D)ΔS_surr = -0.7 J/K,ΔS_total = -4.9 J/K,not spontaneous

Question 44

For a particular process ΔG is less than ΔH.Therefore

A)ΔS is positive.
B)ΔS is negative.
C)ΔS is zero.
D)ΔS is negative if ΔH is positive and ΔS is positive if ΔH is negative.

Question 45

Which of the three laws of thermodynamics provides a criterion for spontaneity?

A)the first law of thermodynamics
B)the second law of thermodynamics
C)the third law of thermodynamics
D)both the second and third laws of thermodynamics

Question 46

Consider the reaction:
N₂(g)+ 3 F₂(g)→ 2 NF₃(g)ΔH° = -249 kJ and ΔS° = -278 J/K at 25°C
Calculate ΔG° and state whether the equilibrium composition should favor reactants or products at standard conditions.

A)ΔG° = -332 kJ;the equilibrium composition should favor products.
B)ΔG° = -332 kJ;the equilibrium composition should favor reactants.
C)ΔG° = -166 kJ;the equilibrium composition should favor products.
D)ΔG° = -166 kJ;the equilibrium composition should favor reactants.

Question 47

For a particular process,ΔG = ΔH at a given temperature and pressure.Therefore,

A)ΔS is positive if ΔH is positive and negative is ΔH is negative.
B)ΔS is negative if ΔH is positive and positive if ΔH is negative.
C)ΔS is zero.
D)ΔS = ΔG/T.

Question 48

The solubility of manganese(II)fluoride in water is 6.6 g/mL at 40°C and 4.8 g/L at 100°C.Based on these data,what is the sign of ΔH° and ΔS° for the process below?
MnF₂(s)⇌ Mn²⁺(aq)+ 2 F^-(aq)

A)ΔH° is negative but the sign of ΔS° cannot be determined from this information.
B)ΔH° is negative and ΔS° is definitely negative.
C)ΔH° is positive but the sign of ΔS° cannot be determined from this information.
D)ΔH° is positive and ΔS° is definitely negative.

Question 49

For a spontaneous process

A)energy and entropy are conserved.
B)energy is conserved and the entropy of the system and surroundings increases.
C)the energy of the system and the surroundings decreases and the entropy of the system and surroundings increases.
D)both the energy and the entropy of the system and surroundings decrease.

Question 50

Which statement is true about the formation of CaCO₃(s)from CaO(s)and CO₂(g)at 1.00 atm?
CaO(s)+ CO₂(g)→ CaCO₃(s)ΔH° = -178.7 kJ and ΔS° = -150.4 J/K

A)The reaction is spontaneous at all temperatures.
B)The reaction is spontaneous at high temperatures.
C)The reaction is spontaneous at low temperatures.
D)The reaction is not spontaneous at any temperature.

Question 51

According to the second law of thermodynamics,all reactions proceed spontaneously in the direction that increases the entropy of the

A)surroundings.
B)system.
C)system - surroundings
D)system + surroundings

Question 52

For a process to be at equilibrium,it is necessary that

A)ΔS_sys = ΔS_surr.
B)ΔS_sys = -ΔS_surr.
C)ΔS_sys = 0.
D)ΔS_sys = 0 and ΔS_surr = 0.

Question 53

Why is the sign of ΔG rather than the sign of ΔS_total generally used to determine the spontaneity of a chemical reaction?

A)ΔG can be used for processes that occur under any conditions.
B)ΔG involves thermodynamic functions of the system only.
C)Free energy is easier to understand than entropy.
D)Entropy is based on probability and is therefore less reliable.

Question 54

The standard molar entropy for Br₂(g)is 245.46 J/(mol ∙ K)at 25°C.Given that ΔS° = 104.58 J/K for the dissociation of one mole of Br₂(g)into Br(g)at 25°C,find the standard molar entropy for Br(g)at 25°C.

A)70.44 J/(mol ∙ K)
B)140.08 J/(mol ∙ K)
C)175.02 J/(mol ∙ K)
D)350.04 J/(mol ∙ K)

Question 55

For bromine,ΔH°vap = 30.91 kJ/mol and ΔS°vap = 93.23 JK^-1mol^-1 at 25°C.What is the normal boiling point for bromine?

A)25°C
B)58°C
C)124°C
D)332°C

Question 56

At constant pressure and temperature,which statement is true?

A)All reactions for which ΔH < 0 are spontaneous.
B)All reactions for which ΔS < 0 are spontaneous.
C)All reactions for which ΔG < 0 are spontaneous.
D)All reactions for which K < 1 are spontaneous.

Question 57

At 25°C,ΔH° = 1.895 kJ and ΔS° = -3.363 J/K for the transition
C(graphite)→ C(diamond)
Based on these data,

A)graphite cannot be converted to diamond at 1 atm pressure.
B)diamond is more stable than graphite at all temperatures at 1 atm.
C)diamond is more stable than graphite below 290°C and graphite is more stable than diamond above 290°C.
D)graphite is more stable than diamond below 290°C and diamond is more stable than graphite above 290°C.

Question 58

For the reaction 3 C₂H₂(g)→ C₆H₆(l)at 25°C,the standard enthalpy change is -631 kJ and the standard entropy change is -430 J/K.Calculate the standard free energy change at 25°C.

A)948 kJ
B)-503 kJ
C)-618 kJ
D)-1061 kJ

Question 59

Which of the following is a criterion for spontaneity that holds for any process?

A)ΔG < 0
B)ΔG > 0
C)ΔS_total < 0
D)ΔS_total > 0

Question 60

A hot penny is dropped into cold water inside a polystyrene foam cup.Assuming negligible heat loss to the atmosphere and the cup,

A)the decrease in entropy of the penny is equal to the increase in entropy of the water. ∣ ΔS_penny ∣ = ∣ ΔS_water ∣
B)the decrease in entropy of the penny is less than the increase in entropy of the water. ∣ ΔS_penny ∣ < ∣ ΔS_water ∣
C)the decrease in entropy of the penny is more than the increase in entropy of the water. ∣ ΔS_penny ∣ > ∣ ΔS_water ∣
D)the entropy of both the penny and the water increases.

Question 61

For any thermodynamic function Y,ΔY° for a reaction refers to the change in Y for the process in which

A)the mixed reactants at 1 atm go to equilibrium at 1 atm.
B)the separate reactants at 1 atm go to equilibrium at 1 atm.
C)the separate reactants in their standard states are completely converted to separate products in their standard states.
D)the spontaneous reaction occurs.

Question 62

At high temperatures boron carbide vaporizes according to the equation
B₄C(s)⇌ 4 B(g)+ C(s)
Which equation describes the relationship between ΔG° and ΔG for this reaction?

A)ΔG = ΔG° + R T ln (p_B ∙ [C]/[B₄C])
B)ΔG = ΔG° + R T ln p_B
C)ΔG = ΔG° + 4 R T ln p_B
D)ΔG = ΔG° - 4 R T ln p_B

Question 63

For a reaction at constant temperature,as Q increases

A)ΔG and ΔG° increase.
B)ΔG and ΔG° decrease.
C)ΔG increases,but ΔG° remains constant.
D)ΔG decreases,but ΔG° remains constant.

Question 64

For the evaporation of water during perspiration on a hot,dry day,

A)ΔH is positive and TΔS = ΔH.
B)ΔH is positive and TΔS > ΔH.
C)ΔH is positive and TΔS < ΔH.
D)ΔH is negative and TΔS is positive.

Question 65

The signs of ΔG,ΔH,and ΔS at 25°C are shown below for three reactions.
Which reaction could go in the reverse direction at high temperature?

A)I
B)II
C)III
D)I and II

Question 66

A reaction has ΔH° = 61.9 kJ/mol and ΔS° = 405.4 J/K.Is this reaction spontaneous or nonspontaneous? At what temperature (if any)can the spontaneity be reversed?

A)nonspontaneous,can be made spontaneous at 153 K
B)nonspontaneous,cannot be made spontaneous at any temperature
C)spontaneous,can be made nonspontaneous at 153 K
D)spontaneous,cannot be made nonspontaneous at any temperature

Question 67

Which is the lowest at 25°C?

A)ΔG°_f for H₂O (s)
B)ΔG°_f for H₂O (l)
C)ΔG°_f for H₂O (g)
D)1/2ΔG°_f for O₂ (g)plus ΔG°_f for H₂O (g)

Question 68

At 25°C,?G°_f is -620 kJ/mol for SiCl₄(g)and -592 kJ/mol for MgCl₂(s).Calculate ?G° for the reaction,SiCl₄(g)+ 2 MG(s) $\rarr$ 2 MgCl₂(s)+ Si(s)and determine if the reaction is spontaneous at 25°C if the pressure of SiCl₄(g)is 1 atm.

A)?G° = 28 kJ;the process is spontaneous.
B)?G° = 28 kJ;the process is nonspontaneous.
C)?G° = -564 kJ;the process is spontaneous.
D)?G° = -564 kJ;the process is nonspontaneous.

Question 69

In general,as a reaction goes to equilibrium

A)ΔG decreases.
B)ΔG°_f decreases.
C)ΔG goes to zero.
D)ΔG° decreases.

Question 70

Which of the following is true?

A)As a reaction at constant temperature and pressure goes to equilibrium,|ΔG| decreases.
B)The larger ΔG°,the faster the reaction.
C)The standard state for solutes is the pure solute at 1 atm.
D)When a reaction reaches equilibrium,ΔG° = 0.

Question 71

Which of the following are unstable with respect to their constituent elements at 25°C?

A)C₈H₁₈(l),CH₃OH(l)
B)C₈H₁₈(l),C₂H₂(g)
C)C₂H₂(g)
D)CH₃OH(l)

Question 72

Calculate the standard free energy change at 25°C for the reaction
2 NO(g)+ O₂(g)→ 2 NO₂(g).

A)-4.7 kJ
B)-72.6 kJ
C)-157.8 kJ
D)-532.6 kJ

Question 73

Which of the following is zero at 25°C?

A)ΔG°_f for N₂(g)
B)ΔG°_f for H₂O (l)
C)S° for N₂ (g)
D)S° for H₂O (l)

Question 74

For the reaction below ΔG° = +33.0 kJ,ΔH° = +92.2 kJ,and ΔS° = +198.7 J/K.Estimate the temperature at which this reaction becomes spontaneous.
2 NH₃(g)→ N₂(g)+ 3 H₂(g)

A)0)464 K
B)166 K
C)298 K
D)464 K

Question 75

Calculate the standard free energy for the reaction given.
2 CH₃OH(l)+ 3 O₂(g)→ 2 CO₂(g)+ 4 H₂O(l)

A)-465.2 kJ
B)-797.8 kJ
C)-1404.8 kJ
D)-2069.8 kJ

Question 76

At 2600 K,ΔG° = 775 kJ for the vaporization of boron carbide:
B₄C(s)⇌ 4 B(g)+ C(s)
Find ΔG and determine if the process is spontaneous if the reaction vessel contains 4.00 mol B₄C(s),0.400 mol of C(s),and B(g)at a partial pressure of 1.0 × 10^-5 atm.At this temperature,R T = 21.6 kJ.

A)ΔG = -270 kJ;spontaneous.
B)ΔG = -270 kJ;nonspontaneous.
C)ΔG = -220 kJ;spontaneous.
D)ΔG = -220 kJ;nonspontaneous.

Question 77

A reaction has ΔH° = -60.9 kJ/mol and ΔS° = 266.6 J/K.Is this reaction spontaneous or nonspontaneous? At what temperature (if any)can the spontaneity be reversed?

A)nonspontaneous,can be made spontaneous at 228 K
B)nonspontaneous,cannot be made spontaneous at any temperature
C)spontaneous,can be made nonspontaneous at 228 K
D)spontaneous,cannot be made nonspontaneous at any temperature

Question 78

At 25°C,ΔG° = -198 kJ for the reaction,NO(g)+ O₃(g)⇌ NO₂(g)+ O₂(g).
Calculate ΔG under the following conditions:

A)-159 kJ
B)-167 kJ
C)-198 kJ
D)-236 kJ

Question 79

A positive value of ΔG°_f for a solid compound at 25°C means the

A)compound cannot exist at 25°C and 1 atm.
B)compound must be a liquid or a gas at 25°C and 1 atm.
C)process of forming the compound from the elements is exothermic.
D)process of forming the compound from the stable elements at 25°C and 1 atm is nonspontaneous.

Question 80

Which statement is true concerning the standard states of F₂(g)and C₆H₁₂O₆(aq)?

A)The standard state for F₂(g)is the pure gas at 1 atm and for C₆H₁₂O₆(aq)is the pure solid at 1 atm.
B)The standard state for F₂(g)is the pure gas at 1 mol/L and for C₆H₁₂O₆(aq)is the pure solid at 1 atm.
C)The standard state for F₂(g)is the pure gas at 1 atm and for C₆H₁₂O₆(aq)is the solution at a concentration of 1 mol/L.
D)The standard state for F₂(g)is the pure gas at 1 mol/L and for C₆H₁₂O₆(aq)is the solution at a concentration of 1 mol/L.