Deck 19: Entropy and Free Energy

Question 1

As defined by Ludwig Boltzmann,the third law of thermodynamics states that

A) there is no disorder in a perfect crystal at 0 K.
B) in a spontaneous process,the entropy of the universe increases.
C) the total entropy of the universe is always increasing.
D) the total mass of the universe is constant.
E) mass and energy are conserved in all chemical reactions.

Answer 1

there is no disorder in a perfect crystal at 0 K.

Question 2

A statement of the first law of thermodynamics is that

A) in a spontaneous process,the entropy of the universe increases.
B) there is no disorder in a perfect crystal at 0 K.
C) the total energy of the universe is always decreasing.
D) the total energy of the universe is constant.
E) mass and energy are conserved in all chemical reactions.

Answer 2

the total energy of the universe is constant.

Question 3

Which of the following linear chain alcohols is likely to have the highest standard entropy in the liquid state?

A) CH₃OH
B) CH₃CH₂OH
C) CH₃CH₂CH₂OH
D) CH₃CH₂CH₂CH₂OH
E) CH₃CH₂CH₂CH₂CH₂OH

Answer 3

CH₃CH₂CH₂CH₂CH₂OH

Question 4

In which reaction is $\Delta$ _rS° expected to be negative?

A) 2C₂H₆(g)+ 7O₂(g) $\to$ 4CO₂(g)+ 6H₂O(l)
B) Ga(l) $\to$ Ga(s)
C) H₂O(l)+ 2SO₂(g) $\to$ H₂SO₄(l)
D) CO₂(g) $\to$ CO₂(s)
E) all of above

Question 5

If a chemical reaction occurs in a direction that has a positive change in entropy then

A) the change in enthalpy must be negative.
B) the reaction must be spontaneous.
C) heat goes from the system into the surroundings.
D) the reaction must be exothermic.
E) the disorder of the system increases.

Question 6

Which of the following changes lead to a $\underline{\text{ decrease }}$ in entropy?

A) the sublimation (vaporization)of dry ice (solid carbon dioxide)
B) sugar dissolving in coffee
C) evaporation of water from a lake
D) diffusion of perfume throughout a room
E) halving the volume of a gas

Question 7

Which of the following statements concerning entropy change is/are true?
1)For a reversible process, )
2)For a spontaneous process, )
3)For a reversible process,such as a phase change, $\Delta$ S = q_rev/T .

A) 1 only
B) 2 only
C) 3 only
D) 2 and 3
E) 1,2,and 3

Question 8

Which of the following compounds has the highest standard entropy per mole at 298 K?

A) H₂O(l)
B) CaCO₃(s)
C) CO(g)
D) SiO₂(s)
E) CH₃OH(l)

Question 9

The following processes occur spontaneously at 25 ^$\circ$ C.Which of these processes is/are endothermic?
1)NH₄NO₃ dissolving in water (which is accompanied by a cooling of the water).
2)the expansion of a real gas into a vacuum (which is accompanied by a cooling of the gas).
3)liquid water in an ice cube tray freezing into ice after being placed in a freezer.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2,and 3

Question 10

When a chemical process occurs under standard conditions,which of the following conditions always apply?
1)Gaseous species are at a pressure of 1 bar.
2)Solution concentrations species are 1 molal.
3)The temperature is 298.15 K.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2,and 3

Question 11

Which of the following statements is/are CORRECT?
1)Spontaneous changes only occur in the direction that leads to equilibrium.
2)Exothermic reactions are always spontaneous.
3)In any chemical reaction,energy must be conserved.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 3
E) 1,2,and 3

Question 12

Which of the following statements concerning entropy is $\underline{\text{ not }}$ correct?

A) The entropy of a system increases as the number of available microstates increases.
B) The entropy of a system is proportional to the natural log of the number of microstates.
C) In a spontaneous process, $\Delta$ S(universe)indicates the extent to which energy is dispersed.
D) The dispersal of matter,such as the spontaneous expansion of a gas,cannot be explained by an increase in entropy.
E) Entropy is a measure of the extent of energy dispersal.

Question 13

For a certain reversible process q = 57.40 kJ at 36.6 ^$\circ$ C.What is $\Delta$ S for the process?

A) 0.185 J/K
B) 185 J/K
C) 1.57 J/K
D) (-0.185) J/K
E) 2130 J/K

Question 14

For which of the following reactions will the entropy of the system decrease?

A) 2 NH₃(g) $\to$ N₂(g)+ 3 H₂(g)
B) 2 C(s)+ O₂(g) $\to$ 2 CO(g)
C) CaCO₃(s) $\to$ CaO(s)+ CO₂(g)
D) 2 NO₂(g) $\to$ N₂O₄(g)
E) NaOH(s) $\to$ Na⁺(aq)+ OH^-(aq)

Question 15

The second law of thermodynamics states that

A) in a spontaneous process,the entropy of the universe increases.
B) there is no disorder in a perfect crystal at 0 K.
C) the total energy of the universe is always increasing.
D) the total energy of the universe is constant.
E) mass and energy are conserved in all chemical reactions.

Question 16

Which of the following reactions would be expected to have a positive entropy change, ∆_rS° > 0?
1. 2 SO2(g) + O2(g) → 2 SO3(g)
2. Ba(OH)2(s) → BaO(s) + H2O(g)
3. CO(g)+ 2 H₂(g) $\to$ CH₃OH( )

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1 and 3

Question 17

Arrange the following reactions in order of increasing $\Delta$ _rS° value.
1.H₂(g)+ F₂(g) $\to$ 2HF(g)
2)NH₄NO₃(s) $\to$ N₂O(g)+ 2H₂O(l)
3)(NH₄)₂Cr₂O₇(s) $\to$ Cr₂O₃(s)+ 4H₂O(l)+ N₂(g)

A) 1 < 2 < 3
B) 2 < 3 < 1
C) 3 < 1 < 2
D) 1 < 3 < 2
E) 2 < 1 < 3

Question 18

What is the change in entropy for a system going from 189 possible microstates to 734 possible microstates? (k = 1.381  10^-23 J/K)

A) J/K
B) J/K
C) ( )J/K
D) J/K
E) ( ) J/K

Question 19

Which of the following statements concerning entropy is/are CORRECT?
1)The entropy of a substance increases when converted from a liquid to a solid.
2)The entropy of a substance decreases as its temperature increases.
3)All substances have positive entropy values at temperatures above 0 K.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2,and 3

Question 20

Which of the following statements regarding the spontaneity of chemical and physical changes is correct?

A) A reaction may be spontaneous only in one direction.
B) A process can sometimes be spontaneous in the direction that moves it away from equilibrium.
C) Endothermic processes are never spontaneous.
D) A reactant favored process cannot be spontaneous.
E) Spontaneous changes occur only in the direction that leads to equilibrium.

Question 21

Diluting concentrated sulfuric acid with water can be dangerous.The temperature of the solution can increase rapidly.What are the signs of $\Delta$ _rH, $\Delta$ _rS,and $\Delta$ _rG for this process?

A) ( $\Delta$ _rH) < 0, $\Delta$ _rS > 0, $\Delta$ _rG < 0
B) ( $\Delta$ _rH) < 0, $\Delta$ _rS < 0, $\Delta$ _rG < 0
C) ( $\Delta$ _rH) < 0, $\Delta$ _rS > 0, $\Delta$ _rG > 0
D) ( $\Delta$ _rH) > 0, $\Delta$ _rS > 0, $\Delta$ _rG < 0
E) ( $\Delta$ _rH) > 0, $\Delta$ _rS < 0, $\Delta$ _rG > 0

Question 22

Hydrogen gas is a non-polluting fuel.Hydrogen gas may be prepared by electrolysis of water.2 H₂O( ) $\to$ 2 H₂(g)+ O₂(g)
Predict the signs of $\Delta$ _rH and $\Delta$ _rS for the production of hydrogen gas by electrolysis of water.

A) ( $\Delta$ _rH) > 0 and $\Delta$ _rS > 0
B) ( $\Delta$ _rH) < 0 and $\Delta$ _rS > 0
C) ( $\Delta$ _rH) > 0 and $\Delta$ _rS < 0
D) ( $\Delta$ _rH) < 0 and $\Delta$ _rS < 0
E) ( $\Delta$ _rH) = 0 and $\Delta$ _rS < 0

Question 23

Calculate S⁰ for O₃(g)if the standard entropy change for the reaction below is 548 J/K.mol-rxn and S⁰[O₂(g)] = 205 J/K.mol.
8O₃(g) $\to$ 12O₂(g)

A) 364 J/K.mol-rxn
B) 478 J/K.mol-rxn
C) 239 J/K.mol-rxn
D) (-117) J/K.mol-rxn
E) (-59) J/K.mol-rxn

Question 24

What is the sign of $\Delta$ Hº(system)and $\Delta$ Sº(system)if a chemical reaction is nonspontaneous at all temperatures under standard conditions?

A) ( $\Delta$ Hº)(system)is negative,and $\Delta$ Sº(system)is positive.
B) ( $\Delta$ Hº)(system)is negative,and $\Delta$ Sº(system)is negative.
C) ( $\Delta$ Hº)(system)is positive,and $\Delta$ Sº(system)is positive.
D) ( $\Delta$ Hº)(system)is positive,and $\Delta$ Sº(system)is negative.
E) none of these

Question 25

For the process Br₂(l) $\to$ 2Br(g),

A) ( $\Delta$ H) is + and $\Delta$ S is + for the reaction.
B) ( $\Delta$ H) is + and $\Delta$ S = 0 for the reaction.
C) ( $\Delta$ H) is - and $\Delta$ S is - for the reaction.
D) ( $\Delta$ H) is - and $\Delta$ S is + for the reaction.
E) ( $\Delta$ H) is + and $\Delta$ S is - for the reaction.

Question 26

If a chemical reaction is exothermic,but not spontaneous,which of the following must be true?

A) ( $\Delta$ _rG) > 0, $\Delta$ _rS > 0 and $\Delta$ _rH > 0
B) ( $\Delta$ _rG) < 0, $\Delta$ _rS > 0 and $\Delta$ _rH > 0
C) ( $\Delta$ _rG) > 0, $\Delta$ _rS < 0 and $\Delta$ _rH > 0
D) ( $\Delta$ _rG) < 0, $\Delta$ _rS < 0 and $\Delta$ _rH < 0
E) ( $\Delta$ _rG) > 0, $\Delta$ _rS < 0 and $\Delta$ _rH < 0

Question 27

Calculate the standard entropy change for the following reaction,
2 SO₂(g)+ O₂(g) $\to$ 2 SO₃(g)
Given S ^$\circ$ [SO₂(g)] = 248.2 J/K.mol,S ^$\circ$ [O₂(g)] = 205.1 J/K.mol,and S ^$\circ$ [SO₃(g)] = 256.8 J/K.mol.

A) -196.5 J/K·mol-rxn
B) -94.0 J/K·mol-rxn
C) -187.9 J/K·mol-rxn
D) +187.9 J/K·mol-rxn
E) +196.5 J/K·mol-rxn

Question 28

For the combustion of acetylene at 298.15 K,
2 C₂H₂(g)+ 5 O₂(g) $\to$ 4 CO₂(g)+ 2 H₂O(g)
Calculate $\Delta$ S ^$\circ$ (universe)given $\Delta$ S ^$\circ$ (system)= -194.6 J/K and $\Delta$ H ^$\circ$ (system)= -2511.2 kJ.

A) -2453.2 J/K
B) -186.2 J/K
C) +186.2 J/K
D) +1290.4 J/K
E) +8228.0 J/K

Question 29

When a real gas is compressed from low pressure to a higher pressure,its temperature increases.Predict the signs $\Delta$ H and $\Delta$ S.

A) ( $\Delta$ H) < 0 and $\Delta$ S < 0
B) ( $\Delta$ H) < 0 and $\Delta$ S > 0
C) ( $\Delta$ H) > 0 and $\Delta$ S < 0
D) ( $\Delta$ H) > 0 and $\Delta$ S > 0
E) ( $\Delta$ H) < 0 and $\Delta$ S = 0

Question 30

If $\Delta$ _rG ^$\circ$ > 0 for a reaction at all temperatures,then $\Delta$ _rH ^$\circ$ is ____ and $\Delta$ _rS ^$\circ$ is ____.

A) negative,positive
B) positive,negative
C) negative,negative
D) positive,positive
E) positive,either positive or negative

Question 31

The dissolution of ammonium nitrate occurs spontaneously in water at 25 ^$\circ$ C.As NH₄NO₃ dissolves,the temperature of the water decreases.What are the signs of $\Delta$ _rH, $\Delta$ _rS,and $\Delta$ _rG for this process?

A)( $\Delta$ _rH) > 0, $\Delta$ _rS < 0, $\Delta$ _rG > 0
B) ( $\Delta$ _rH) > 0, $\Delta$ _rS > 0, $\Delta$ _rG > 0
C) ( $\Delta$ _rH) > 0, $\Delta$ _rS > 0, $\Delta$ _rG < 0
D)( $\Delta$ _rH) < 0, $\Delta$ _rS < 0, $\Delta$ _rG < 0
E) ( $\Delta$ _rH) < 0, $\Delta$ _rS > 0, $\Delta$ _rG > 0

Question 32

The standard entropy for the formation of SF₆(g)from the elements,
S(s)+ 3 F₂(g) $\to$ SF₆(g)
Is -348.7 J/K.mol-rxn at 298.15 K.Calculate the standard molar entropy of SF₆(g)given S ^$\circ$ [S(s)] = 32.1 J/K.mol and S ^$\circ$ [F₂(g)] = 202.8 J/K.mol.

A) -988.6 J/K.mol
B) +291.8 J/K.mol
C) -291.8 J/K.mol
D) -113.2 J/K.mol
E) +113.8 J/K.mol

Question 33

If a cube of ice at 0 ^$\circ$ C is placed outside on a warm summer day,the ice will melt spontaneously.What are the signs of $\Delta$ _rH, $\Delta$ _rS,and $\Delta$ _rG for this process?

A) ( $\Delta$ _rH) < 0, $\Delta$ _rS > 0, $\Delta$ _rG < 0
B) ( $\Delta$ _rH) < 0, $\Delta$ _rS < 0, $\Delta$ _rG < 0
C) ( $\Delta$ _rH) < 0, $\Delta$ _rS > 0, $\Delta$ _rG > 0
D) ( $\Delta$ _rH) > 0, $\Delta$ _rS > 0, $\Delta$ _rG < 0
E) ( $\Delta$ _rH) > 0, $\Delta$ _rS < 0, $\Delta$ _rG > 0

Question 34

A change of state that occurs in a system is accompanied by 58.8 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(surroundings)is:

A) -196 J/K
B) -58.8 kJ/K
C) 196 J/K
D) 58.8 kJ/K
E) 241 kJ/K

Question 35

Calculate the standard entropy change for the following reaction.
(J/mol.K)

A) -198.7 J/K.mol-rxn
B) 198.7 J/K.mol-rxn
C) 184.3 J/K.mol-rxn
D) -184.3 J/K.mol-rxn
E) -129.8 J/K.mol-rxn

Question 36

Which of the following is true for the vaporization of a liquid substance?

A) ( $\Delta$ S) = 0 and $\Delta$ H = 0.
B) ( $\Delta$ S) < 0 and $\Delta$ H < 0.
C) ( $\Delta$ S) < 0 and $\Delta$ H > 0.
D) ( $\Delta$ S) > 0 and $\Delta$ H > 0.
E) ( $\Delta$ S) > 0 and $\Delta$ H < 0.

Question 37

Use the following thermodynamic data
Species



To calculate $\Delta$ S ^$\circ$ (universe)for the formation of Fe₂O₃(s)at 298.15 K.
3 Fe(s)+ 2 O₂(g) $\to$ Fe₃O₄(s)

A) -3404 J/K
B) -1162 J/K
C) +561.2 J/K
D) +3404 J/K
E) +7639 J/K

Question 38

A flask containing helium gas is released into a closed room.Which of the following ideas regarding entropy is $\textbf{ false? }$

A) ( $\Delta$ S)(system)> 0
B) Matter is dispersed.
C) ( $\Delta$ S)(universe)> 0
D) This process is spontaneous.
E) All of these statements are true.

Question 39

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)(universe)> 0
C) ( $\Delta$ S)(system)< 0
D) ( $\Delta$ S)(surroundings)> 0
E) none of these

Question 40

For the reaction given below, $\Delta$ H⁰ = -1516 kJ at 25 ^$\circ$ C and $\Delta$ S⁰ = -432.8 J/K at 25 ^$\circ$ C.This reaction is spontaneous ____.
SiH₄(g)+ 2O₂(g) $\to$ SiO₂(s)+ 2H₂O

A) only below a certain temperature
B) only above a certain temperature
C) at all temperatures
D) at no temperatures
E) cannot tell from the information available

Question 41

At what temperatures will a reaction be spontaneous if $\Delta$ _rH ^$\circ$ = +117 kJ and $\Delta$ _rS ^$\circ$ = -35 J/K?

A) All temperatures below 94.1 K
B) Temperatures between 12.7 K and 135 K
C) All temperatures above 94.1 K
D) The reaction will be spontaneous at any temperature.
E) The reaction will never be spontaneous.

Question 42

All of the following relationships are true EXCEPT

A) .
B) .
C) .
D) .
E) .

Question 43

Estimate the boiling point of ethanol given the following thermodynamic parameters.

A) 22 ^$\circ$ C
B) 44 ^$\circ$ C
C) 61 ^$\circ$ C
D) 69 ^$\circ$ C
E) 91 ^$\circ$ C

Question 44

At what temperatures will a reaction be spontaneous if $\Delta$ _rH ^$\circ$ = +62.4 kJ and $\Delta$ _rS ^$\circ$ = +301 J/K?

A) All temperatures below 207 K.
B) All temperatures above 207 K.
C) Temperatures between 179 K and 235 K.
D) The reaction will be spontaneous at any temperature.
E) The reaction will never be spontaneous.

Question 45

Calculate $\Delta$ _rG ^$\circ$ for the reaction below at 25.0 ^$\circ$ C
2 Na(s)+ 2 H₂O( ) $\to$ 2 NaOH(aq)+ H₂(g)
Given $\Delta$ _rH ^$\circ$ = -366.6 kJ/mol-rxn and $\Delta$ _rS ^$\circ$ = -154.2 J/K.mol-rxn.

A) -371.2 kJ/mol-rxn
B) -320.6 kJ/mol-rxn
C) -215.4 kJ/mol-rxn
D) +371.2 kJ/mol-rxn
E) +4634.9 kJ/mol-rxn

Question 46

What is $\Delta$ _rG° at 500.0 K for the following reaction?
Zn(s)+ H₂O(g) $\to$ ZnO(s)+ H₂(g)

A) 80.7 kJ/mol-rxn
B) -80.7 kJ/mol-rxn
C) 92.0 kJ/mol-rxn
D) -92.0 kJ/mol-rxn
E) -136.7 kJ/mol-rxn

Question 47

Given the following,determine $\Delta$ _rG° at 298 K for the precipitation reaction,
Ag⁺(aq)+I^-(aq) $\to$ AgI(s)

A) -91.7 kJ/mol-rxn
B) -40.7 kJ/mol-rxn
C) 91.7 kJ/mol-rxn
D) 40.7 kJ/mol-rxn
E) 62.5 kJ/mol-rxn

Question 48

What is $\Delta$ G° at 298 K for the following reaction?
H₂(g)+ Br₂(g) $\to$ 2HBr(g); $\Delta$ _rH ^$\circ$ = -103.8 kJ/mol-rxn; $\Delta$ _rS ^$\circ$ = 21.3 J/K.mol-rxn at 298 K

A) -97.45 kJ/mol-rxn
B) 110.1 kJ/mol-rxn
C) -110.1 kJ/mol-rxn
D) 6.451 $\times$ 10³ kJ/mol-rxn
E) -6.451 $\times$ 10³ kJ/mol-rxn

Question 49

For which of the following substances is the standard free energy of formation not equal to zero at 298 K?

A) He(g)
B) Er(s)
C) Cl₂(g)
D) Ba(g)
E) Fe(s)

Question 50

For a reaction, $\Delta$ _rH ^$\circ$ = -208.8 kJ and $\Delta$ _rS ^$\circ$ = -308.2 J/K.At what temperature will $\Delta$ _rG ^$\circ$ = 0.00 kJ?

A) 0.68 K
B) 677.5 K
C) 1476 K
D) 6435 K
E) ( $\Delta$ G) is less than 0.00 kJ at any temperature.

Question 51

Thermodynamics can be used to determine all of the following EXCEPT

A) the temperature at which a reaction is spontaneous.
B) the extent to which a reaction occurs.
C) the direction in which a reaction is spontaneous.
D) the rate of reaction.
E) the entropy change of a reaction.

Question 52

Given that
S(g)+ O₂(g) $\to$ SO₂(g) $~~~~~~~~$$~~~~~~~~$$\Delta$ _rG ^$\circ$ = -300.1 kJ/mol-rxn
2 S(g)+ 3 O₂(g) $\to$ 2 SO₃(g) $~~~~~~~~$$\Delta$ _rG ^$\circ$ = -742.1 kJ/mol-rxn
Calculate $\Delta$ _fG ^$\circ$ of the following reaction:
SO₂(g)+ 1/2 O₂(g) $\to$ SO₃(g)

A) -1042.2 kJ/mol-rxn
B) -71.0 kJ/mol-rxn
C) +2.47 kJ/mol-rxn
D) +71.0 kJ/mol-rxn
E) +1042.2 kJ/mol-rxn

Question 53

Given the following and that R = 8.314 J/K.mol,determine K at 298K for the reaction,
AgCl(s) $\to$ Ag⁺(aq)+ Cl^-(aq)

A)
B)
C)
D)
E)

Question 54

A reaction is product-favored when

A) Q < K and _rG < 0.
B) Q < K and _rG > 0.
C) Q = K and _rG = 0.
D) Q > K and _rG < 0.
E) Q > K and _rG > 0.

Question 55

Calculate $\Delta$ _rG ^$\circ$ for the reaction below at 25.0 $\Delta$ C
CH₄(g)+ H₂O(g) $\to$ 3 H₂(g)+ CO(g)
Given $\Delta$ _fG ^$\circ$ [CH₄(g)] = -50.8 kJ/mol, $\Delta$ _fG ^$\circ$ 10 [H₂O(g)] = -228.6 kJ/mol, $\Delta$ _fG ^$\circ$ 10 [H₂(g)] = 0.0 kJ/mol,and $\Delta$ _fG ^$\circ$ [CO(g)] = -137.2 kJ/mol.

A) -416.3 kJ/mol-rxn
B) -142.2 kJ/mol-rxn
C) +142.2 kJ/mol-rxn
D) +315.0 kJ/mol-rxn
E) +416.3 kJ/mol-rxn

Question 56

Given the following,determine $\Delta$ _fG° at 298 K for PbO.
Pb(s)+ PbO₂(s) $\to$ 2PbO(s); $\Delta$ _rG° = -158.5 kJ/mol-rxn at 298K

A) -187.9 kJ/mol
B) -375.8 kJ/mol
C) 58.8 kJ/mol
D) 29.4 kJ/mol
E) 117.6 kJ/mol

Question 57

For a chemical system, $\Delta$ _rG ^$\circ$ and $\Delta$ _rG are equal when

A) the system is in equilibrium.
B) the reactants and products are in standard state conditions.
C) the equilibrium constant,K,equals 0.
D) the reaction quotient,Q,is less than 1.
E) the reactants and products are in the gas phase.

Question 58

$\Delta$ G ^$\circ$ < 0 for a reaction indicates that

A) the reaction favors formation of reactants.
B) the reaction is spontaneous.
C) the reaction is nonspontaneous.
D) the reaction is at equilibrium.
E) the reaction cannot reach equilibrium.

Question 59

Which of the following is correct for the condensation of gaseous ammonia at -38°C? The normal boiling point of ammonia is -33°C.

A) ( $\Delta$ H) < 0, $\Delta$ S > 0,and $\Delta$ G > 0.
B) ( $\Delta$ H) < 0, $\Delta$ S < 0,and $\Delta$ G < 0.
C) ( $\Delta$ H) > 0, $\Delta$ S < 0,and $\Delta$ G < 0.
D) ( $\Delta$ H) = 0, $\Delta$ S = 0,and $\Delta$ G < 0.
E) ( $\Delta$ H) > 0, $\Delta$ S > 0,and $\Delta$ G > 0.

Question 60

For a chemical reaction,if $\Delta$ _rG ^$\circ$ = 0,then ____.

A) K > 1
B) K = 0
C) K < 0
D) K < 1
E) K = 1

Question 61

What is the equilibrium constant for reaction below at 25 ^$\circ$ C? (R = 8.314 J/K.mol)
2 NO(g)+ O₂(g) 2 NO₂(g)
Given $\Delta$ _fG ^$\circ$ [NO(g)] = +86.6 kJ/mol and $\Delta$ _fG ^$\circ$ [NO₂(g)] = +51.2 kJ/mol.

A) 3.9 $\times$ 10^-13
B) 1.0
C) 2.6 $\times$ 10¹²
D) 1.6 $\times$ 10⁶
E) 3.8 $\times$ 10²⁸

Question 62

The total entropy of the universe is always increasing.This is a statement of the ________ law of thermodynamics.

Question 63

Use the standard entropies for liquid water and steam to estimate the enthalpy of vaporization of water at its normal boiling point. $\Delta$ S ^$\circ$ [H₂O( )] = 69.9 J/K.mol and $\Delta$ S ^$\circ$ [H₂O(g)] = 188.8 J/K.mol.

Question 64

________ changes only occur in the direction that leads toward chemical equilibrium.

Question 65

For any process,the change in entropy of the universe equals the sum of the entropy changes for the system and for the ________.

Question 66

At what temperature (in kelvin units)is the entropy of a pure crystal 0.0 J/K.

Question 67

The standard free energy change associated with the dissolution of ammonium nitrate in water is -6.73 kJ/mol at 298.15 K.

NH₄NO₃(s) NH₄NO₃(aq)
What is the equilibrium constant for the reaction? (R = 8.314 J/K.mol)

A) 1.9 $\times$ 10^-3
B) 6.6 $\times$ 10^-2
C) 1.0
D) 15
E) 5.2 $\times$ 10²

Question 68

The standard free energy change for a chemical reaction is +13.3 kJ/mol.What is the equilibrium constant for the reaction at 125 ^$\circ$ C? (R = 8.314 J/K.mol)

A) 2.8 $\times$ 10^-6
B) 2.0 $\times$ 10^-5
C) 4.7 $\times$ 10^-3
D) 1.8 $\times$ 10^-2
E) 2.1 $\times$ 10²

Question 69

The solubility product equilibrium constant,K_sp,of silver bromide is
5.4 $\times$ 10^-13 at 298 K.AgBr(s) Ag⁺(aq)+ Br^-(aq)
What is $\times$ _rG ^$\circ$ ? (R = 8.314 J/K.mol)

A) (-3.0 $\times$ 10¹) kJ/mol
B) (-5.87 )kJ/mol
C) 5.87 kJ/mol
D) 3.0 $\times$ 10¹ kJ/mol
E) 7.0 $\times$ 10¹ kJ/mol

Question 70

Does the formation of complex molecules such as proteins and nucleic acids from more simple molecules contradict the second law of thermodynamics?

Question 71

In any chemical process,energy must be conserved.This is a statement of the ________ law of thermodynamics.

Question 72

What is the equilibrium constant for the reaction below at 25 ^$\circ$ C? (R = 8.314 J/K.mol)

MgCO₃(s) MgO(s)+ CO₂(g)

Given $\Delta$ _fG ^$\circ$ [MgCO₃(s)] = -1028.2 kJ/mol, $\Delta$ _fG [MgO(s)] = -568.8 kJ/mol,and $\Delta$ _fG ^$\circ$ [CO₂(g)] = -394.4 kJ/mol.

A) 4.0 $\times$ 10^-12
B) 0.97
C) 1.0
D) 1.0 $\times$ 10⁴
E) 2.5 $\times$ 10¹¹

Question 73

The change in entropy for any process is not dependent upon the pathway by which the process occurs.In other words,the change in entropy for any process is a(n)________ function.

Question 74

Calculate $\Delta$ _rG ^$\circ$ for the following reaction at 425 ^$\circ$ C,
2 HI(g) H₂(g)+ I₂(g)
Given K = 0.018.(R = 8.314 J/K.mol)

A) 6.12 $\times$ 10³ J
B) 1.05 $\times$ 10⁴ J
C) 1.42 $\times$ 10⁴ J
D) 2.33 $\times$ 10⁴ J
E) 3.34 $\times$ 10⁵ J

Question 75

The standard free energy of formation of KBr(s)is -380.4 kJ/mol. $\Delta$ _rG° for the reaction 2KBr(s) $\to$ 2K(s)+ Br₂(l)is:

A) 760.8 kJ
B) 380.4 kJ
C) -760.8 kJ
D) -380.4 kJ
E) none of these

Question 76

Consider the following reaction:
2C(s)+ 2H₂(g) $\to$ C₂H₄(g); $\Delta$ _rH° = 52.47 kJ; $\Delta$ _rS° = -53.5 J/K at 298 K
What is the equilibrium constant at 298 K for this reaction? (R = 8.314 J/K.mol)

A) 1.0 $\times$ 10^-12
B) 1.0
C) 1.6 $\times$ 10^-3
D) 9.8 $\times$ 10¹¹
E) 6.4 $\times$ 10^-10