Deck 12: Thermodynamics-Why Chemical Reactions Happen

Question 1

Which of the following statements regarding spontaneous processes is NOT true?

A)Spontaneous processes are exothermic.
B)Spontaneous processes proceed without outside intervention once initiated.
C)Spontaneous reactions are not always rapid.
D)The motional freedom of particles tends to increase during spontaneous change.
E)Particles tend to become more spread out during spontaneous change.

Answer 1

Spontaneous processes are exothermic.

Question 2

Boltzmann derived the relationship S = k ln W,where W is the __________

A)number of microstates.
B)vibrational energy.
C)kinetic energy.
D)Wentworth factor.
E)potential energy.

Answer 2

number of microstates.

Question 3

Of the three modes of molecular motion-vibration,rotation,and translation-which requires the greatest amount of energy to cause an excitation from the ground state to the first excited state?

A)vibration
B)rotation
C)translation
D)They all require the same amount of energy.
E)None,as quantized energy states do not apply to these motions.

Answer 3

vibration

Question 4

Which of the following must be true for the microstates of a system?
I.The energy of each microstate equals the energy of the system.
II.The entropy of each microstate equals the entropy of the system.
III.The number of microstates equals the entropy of the system.

A)I only
B)II only
C)III only
D)I and III only
E)I,II,and III are all true

Question 5

An oxygen molecule at room temperature can access the largest number of accessible microstates associated with which mode of molecular motion?

A)vibrational
B)kinetic
C)translational
D)elastic
E)Boltzmann

Question 6

Which of the following processes is NOT spontaneous?

A)Iron in moist air rusts.
B)Carbon dioxide and water react to form sugar and oxygen gas.
C)Liquid water in a freezer turns to ice.
D)A spark ignites a mixture of propane and air.
E)Baking soda (sodium hydrogen carbonate)reacts with lemon juice (dilute citric acid).

Question 7

Which of the following is the best definition of a microstate as it pertains to entropy on the molecular level?

A)the state (solid,liquid,or gas)of a small cluster of atoms or molecules
B)a property of a small cluster of atoms and molecules,such as temperature,that is independent of how the property was achieved
C)the set of vibrational,rotational,and translational energy levels in a system
D)a unique specification of the vibrational,rotational,and translational states of a single molecule in a system
E)a unique specification of the vibrational,rotational,and translational states of all of the particles in a system

Question 8

Which of the following statements regarding entropy is NOT true?

A)It is a measure of the distribution of energy in a system at a specific temperature.
B)It is a measure of the number of accessible microstates in a pure substance.
C)It is an index of the randomness of the particles in a system.
D)It is a property of the universe that increases during a spontaneous process.
E)It is a property of a system that may increase or decrease during a spontaneous process.

Question 9

According to the second law of thermodynamics,the entropy change in an isolated system ( $\Delta$ S_sys)during a spontaneous process must be __________

A)greater than zero.
B)less than zero.
C)equal to zero.
D)greater than or equal to zero.
E)greater than,less than,or equal to zero.

Question 10

The following figures represent distributions of two types of gas molecules between two containers connected by an open tube.In which figure is the entropy of the system maximized?

A)
B)
C)
D)
E)These are equal entropy systems.

Question 11

When the volume of a gas is increased,the energy separation between microstates __________

A)increases.
B)decreases.
C)remains unchanged.
D)becomes infinite.
E)disappears.

Question 12

The following figures represent distributions of gas molecules between two containers connected by an open tube.In which figure is the entropy of the system maximized?

A)
B)
C)
D)
E)These are equal entropy systems.

Question 13

Which of the following is a driving force behind spontaneous reactions?

A)A solid is formed.
B)Heat is absorbed.
C)The reaction is rapid.
D)The motional freedom of particles increases.
E)The enthalpy of the particles increases.

Question 14

Which of the following states of motion has the highest number of occupied excited states at room temperature-rotational,vibrational,or translational?

A)rotational
B)vibrational
C)translational
D)The number of occupied excited states is the same for the three modes of motion.
E)None of these,as excited states do not apply to these motions.

Question 15

What modes of motion does a molecule of chlorine have?

A)translational,rotational,and vibrational
B)kinetic energy and potential energy
C)microstate and macrostate
D)Boltzmann and non-Boltzmann
E)all of the above

Question 16

The following figures represent distributions of gas molecules between two containers connected by an open tube.Which one represents the configuration with the largest number of equivalent microstates (most ways of achieving it)?

A)
B)
C)
D)
E)

Question 17

The following figures represent distributions of two types of gas molecules between two containers connected by an open tube.Which one represents the configuration with the largest number of equivalent microstates (most ways of achieving it)?

A)
B)
C)
D)
E)

Question 18

Given one mole of each of the following,which of the following has the highest number of accessible microstates?

A)Ice,H₂O(s),at 273 K
B)Liquid water,H₂O( ),at 373 K
C)Steam,H₂O(g),at 373 K
D)Propane,CH₃CH₂CH₃(g),at 373 K
E)Butane,CH₃CH₂CH₂CH₃(g),at 373 K

Question 19

The entropy change in a system ( $\Delta$ S_sys)during a spontaneous process must be __________

A)greater than zero.
B)less than zero.
C)equal to zero.
D)greater than or equal to zero.
E)greater than,less than,or equal to zero.

Question 20

Which of the following statements is a valid definition of entropy?

A)It is a measure of the average kinetic energies of the particles in a system.
B)It is a measure of the enthalpy changes during a spontaneous change.
C)It is a measure of how the temperature changes during a spontaneous change.
D)It is a measure of how randomly arranged the particles in a system are.
E)It is a measure of how dispersed the energy of a system is.

Question 21

At 0 K,the entropy of a perfect crystal is __________

A)> 0
B)= 0
C)< 0
D)> 0,= 0,or < 0,depending on the chemical structure of the crystal.
E)> 0 or = 0,depending on the chemical structure of the crystal.

Question 22

Which of the following probably has the highest entropy at 298 K?

A)

B)

C)

D)

E)

Question 23

Which of the following are listed in order of increasing standard molar entropy?

A)Au(s)< Au(g)< H₂O( )< CH₃OH( )< H₂O(g)
B)Au(s)< H₂O( )< CH₃OH( )< Au(g)< H₂O(g)
C)Au(s)< H₂O( )< CH₃OH( )< H₂O(g)< Au(g)
D)H₂O( )< CH₃OH( )< Au(s)< Au(g)< H₂O(g)
E)H₂O( )< Au(s)< CH₃OH( )< H₂O(g)< Au(g)

Question 24

Indicate which of the following has the highest entropy at 298 K.

A)0.5 g of HCN
B)1 mol of HCN
C)2 kg of HCN
D)2 mol of HCN
E)All of the above have the same entropy at 298 K.

Question 25

Which of the following statements regarding absolute and standard entropies is NOT true?

A)The standard entropy of a solution is the value of S when the solution is at 298 K and 1 M concentration.
B)The standard entropy of a gas is the value of S when the gas is at 298 K and 1 bar pressure.
C)The standard entropy of a pure solid or liquid is the value of S for its most stable allotrope at 298 K and 1 bar.
D)Elements in their standard states at 298 K and 1 bar have nonzero entropy values.
E)The entropy of a compound increases linearly with temperature.

Question 26

Which of the following is in the correct order of standard state entropy?
I.Diamond < graphite
II.Liquid water < solid water
III.NH₃ < H₂

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

Question 27

The molar entropies of carbon monoxide and carbon dioxide at 25 ^$\circ$ C are 197.7 and 213.8 J/mol . K,respectively.Which has more accessible microstates at 25 ^$\circ$ C? Approximately how many times more?

A)CO,roughly 16 times more
B)CO₂,roughly 1.1 times more
C)CO₂,roughly 1.3 $\times$ 10¹¹ times more
D)CO₂,roughly 6.9 times more
E)CO₂,roughly 1.9 times more

Question 28

Indicate which of the following has the lowest standard molar entropy (S ^$\circ$ ).

A)CH₄(g)
B)CH₃CH₂OH( )
C)H₂O(s)
D)Na(s)
E)He(g)

Question 29

The standard molar entropy of lead(II)bromide (PbBr₂)is 161 J/mol . K.What is the entropy of 2.45 g of PbBr₂?

A)+1.07 J/K
B)-1.07 J/K
C)+161 J/K
D)-161 J/K
E)0 J/K

Question 30

Which of the following is in the correct order of standard state entropy?
I.CO₂(g)< CO(g)
II.Br₂( )< Br₂(g)
III.S₈(s)< S₂(g)

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

Question 31

When carbon monoxide forms a crystal,each molecule can be pictured as having two possible orientations,CO or OC,because the molecular dipole moment is quite small.Assuming two possible microstates for each CO molecule,calculate the value of S when one mole of CO forms a crystalline solid at 0 K.

A)0 J/mol . K
B)2.00 J/mol . Kl
C)5.76 J/mol . K
D)9.57 $\times$ 10^-23 J/mol . K
E)The value of S is too small to calculate.

Question 32

Perfect crystals of carbon monoxide (CO)are difficult to prepare because the very small dipole moment allows a few molecules to align in a pattern like CO OC CO instead of CO CO CO.If such crystals were cooled to 0 K,what would be the value of their absolute entropy?

A)> 0
B)= 0
C)< 0
D)> 0,= 0,or < 0,depending on how carefully it was cooled
E)> 0 or = 0,depending on how carefully it was cooled

Question 33

At 25 ^$\circ$ C,a benzene molecule (C₆H₆)has approximately 1.143 $\times$ 10¹⁴ accessible microstates.Estimate the molar entropy of C₆H₆ at 25.0 ^$\circ$ C to two significant figures.

A)4.5 $\times$ 10^-22 J/ mol . K
B)3.9 J/ mol . K
C)14 J/ mol . K
D)32 J/ mol . K
E)270 J/ mol . K

Question 34

Consider a closed container containing a 1.00 M solution of aqueous HCl at 298 K.Above the solution,air containing both water vapor and HCl gas at their equilibrium vapor pressures exerts a total pressure of 1.00 bar.Which of the following is/are in their thermodynamic standard state?
I.The liquid water
II.The HCl solution
III.The water vapor

A)I only
B)II only
C)III only
D)I and II only
E)I,II,and III are all in their standard state.

Question 35

How many microstates are accessible to one mole of atoms in a perfect crystalline lattice at absolute zero?

A)0
B)1
C)1.381 $\times$ 10^-23
D)52.64
E)6.022 $\times$ 10²³

Question 36

The molar entropy of ammonia,NH₃(g),at 25 ^$\circ$ C is 192.5 J/mol . K.Estimate the number of microstates accessible to a NH₃ molecule at 25 ^$\circ$ C to two significant figures.

A)1.1 $\times$ 10¹⁰
B)1.4 $\times$ 10²⁵
C)6.8 $\times$ 10³³
D)4.0 $\times$ 10⁸³
E)23

Question 37

Which of the following will have the greatest standard molar entropy (S ^$\circ$ )?

A)NH₃(g)
B)He(g)
C)C(s,graphite)
D)H₂O( )
E)CaCO₃(s)

Question 38

Which of the following graphs best depicts the entropy of a pure substance as the temperature is raised from its solid form through its liquid and gaseous forms? Assume the substance obeys the third law of thermodynamics.

A)

B)

C)

D)

E)

Question 39

The absolute entropy of a NaCl crystal is __________

A)an intensive property and a state function.
B)an intensive property and a path function.
C)an extensive property and a state function.
D)an extensive property and a path function.
E)not appropriately described in terms of an intensive property,an extensive property,a state function,or a path function.

Question 40

Which of the following processes is predicted to decrease the entropy of a system?

A)The number of particles increases.
B)Temperature increases.
C)Volume increases.
D)Pressure increases.
E)All of these increase the entropy of the system.

Question 41

Which of the following processes are reversible in the thermodynamic sense?
I.Iron in the open air rusts.
II.NaCl is dissolved in water and then recovered by the evaporation of the water.
III.The ice in a mixture of ice and water at 0 ^$\circ$ C and 1 atm melts.

A)I only
B)II only
C)III only
D)II and III only
E)I,II,and III are all reversible.

Question 42

During a spontaneous chemical reaction,it is found that $\Delta$ S_sys is less than 0.This means __________

A)" $\Delta$ S_surr is less than 0 and its magnitude is less than $\Delta$ S_sys."
B)" $\Delta$ S_surr is less than 0 and its magnitude is greater than $\Delta$ S_sys."
C)" $\Delta$ S_surr is greater than 0 and its magnitude is less than $\Delta$ S_sys."
D)" $\Delta$ S_surr is greater than 0 and its magnitude is greater than $\Delta$ S_sys."
E)"an error has been made,as S_sys is greater than 0 by necessity for a spontaneous process."

Question 43

If a reaction is spontaneous under a given set of conditions,__________

A)" $\Delta$ S_surr is greater than 0 for the reverse reaction."
B)"the reverse reaction is nonspontaneous."
C)" $\Delta$ S_sys for the reverse reaction is smaller than $\Delta$ S_sys for the forward reaction."
D)"the reverse reaction is also spontaneous."
E)"S_univ is greater than 0 for the reverse reaction."

Question 44

The enthalpy of vaporization of ammonia at its normal boiling point,-33.34 ^$\circ$ C,is approximately 23.35 kJ/mol.What is the entropy change in the surroundings when one mole of liquid ammonia vaporizes at -33.34 ^$\circ$ C in a large room maintained at a temperature of 25.0 ^$\circ$ C?

A)-2.40 $\times$ 10² J/K
B)-78.3 J/K
C)-19.1 J/K
D)+78.3 J/K
E)+2.40 $\times$ 10² J/K

Question 45

Which of the following statements regarding reversible processes is NOT true?

A)Heat transfer between the system and surroundings usually occurs reversibly during ordinary chemical reactions.
B)The change in entropy of the universe is zero during a reversible process.
C)The entropy change in the surroundings is equal and opposite to that of the system during a reversible process.
D)Reversible change would require an infinite amount of time to complete.
E)Heat transfer between the system and surroundings during phase changes can be approximated as reversible.

Question 46

Heat transfer from the system to the surroundings has a large effect on $\Delta$ S_surr __________

A)when the temperature of the surroundings is low.
B)when the temperature of the surroundings is high.
C)when the temperature of the system is low.
D)when the temperature of the system is high.
E)at any temperature,as the amount of heat transferred is independent of temperature.

Question 47

During which of the following processes does the entropy of the system decrease?

A)Salt crystals dissolve in water.
B)Air escapes from a hole in a balloon.
C)Iron and oxygen gas react to form rust.
D)Ice melts in your hand.
E)None of these decrease the entropy of the system.

Question 48

The entropy change of the surroundings, $\Delta$ S_surr,is related to heat transfer q with respect to the system and temperature T by __________

A)-q/T_sys = $\Delta$ S_surr.
B)+q/T_sys = $\Delta$ S_surr.
C)-q/T_surr = $\Delta$ S_surr.
D)q/T_surr = $\Delta$ S_surr.
E)None of these,unless the system undergoes a reversible process.

Question 49

In a spontaneous process,which of the following always increases?

A)the entropy of the system
B)the entropy of the surroundings
C)the entropy of the universe
D)the entropy of the system and the universe
E)the entropy of the system,surroundings,and universe

Question 50

According to the second law of thermodynamics,the change in the entropy of the universe ( $\Delta$ S_univ)during a spontaneous reaction is __________

A)zero.
B)negative.
C)positive.
D)less than the change in entropy of the system ( $\Delta$ S_sys).
E)greater than the change in entropy of the system ( $\Delta$ S_sys).

Question 51

When solid pellets of sodium hydroxide (NaOH)dissolve in water,the temperature of the water can rise dramatically.Taking NaOH as the system,what can you deduce about the signs of the entropy change of the system ( $\Delta$ S_sys)and surroundings ( $\Delta$ S_surr)from this?

A)" $\Delta$ S_sys is less than 0 and $\Delta$ S_surr is less than 0."
B)" $\Delta$ S_sys is less than 0 and $\Delta$ S_surr is greater than 0."
C)" $\Delta$ S_sys is greater than 0 and $\Delta$ S_surr is less than 0."
D)" $\Delta$ S_sys is greater than 0 and $\Delta$ S_surr is greater than 0."
E)"Nothing can be deduced from this limited information."

Question 52

The enthalpy and entropy of fusion of ice at 0.00 ^$\circ$ C are 6.01 kJ/mol and 22.0 J/mol . K,respectively.What is the entropy change of the universe when one mole of ice melts in a large room maintained at 34.00 ^$\circ$ C? Assume the final temperature of the water is 0.00 ^$\circ$ C.

A)+19.6 J/K
B)-19.6 J/K
C)+2.4 J/K
D)-2.4 J/K
E)+41.5 J/K

Question 53

$\Delta$ S_sys can be directly related to the heat q.Which of the following is NOT true regarding this relationship? (If all are true,select E.)

A)" $\Delta$ S_sys can always be determined from the heat transferred during the actual process."
B)"For a reversible spontaneous endothermic process,both q and $\Delta$ S_sys will be positive."
C)"The more heat that is transferred,the larger the magnitude of the entropy change."
D)"The higher the temperature at which heat is transferred,the lower the entropy change."
E)"All of the above are true."

Question 54

The enthalpy of vaporization of water at 100.0 ^$\circ$ C is 40.68 kJ/mol.What is the entropy change in the surroundings when one mole of water vapor condenses at 100.0 ^$\circ$ C in a large room maintained at a temperature of 25.00 ^$\circ$ C?

A)-136.4 J/K
B)-109.0 J/K
C)-40.68 J/K
D)+109.0 J/K
E)+136.4 J/K

Question 55

Which of the following must be true for a spontaneous exothermic process?

A)only $\Delta$ S_sys is less than 0
B)only $\Delta$ S_sys is greater than 0
C)both $\Delta$ S_sys is less than 0 and the magnitude of $\Delta$ S_sys is less than the magnitude of $\Delta$ S_surr
D)both $\Delta$ S_sys is less than 0 and the magnitude of $\Delta$ S_sys is greater than the magnitude of $\Delta$ S_surr
E)either $\Delta$ S_sys is greater than 0 or $\Delta$ S_sys is less than 0 and the magnitude of $\Delta$ S_sys is less than the magnitude of $\Delta$ S_surr

Question 56

The gas above the liquid in a sealed bottle of soda is primarily carbon dioxide.Carbon dioxide is also dissolved in the soda.When the distribution of carbon dioxide between the gas and liquid is at equilibrium,molecules of carbon dioxide in the gas phase can still dissolve in the liquid phase if they strike the surface and are captured.Similarly,molecules of carbon dioxide can escape from the liquid phase.What is the entropy change of the universe, $\Delta$ S_univ,for the dissolution of carbon dioxide under these conditions?

A)" $\Delta$ S_univ is less than 0 because the dissolved carbon dioxide has fewer accessible states."
B)" $\Delta$ S_univ is greater than 0 because the dissolved carbon dioxide has fewer accessible states."
C)" $\Delta$ S_univ equals 0 because this is an equilibrium situation."
D)" $\Delta$ S_univ is less than 0 because the gas dissolves spontaneously."
E)" $\Delta$ S_univ is greater than 0 because the gas dissolves spontaneously."

Question 57

When solid ammonium nitrate (NH₄NO₃)dissolves in water,the temperature of the water can drop dramatically.Taking NH₄NO₃ as the system,predict the signs of the entropy change of the system ( $\Delta$ S_sys)and surroundings ( $\Delta$ S_surr).

A)" $\Delta$ S_sys is less than 0 and $\Delta$ S_surr is less than 0."
B)" $\Delta$ S_sys is less than 0 and $\Delta$ S_surr is greater than 0."
C)" $\Delta$ S_sys is greater than 0 and $\Delta$ S_surr is less than 0."
D)" $\Delta$ S_sys is greater than 0 and $\Delta$ S_surr is greater than 0."
E)" $\Delta$ S_sys equals 0 and $\Delta$ S_surr is less than 0."

Question 58

What is the entropy change in the surroundings when one mole of ice melts at 0.00 ^$\circ$ C in a large room maintained at 32.0 ^$\circ$ C? The heat of fusion of ice is 6.01 kJ/mol.

A)-188 J/K
B)-22.0 J/K
C)-19.7 J/K
D)+19.7 J/K
E)+188 J/K

Question 59

In a spontaneous process,the entropy of the universe __________

A)always increases.
B)always decreases.
C)does not change.
D)may decrease if the entropy of the system decreases sufficiently.
E)may decrease if the entropy of the system increases sufficiently.

Question 60

During which of the following processes does the entropy of the system increase?

A)Water vapor condenses on a cool surface.
B)Helium gas escapes from a hole in a balloon.
C)Calcium carbonate stalactites form in a cave.
D)Water freezes in a freezer.
E)All of these increase entropy of the system.

Question 61

If 3.50 g of Ni are reacted with excess oxygen to form nickel oxide (NiO)under standard state conditions,what is the entropy change for the reaction? 2 Ni(s)+ O₂(g) $\leftrightarrows$ 2 NiO(s)

A)-49.3 J/ K
B)-24.7 J/ K
C)-14.7 J/ K
D)+49.3 J/ K
E)-10.4 J/ K

Question 62

Indicate which one of the following reactions result in a positive $\Delta$ S_sys.

A)AgNO₃(aq)+ NaCl(aq) $\leftrightarrows$ AgCl(s)+ NaNO₃(aq)
B)HCl(g)+ H₂O( ) $\leftrightarrows$ HCl(aq)
C)H₂(g)+ I₂(g) $\leftrightarrows$ 2HI(g)
D)C₂H₂O₂(g) $\leftrightarrows$ 2 CO(g)+ H₂(g)
E)H₂O(g) $\leftrightarrows$ H₂O( )

Question 63

NO gas is converted to NO₂ gas according to the following reaction: NO(g)+ O₂(g) $\to$ NO₂(g).What is the standard entropy change when 0.500 mol of NO gas reacts with 0.500 mol of O₂ gas?

A)+36.6 J/K
B)-176 J/K
C)-83.4 J/K
D)+83.4 J/K
E)-36.6 J/K

Question 64

Which of the following statements regarding free energy is NOT true?

A)Free energy represents the maximum work that a thermodynamic system can perform during a spontaneous change.
B)Free energy represents the minimum work that would be required to make a thermodynamic system undergo a nonspontaneous change.
C)The free energy of a system increases during the course of a spontaneous reaction as the entropy of the universe increases.
D)The Gibbs free energy change of a reaction reflects the work associated with processes happening at constant temperature and pressure.
E)The Gibbs free energy of a spontaneous process is negative.

Question 65

Indicate which one of the following reactions results in a negative $\Delta$ S_sys.

A)H₂O(g) $\leftrightarrows$ H₂O(s)
B)CaCO₃(s) $\leftrightarrows$ CaO(s)+ CO₂(g)
C)CuSO₄ $\leftrightarrows$ 5 H₂O(s) $\leftrightarrows$ CuSO₄(s)+ 5 H₂O(g)
D)14 O₂(g)+ 3 NH₄NO₃(s)+ C₁₀H₂₂ $\leftrightarrows$ 3 N₂(g)+ 17 H₂O(g)+ 10 CO₂(g)
E)CO₂(aq) $\leftrightarrows$ CO₂(g)

Question 66

Determine the standard entropy change of the universe for the reaction, NH₄⁺(aq)+ NO₃^-(aq) $\to$ NH₄NO₃(s),given the following information.Is the reaction spontaneous under standard conditions?

A)"-14.4 J/K,no"
B)"+28.1 J/K,yes"
C)"-94.3 J/K,no"
D)"+108.7 J/K,yes"
E)"+14.5 J/K,yes"

Question 67

In an experiment,1.000 atm of H₂(g)in a 10.00 L container at 25.00 ^$\circ$ C was reacted under standard state conditions with a stoichiometric quantity of O₂(g)to form water vapor.Determine the entropy change.

A)-146.5 J/K
B)-44.3 J/K
C)-18.1 J/K
D)+18.1 J/K
E)+44.3 J/K

Question 68

Determine the change in the standard entropy of the universe for the reaction,H₂(g)+ O₂(g) $\to$ H₂O(g),given the following information:

A)-766.6 J/K
B)+197.4 J/K
C)-197.4 J/K
D)+766.6 J/K
E)-228.6 J/K

Question 69

What is the standard entropy change when 10.0 g of methane reacts with 10.0 g of oxygen to form carbon dioxide and liquid water?

A)-121 J/K
B)-37.9 J/K
C)-243 J/K
D)-154 J/K
E)-16.8 J/K

Question 70

Determine $\Delta$ S ^$\circ$ for the reaction,N₂O₄(g) $\leftrightarrows$ 2 NO₂(g),given the following information.

A)+176.6 J/mol . K
B)-63.8 J/mol . K
C)+63.8 J/mol . K
D)-50.7 J/mol . K
E)-176.7 J/mol . K

Question 71

Determine the entropy change for the reaction,SO₂(g)+ O₂(g) $\to$ SO₃(g),given the following:

A)-196.4 J/K
B)+196.4 J/K
C)-93.9 J/K
D)+93.9 J/K
E)+401.4 J/K

Question 72

Which of the relationships between the free energy change of a system and associated entropy changes is true?

A)" $\Delta$ G_sys = +T $\Delta$ S_sys"
B)" $\Delta$ G_sys = -T $\Delta$ S_sys"
C)" $\Delta$ G_sys = +T $\Delta$ S_univ"
D)" $\Delta$ G_sys = -T $\Delta$ S_surr"
E)" $\Delta$ G_sys = -T $\Delta$ S_univ'

Question 73

What is the entropy change if 4.50 g of CaCO₃(s)is placed in a container and allowed to decompose to CaO(s)and CO₂(g)according to the following reaction? CaCO₃(s) $\leftrightarrows$ CaO(s)+ CO₂(g)

A)+7.22 J/K
B)-161 J/K
C)+35.7 J/K
D)+161 J/K
E)+3.57 J/K

Question 74

Determine $\Delta$ S ^$\circ$ for the reaction,Zn(s)+ 2 HCl(aq) $\leftrightarrows$ ZnCl₂(aq)+ H₂(g),given

A)0 J/K
B)-39.6 J/K
C)+39.6 J/K
D)-38.2 J/K
E)+38.2 J/K

Question 75

Estimate the standard molar entropy of 1.00 M aqueous Mg²⁺ using the following information: $\Delta$ S ^$\circ$ for the reaction,Mg(s)+ 2 HCl(aq) $\leftrightarrows$ MgCl₂(aq)+ H₂(g),is -43.02 J/K.

A)"-52.1 J/K"
B)"+140.J/K"
C)"+138 J/K"
D)"-138 J/K"
E)"-140.J/K"

Question 76

Determine $\Delta$ S ^$\circ$ for the reaction,H₂(g)+ I₂(g) $\leftrightarrows$ 2 HI(g),given the following information.

A)-41.1 J/mol . K
B)-165.3 J/mol . K
C)+398.8 J/mol . K
D)+165.3 J/mol . K
E)+41.1 J/mol . K

Question 77

The enthalpy and entropy of vaporization of acetone at its normal boiling point,-56.4 ^$\circ$ C,are 31.3 kJ/mol and 95.0 J/mol . K,respectively.What would the entropy change of the universe be if one mole of acetone vapor were to condense in a large room maintained at 25.0 ^$\circ$ C?

A)-2.0 $\times$ 10² J/K
B)+10.0 J/K
C)+1.05 $\times$ 10² J/K
D)-10.0 J/K
E)+2.0 $\times$ 10² J/K

Question 78

The enthalpy and entropy of vaporization of ammonia at its normal boiling point,-33.34 ^$\circ$ C,are 23.35 kJ/mol and 97.4 J/mol . K,respectively.What is the entropy change of the universe when one mole of liquid ammonia vaporizes in a large room maintained at 34.0 ^$\circ$ C? Assume the final temperature of the ammonia gas is -33.34 ^$\circ$ C.

A)+21.4 J/K
B)-76.0 J/K
C)+74.1 J/K
D)-21.4 J/K
E)+76.0 J/K

Question 79

In an experiment,1.000 mol of sodium metal is placed in a container and reacted with 4.000 mol of chlorine gas to form sodium chloride under standard state conditions.Determine $\Delta$ S_rxn given the following.

A)-181.2 J/K
B)-90.60 J/ K
C)-724.8 J/K
D)-45.30 J/K
E)-202.1 J/K

Question 80

The enthalpy and entropy of vaporization of ammonia at its normal boiling point,-33.34 ^$\circ$ C,are approximately 23.35 kJ/mol and 97.4 J/mol . K,respectively.What would the entropy change of the universe be if one mole of ammonia vapor were to condense in a large room maintained at 30.0 ^$\circ$ C?

A)"+20.4 J/K"
B)"+77.0 J/K"
C)"-174.4 J/K"
D)"-20.4 J/K"
E)"+174.4 J/K"