Deck 17: Spontaneity, entropy, and Free Energy

Question 1

Consider the following processes:
I.condensation of a liquid
IIincreasing the volume of 1.0 mol of an ideal gas at constant temperature
III.dissolving sugar in water
IV.heating 1.0 mol of an ideal gas at constant volume
For how many of these is $\Delta$ S positive?

A)0
B)1
C)2
D)3
E)4

Answer 1

3

Question 2

Which of the following statements is true?

A)The total energy and entropy of the universe are both increasing.
B)The total energy of the universe is increasing,but the entropy is constant.
C)The total energy of the universe increases,while the entropy decreases.
D)The total energy of the universe is constant,but the entropy is increasing.
E)None of these.

Answer 2

The total energy of the universe is constant,but the entropy is increasing.

Question 3

Which of the following shows a decrease in entropy?

A)precipitation
B)gaseous reactants forming a liquid
C)a burning piece of wood
D)melting ice
E)two of these

Answer 3

two of these

Question 4

Assume that the enthalpy of fusion of ice is 6020 J/mol and does not vary appreciably over the temperature range 270-290 K.If one mole of ice at 0°C is melted by heat supplied from surroundings at 276 K,what is the entropy change in the surroundings,in J/K?

A)22.1
B)21.8
C)0.0
D)-21.8
E)-22.1

Question 5

Which of the following result(s)in an increase in the entropy of the system?
I.
II.
Br₂(g) $\to$ Br₂(l)
III.
NaBr(s) $\to$ Na⁺(aq)+ Br^-(aq)
IV.
O₂(298 K) $\to$ O₂(373 K)
V.
NH₃(1 atm,298 K) $\to$ NH₃(3 atm,298 K)

A)I
B)II,V
C)I,III,IV
D)I,II,III,IV
E)I,II,III,V

Question 6

The heat of vaporization for 1.0 mole of water at 100.°C and 1.0 atm is 40.56 kJ/mol.Calculate $\Delta$ S for the process H₂O(l) $\to$ H₂O(g)at 100.°C.

A)109 J/K mol
B)-109 J/K mol
C)406 J/K mol
D)-406 J/K mol
E)none of these

Question 7

A two-bulbed flask contains 5 particles.What is the probability of finding all 5 particles on the left side?

A)2.50%
B)2.24%
C)3.13%
D)0.20%
E)6.25%

Question 8

Ten identical coins are shaken vigorously in a cup and then poured out onto a table top.Which of the following distributions has the highest probability of occurrence? (T = Tails,H = Heads)

A)T₁₀H₀
B)T₈H₂
C)T₇H₃
D)T₅H₅
E)T₄H₆

Question 9

A change of state that occurs in a system is accompanied by 52.3 kJ of heat,which is transferred to the surroundings at a constant pressure and a constant temperature of 300.K.For this process $\Delta$ S_surr is:

A)52.3 kJ/K
B)-52.3 kJ/K
C)-174 J/K
D)174 J/K
E)248 kJ/K

Question 10

A 100-mL sample of water is placed in a coffee cup calorimeter.When 1.0 g of an ionic solid is added,the temperature decreases from 21.5°C to 20.8°C as the solid dissolves.For the dissolving of the solid

A)( $\Delta$ H < 0)
B)( $\Delta$ S_univ > 0)
C)( $\Delta$ S_sys< 0)
D)( $\Delta$ S_surr > 0)
E)none of these

Question 11

If two pyramid-shaped dice (with numbers 1 through 4 on the sides)were tossed,which outcome has the highest entropy?

A)The sum of the dice is 3.
B)The sum of the dice is 4.
C)The sum of the dice is 5.
D)The sum of the dice is 6.
E)The sum of the dice is 7.

Question 12

At 1 atm,liquid water is heated above 100°C.

- $\Delta$ S_surr for this process is

A)greater than zero
B)less than zero
C)equal to zero
D)more information needed to answer this question
E)none of these (A-D)

Question 13

Which of the following is true for exothermic processes?

A)( $\Delta$ S_surr < 0)
B)( $\Delta$ S_surr) = - $\Delta$ H/T
C)( $\Delta$ S_surr = 0)
D)( $\Delta$ S_surr > 0)
E)two of these

Question 14

$\Delta$ S_surr is _______ for exothermic reactions and ______ for endothermic reactions.

A)favorable,unfavorable
B)unfavorable,favorable
C)favorable,favorable
D)unfavorable,unfavorable
E)cannot tell

Question 15

The enthalpy of vaporization of ammonia is 23.35 kJ/mol at its boiling point (-33.4°C).Calculate the value of $\Delta$ S_surr when 1.00 mole of ammonia is vaporized at -33.4°C and 1.00 atm.

A)0
B)-6.99 $\times$ 10² J/K mol
C)9.74 $\times$ 10¹ J/K mol
D)-9.74 $\times$ 10¹ J/K mol
E)6.99 $\times$ 10² J/K mol

Question 16

At 1 atm,liquid water is heated above 100°C.

- $\Delta$ S_sys for this process is

A)greater than zero
B)less than zero
C)equal to zero
D)more information needed to answer this question
E)none of these (A-D)

Question 17

For which process is $\Delta$ S negative?

A)evaporation of 1 mol of CCl₄(l)
B)mixing 5 mL ethanol with 25 mL water
C)compressing 1 mol Ne at constant temperature from 1.5 L to 0.5 L
D)raising the temperature of 100 g Cu from 275 K to 295 K
E)grinding a large crystal of KCl to powder

Question 18

If the change in entropy of the surroundings for a process at 431 K and constant pressure is -326 J/K,what is the heat flow absorbed by for the system?

A)326 kJ
B)1.32 kJ
C)-141 kJ
D)105 kJ
E)141 kJ

Question 19

The second law of thermodynamics states that:

A)The entropy of a perfect crystal is zero at 0 K.
B)The entropy of the universe is constant.
C)The energy of the universe is increasing.
D)The entropy of the universe is increasing.
E)The energy of the universe is constant.

Question 20

A chemical reaction is most likely to be spontaneous if it is accompanied by

A)increasing energy and increasing entropy
B)lowering energy and increasing entropy
C)increasing energy and decreasing entropy
D)lowering energy and decreasing entropy
E)none of these (A-D)

Question 21

Substance X has a heat of vaporization of 58.4 kJ/mol at its normal boiling point (423°C).For the process X(l) $\to$ X(g)at 1 atm and 423°C calculate the value of $\Delta$ S_surr.

A)0
B)83.9 J/K mol
C)138 J/K mol
D)-83.9 J/K mol
E)-138 J/K mol

Question 22

Given that $\Delta$ H_vap is 58.2 kJ/mol,and the boiling point is 83.4°C,1 atm,if one mole of this substance is vaporized at 1 atm,calculate $\Delta$ S_surr.

A)-163 J/K mol
B)163 J/K mol
C)698 J/K mol
D)-698 J/K mol
E)0

Question 23

Substance X has a heat of vaporization of 55.9 kJ/mol at its normal boiling point (423°C).For the process X(l) $\to$ X(g)at 1 atm and 423°C calculate the value of $\Delta$ S_univ.

A)0
B)80.3 J/K mol
C)132 J/K mol
D)-80.3 J/K mol
E)-132 J/K mol

Question 24

At 1 atm,liquid water is heated above 100°C.

- $\Delta$ S_univ for this process is

A)greater than zero
B)less than zero
C)equal to zero
D)more information needed to answer this question
E)none of these (A-D)

Question 25

Substance X has a heat of vaporization of 64.4 kJ/mol at its normal boiling point (423°C).For the process X(l) $\to$ X(g)at 1 atm and 423°C calculate the value of $\Delta$ G.

A)0 J
B)92.5 J
C)152 J
D)-92.5 J
E)-152 J

Question 26

The enthalpy of vaporization of ammonia is 23.35 kJ/mol at its boiling point (-33.4°C).Calculate the value of $\Delta$ S when 1.00 mole of ammonia is vaporized at -33.4°C and 1.00 atm.

A)0
B)-6.99 $\times$ 10² J/K mol
C)9.74 $\times$ 10¹ J/K mol
D)-9.74 $\times$ 10¹ J/K mol
E)6.99 $\times$ 10² J/K mol

Question 27

For the vaporization of a liquid at a given pressure:

A)( $\Delta$ G) is positive at all temperatures.
B)( $\Delta$ G) is negative at all temperatures.
C)( $\Delta$ G) is positive at low temperatures,but negative at high temperatures (and zero at some temperature).
D)( $\Delta$ G) is negative at low temperatures,but positive at high temperatures (and zero at some temperature).
E)None of these (A-D).

Question 28

$\Delta$ S is _______ for exothermic reactions and ______ for endothermic reactions.

A)favorable,unfavorable
B)unfavorable,favorable
C)favorable,favorable
D)unfavorable,unfavorable
E)cannot tell

Question 29

For any given process, $\Delta$ S_surr and $\Delta$ S_sys have opposite signs.

Question 30

Given that $\Delta$ H_vap is 60.3 kJ/mol,and the boiling point is 83.4°C,1 atm,if one mole of this substance is vaporized at 1 atm,calculate $\Delta$ S.

A)-169 J/K mol
B)169 J/K mol
C)723 J/K mol
D)-723 J/K mol
E)0

Question 31

For the process CHCl₃(s) $\to$ CHCl₃(l), $\Delta$ H° = 9.19 kJ/mol and $\Delta$ S° = 43.9 J/mol/K.What is the melting point of chloroform?

A)-64 °C
B)209 °C
C)130 °C
D)64 °C
E)-130 °C

Question 32

Consider two perfectly insulated vessels.Vessel #1 initially contains an ice cube at 0°C and water at 0°C.Vessel #2 initially contains an ice cube at 0°C and a saltwater solution at 0°C.In each vessel,consider the "system" to be the ice,and the "surroundings" to be the liquid.

-Determine the sign of $\Delta$ S_sys, $\Delta$ S_surr,and $\Delta$ S_univ for the contents of Vessel #1.

A)0 0 0
B)+ - 0
C)+ + +
D)+ - +
E)+ 0 +

Question 33

$\Delta$ H° is zero for a chemical reaction at constant temperature.

Question 34

Consider two perfectly insulated vessels.Vessel #1 initially contains an ice cube at 0°C and water at 0°C.Vessel #2 initially contains an ice cube at 0°C and a saltwater solution at 0°C.In each vessel,consider the "system" to be the ice,and the "surroundings" to be the liquid.

-Determine the sign of $\Delta$ S_sys, $\Delta$ S_surr,and $\Delta$ S_univ for the system (ice/saltwater)in Vessel #2.

A)0 0 0
B)+ - 0
C)+ + +
D)+ - +
E)+ 0 +

Question 35

The melting point of water is 0°C at 1 atm pressure because under these conditions:

A)( $\Delta$ S) for the process H₂O(s) $\to$ H₂O(l)is positive.
B)( $\Delta$ S) and $\Delta$ S_surr for the process H₂O(s) $\to$ H₂O(l)are both positive.
C)( $\Delta$ S) and $\Delta$ S_surr for the process H₂O(s) $\to$ H₂O(l)are equal in magnitude and opposite in sign.
D)( $\Delta$ G) is positive for the process H₂O(s) $\to$ H₂O(l).
E)None of these is correct.

Question 36

Which of the following is true?

A)By spontaneous we mean that the reaction or process will always proceed to the right (as written)even if very slowly.Increasing the temperature may speed up the reaction,but it does not affect the spontaneity of the reaction.
B)By spontaneous we mean that the reaction or process will always proceed to the left (as written)even if very slowly.Increasing the temperature may speed up the reaction,but it does not affect the spontaneity of the reaction.
C)By spontaneous we mean that the reaction or process will always proceed to the left (as written)even if very slowly.Increasing the temperature may speed up the reaction and it generally affects the spontaneity of the reaction.
D)By spontaneous we mean that the reaction or process will always proceed to the right (as written)even if very slowly.Increasing the temperature may speed up the reaction,and it generally affects the spontaneity of the reaction.
E)None of the above is true.

Question 37

Substance X has a heat of vaporization of 47.1 kJ/mol at its normal boiling point (423°C).For the process X(l) $\to$ X(g)at 1 atm and 423°C calculate the value of $\Delta$ S.

A)0
B)67.7 J/K mol
C)111 J/K mol
D)-67.7 J/K mol
E)-111 J/K mol

Question 38

Which of the following statements is always true for a spontaneous process?
I. $\Delta$ Ssys > 0
II. $\Delta$ Ssurr > 0
III. $\Delta$ Suniv > 0
IV. $\Delta$ Gsys > 0

A)I
B)III
C)IV
D)I and III
E)III and IV

Question 39

If $\Delta$ S_surr = - $\Delta$ S_sys,the process is at equilibrium.

Question 40

As long as the disorder of the surroundings is increasing,a process will be spontaneous.

Question 41

For a spontaneous exothermic process,which of the following must be true?

A)( $\Delta$ G) must be positive.
B)( $\Delta$ S) must be positive.
C)( $\Delta$ S) must be negative.
D)Two of the above must be true.
E)None of the above (A-C)must be true.

Question 42

What must be true about $\Delta$ G for this reaction?

A)( $\Delta$ G = $\Delta$ H
B)( $\Delta$ G = 0)
C)( $\Delta$ G > 0)
D)( $\Delta$ G < 0)
E)( $\Delta$ G) = $\Delta$ S_univ

Question 43

As O₂(l)is cooled at 1 atm,it freezes at 54.5 K to form Solid I.At a lower temperature,Solid I rearranges to Solid II,which has a different crystal structure.Thermal measurements show that $\Delta$ H for the I $\to$ II phase transition is -743.07 J/mol,and $\Delta$ S for the same transition is -17.0 J/K mol.At what temperature are Solids I and II in equilibrium?

A)13.6 K
B)43.7 K
C)19.8 K
D)98.2 K
E)They can never be in equilibrium because they are both solids.

Question 44

When ignited,solid ammonium dichromate decomposes in a fiery display.This is the reaction for a "volcano" demonstration.The decomposition produces nitrogen gas,water vapor,and chromium(III)oxide.The temperature is constant at 25°C.


-Determine $\Delta$ G° (in kJ/mol).

A)-191.4
B)-2281.4
C)-38.9
D)1903.6
E)-1555.4

Question 45

For a certain process at 355 K, $\Delta$ G = -11.8 kJ and $\Delta$ H = -9.2 kJ.Therefore, $\Delta$ S for the process is

A)0 J/K mol
B)7.3 J/K mol
C)-7.3 J/K mol
D)-25.9 J/K mol
E)25.9 J/K mol

Question 46

For a particular chemical reaction $\Delta$ H = 4.3 kJ and $\Delta$ S = -19 J/K.Under what temperature condition is the reaction spontaneous?

A)When T < -226 K.
B)When T < 226 K.
C)The reaction is spontaneous at all temperatures.
D)The reaction is not spontaneous at any temperature.
E)When T > 226 K.

Question 47

The following reaction takes place at 120°C: H₂O(l) $\to$ H₂O(g) $\Delta$ H = 44.0 kJ/mol $\Delta$ S = 0.119 kJ/mol K Which of the following must be true?

A)The reaction is not spontaneous.
B)The reaction is spontaneous.
C)( $\Delta$ G = 0)
D)( $\Delta$ G < 0)
E)Two of these.

Question 48

A mixture of hydrogen and chlorine remains unreacted until it is exposed to ultraviolet light from a burning magnesium strip.Then the following reaction occurs very rapidly: H₂(g)+ Cl₂(g) $\to$ 2HCl(g)
$\Delta$ G = -45.54 kJ
$\Delta$ H = -44.12 kJ
$\Delta$ S = -4.76 J/K
Which of the following is consistent with this information?

A)The reactants are thermodynamically more stable than the products.
B)The reaction has a small equilibrium constant.
C)The ultraviolet light raises the temperature of the system and makes the reaction more favorable.
D)The negative value for $\Delta$ S slows down the reaction.
E)The reaction is spontaneous,but the reactants are kinetically stable.

Question 49

The following questions refer to the following reaction at constant 25°C and 1 atm.
2Fe(s)+ (3/2)O₂(g)+ 3H₂O(l) $\to$ 2Fe(OH)₃(s) $\Delta$ H = -789 kJ/mol


-Determine $\Delta$ S_surr for the reaction (in kJ/mol K)

A)3.14
B)0.937
C)0.378
D)1.31
E)2.65

Question 50

For the reaction A + B $\to$ C + D, $\Delta$ H° = +40 kJ and $\Delta$ S° = +50 J/K.Therefore,the reaction under standard conditions is

A)spontaneous at temperatures less than 10 K
B)spontaneous at temperatures greater than 800 K
C)spontaneous only at temperatures between 10 K and 800 K
D)spontaneous at all temperatures
E)nonspontaneous at all temperatures

Question 51

When ignited,solid ammonium dichromate decomposes in a fiery display.This is the reaction for a "volcano" demonstration.The decomposition produces nitrogen gas,water vapor,and chromium(III)oxide.The temperature is constant at 25°C.


-Determine $\Delta$ S_univ° (in kJ/mol K).

A)7.66
B)6.39
C)84.3
D)5.22
E)6.03

Question 52

Consider the freezing of liquid water at -10°C.For this process what are the signs for $\Delta$ H, $\Delta$ S,and $\Delta$ G?

A)+ - 0
B)+ - -
C)- + 0
D)- + -
E)- - -

Question 53

When ignited,solid ammonium dichromate decomposes in a fiery display.This is the reaction for a "volcano" demonstration.The decomposition produces nitrogen gas,water vapor,and chromium(III)oxide.The temperature is constant at 25°C.


-Determine $\Delta$ S° reaction (in kJ/mol K).

A)0.2777
B)0.8612
C)0.7475
D)0.6338
E)0.1590

Question 54

At constant pressure,the following reaction 2NO₂(g) $\to$ N₂O₄(g)is exothermic.The reaction (as written)is

A)always spontaneous
B)spontaneous at low temperatures,but not high temperatures
C)spontaneous at high temperatures,but not low temperatures
D)never spontaneous
E)cannot tell

Question 55

The third law of thermodynamics states:

A)The entropy of the universe is increasing.
B)The entropy of the universe is constant.
C)The entropy is zero at 0 K for a perfect crystal.
D)The absolute entropy of a substance decreases with increasing temperature.
E)The entropy of the universe equals the sum of the entropy of system and surroundings.

Question 56

For the process of a certain liquid vaporizing at 1 atm, $\Delta$ H°_vap = 54.2 kJ/mol and $\Delta$ S°_vap= 74.1 J/mol K.Assuming these values are independent of T,what is the normal boiling point of this liquid?

A)731 °C
B)1004 °C
C)458 °C
D)0.731 °C
E)none of these

Question 57

In which case must a reaction be spontaneous at all temperatures?

A)( $\Delta$ H) is positive, $\Delta$ S is positive.
B)( $\Delta$ H) = 0, $\Delta$ S is negative.
C)( $\Delta$ S) = 0, $\Delta$ H is positive.
D)( $\Delta$ H) is negative, $\Delta$ S is positive.
E)None of these.

Question 58

For the process S₈ (rhombic) $\to$ S₈ (monoclinic)at 110°C, $\Delta$ H = 3.21 kJ/mol and $\Delta$ S = 8.70 J/K . mol (at 110°C). Which of the following is correct?

A)This reaction is spontaneous at 110°C (S₈ (monoclinic)is stable).
B)This reaction is spontaneous at 110°C (S₈ (rhombic)is stable).
C)This reaction is nonspontaneous at 110°C (S₈ (rhombic)is stable).
D)This reaction is nonspontaneous at 110°C (S₈ (monoclinic)is stable).
E)Need more data.

Question 59

The following questions refer to the following reaction at constant 25°C and 1 atm.
2Fe(s)+ (3/2)O₂(g)+ 3H₂O(l) $\to$ 2Fe(OH)₃(s) $\Delta$ H = -789 kJ/mol


-Determine $\Delta$ S_univ for the reaction (in kJ/mol K)

A)0.23
B)2.3
C)0.36
D)2.8
E)3.6

Question 60

Given that $\Delta$ H_vap is 53.3 kJ/mol,and the boiling point is 83.4°C,1 atm,if one mole of this substance is vaporized at 1 atm,calculate $\Delta$ G.

A)-150 J
B)150 J
C)639 J
D)-639 J
E)0 J

Question 61

The reaction is allowed to proceed until all substances involved have reached their equilibrium concentrations.Under those conditions,what is $\Delta$ G for the reaction?

A)-1.35 $\times$ 10⁵ kJ
B)98.7 kJ
C)-25.2 kJ
D)135 kJ
E)0

Question 62

The standard molar free energies of formation of NO₂(g)and N₂O₄(g)at 25°C are 51.84 and 98.00 kJ/mol,respectively.What is the value of $\Delta$ G for the reaction written as follows at 25°C if the pressures of both gases are 1.33 atm? 2NO₂ N₂O₄

A)-4.97
B)4.97
C)-6.39
D)-5.68
E)-5.74

Question 63

For the dissociation reaction of the acid HF: HF(aq) H⁺(aq)+ F^-(aq)
$\Delta$ S is observed to be negative.The best explanation is:

A)This is the expected result since each HF molecule produces two ions when it dissociates.
B)Hydration of the ions produces the negative value of $\Delta$ S.
C)The reaction is expected to be exothermic and thus $\Delta$ S should be negative.
D)The reaction is expected to be endothermic and thus $\Delta$ S should be negative.
E)None of these can explain the negative value of $\Delta$ S.

Question 64

Which of the following is not a state function?

A)q
B)G
C)H
D)E
E)P

Question 65

Consider the dissociation of hydrogen: H₂(g) 2H(g)
One would expect that this reaction:

A)will be spontaneous at any temperature
B)will be spontaneous at high temperatures
C)will be spontaneous at low temperatures
D)will not be spontaneous at any temperature
E)will never happen

Question 66

Consider the reaction
2N₂O₅(g) 4NO₂(g)+ O₂(g)
at 25°C for which the following data are relevant:


-Calculate $\Delta$ G° for the reaction at 25°C.

A)-1.35 $\times$ 10⁵ kJ
B)98.7 kJ
C)-25.2 kJ
D)135 kJ
E)0

Question 67

In which reaction is $\Delta$ S° expected to be positive?

A)I₂(g) $\to$ I₂(s)
B)H₂O(l) $\to$ H₂O(s)
C)CH₃OH(g)+ O₂(g) $\to$ CO₂(g)+ 2H₂O(l)
D)2O₂(g)+ 2SO(g) $\to$ 2SO₃(g)
E)none of these

Question 68

For the reaction $\Delta$ H° = 126.4 kJ/mol and $\Delta$ S° = -74.9 J/K mol. At 361°C,what is $\Delta$ G ?

A)153.4 kJ/mol
B)47.6 kJ/mol
C)173.9 kJ/mol
D)78.9 kJ/mol
E)155.0 kJ/mol

Question 69

Consider the reaction
2N₂O₅(g) 4NO₂(g)+ O₂(g)
at 25°C for which the following data are relevant:


-Calculate $\Delta$ S° for the reaction.

A)809.08 J/K
B)89.38 J/K
C)453.76 J/K
D)-265.94 J/K
E)1164.40 J/K

Question 70

For which of the following processes would $\Delta$ S° be expected to be most positive?

A)O₂(g)+ 2H₂(g) $\to$ 2H₂O(g)
B)H₂O(l) $\to$ H₂O(s)
C)NH₃(g)+ HCl(g) $\to$ NH₄Cl(g)
D)2NH₄NO₃(s) $\to$ 2N₂(g)+ O₂(g)+ 4H₂O(g)
E)N₂O₄(g) $\to$ 2NO₂(g)

Question 71

Consider the reaction
2N₂O₅(g) 4NO₂(g)+ O₂(g)
at 25°C for which the following data are relevant:


-Calculate $\Delta$ H° for the reaction.

A)110.022 kJ
B)10.572 kJ
C)121.311 kJ
D)21.861 kJ
E)155.178 kJ

Question 72

The standard free energy of formation of KCl(s)is -408.8 kJ/mol. $\Delta$ G° for the reaction 2KCl(s) $\to$ 2K(s)+ Cl₂(g)is:

A)-408.8 kJ
B)817.6 kJ
C)408.8 kJ
D)-817.6 kJ
E)none of these

Question 73

Consider the following hypothetical reaction at 310 K.Standard free energies of formation are given in parentheses. B $\to$ C
$\Delta$ G° = -32.6 kJ/mol(?)
(176.4 kJ/mol)
Calculate the standard free energy of formation of compound B.

A)209.0 kJ/mol
B)-209.0 kJ/mol
C)143.8 kJ/mol
D)-143.8 kJ/mol
E)none of these

Question 74

Given the following data ( $\Delta$ H_f,S°,respectively)for N₂O₄(l)-20.kJ/mol,209.0 J/K mol,and N₂O₄(g)10.kJ/mol,304.2 J/K mol.Above what temperature (in °C)is the vaporization of N₂O₄ liquid spontaneous?

A)Above -178 °C.
B)Above -231 °C.
C)Above 3 °C.
D)Above 30. °C.
E)Above 42 °C.

Question 75

At 699 K, $\Delta$ G° = -23.25 kJ for the reaction H₂(g)+ I₂(g) 2HI(g).Calculate $\Delta$ G for this reaction if the reagents are both supplied at 10.0 atm pressure and the product is at 1.76 atm pressure.

A)-20.2 kJ
B)20.2 kJ
C)3.1 kJ
D)-43.4 kJ
E)43.4 kJ

Question 76

Which of the following statements is (are)always true?
I.In order for a process to be spontaneous,the entropy of the universe must increase.
II.A system cannot have both energy disorder and positional disorder.
III. $\Delta$ Suniv = IV.S° is zero for elements in their standard states.

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

Question 77

When a stable diatomic molecule spontaneously forms from its atoms,what are the signs of $\Delta$ H°, $\Delta$ S°,and $\Delta$ G°?

A)+ + +
B)+ - -
C)- + +
D)- - +
E)- - -

Question 78

Which of the following is true for this reaction?

A)Both $\Delta$ H° and $\Delta$ S° favor the reaction's spontaneity.
B)Both $\Delta$ H° and $\Delta$ S° oppose the reaction's spontaneity.
C)( $\Delta$ H°) favors the reaction,but $\Delta$ S° opposes it.
D)( $\Delta$ H°) opposes the reaction,but $\Delta$ S° favors it.
E)The reaction cannot occur at room temperature.

Question 79

In which process is $\Delta$ S expected to be positive?

A)a reaction that forms a solid precipitant from aqueous solutions
B)an ideal gas being compressed at a constant temperature and against a constant pressure
C)water freezing below its normal freezing point
D)a spontaneous endothermic process at a constant temperature and pressure
E)none of these

Question 80

Of $\Delta$ S, $\Delta$ S_surr, $\Delta$ S_univ,and $\Delta$ G,which are state functions?

A)( $\Delta$ S), $\Delta$ S_surr, $\Delta$ S_univ,and $\Delta$ G are all state functions.
B)Only $\Delta$ S, $\Delta$ S_univ,and $\Delta$ G are state functions.
C)Only $\Delta$ S and $\Delta$ G are state functions.
D)Only $\Delta$ S, $\Delta$ S_surr,and $\Delta$ S_univ are state functions.
E)Only $\Delta$ S_univ and $\Delta$ G are state functions.