Question 1

Which statement best describes the change in entropy during the synthesis of a polymer?

Accepted Answer

A)   The entropy increases.
B)   The entropy remains the same.
C)   The entropy decreases.
D)   There is too little information to assess the change. C

Question 2

Just because a process is spontaneous does not mean that it happens quickly

Accepted Answer

A) True 
 B)False  True

Question 3

Calculate Δ G for the reaction:
SO3( g ) + CaO( s ) → CaSO4( s ) 
Δ G in kJ/mol for: CaO( s ) = − 604.2, SO3( g ) = − 371.1, CaSO4( s ) = − 1320

Accepted Answer

A)   − 2230
B)   − 345
C)   − 323
D)   +189 B

Question 4

Exothermic reactions with negative values of S ° are spontaneous at all temperatures.

Accepted Answer

A) True 
 B)False

Question 5

The use of recycled PET is more cost effective for soda pop bottling than using virgin PET.

Accepted Answer

A) True 
 B)False

Question 6

Calculate Δ G for the reaction:
2 NO2( g ) → 2 N2( g ) + O2( g )  
Δ G in kJ/mol for: NO2( g ) = 51.30

Accepted Answer

A)   +51.3
B)   − 51.3
C)   +103
D)   − 103

Question 7

If a 5.0 L flask holds 0.125 moles of nitrogen at STP, what happens to the entropy of the system upon cooling the gas to -75 C?

Accepted Answer

A)   The entropy increases.
B)   The entropy remains the same.
C)   The entropy decreases.
D)   There is too little information to assess the change.

Question 8

When magnesium sulfite decomposes, the solid transforms into magnesium oxide and sulfur dioxide.
MgSO3( s ) → MgO( s ) + SO2( g )  
At what temperature will this reaction be spontaneous according to Gibb's Energy?
Δ G in kJ/mol for: MgSO3( s ) = − 1172, MgO( s ) = − 569.6, SO2( g ) = − 300.2
Δ H in kJ/mol for: MgSO3( s ) = − 1068, MgO( s ) = − 601.8, SO2( g ) = − 296.8
Δ S in J/mol K for: MgSO3( s ) = 121, MgO( s ) = 27, SO2( g ) = 248.1

Accepted Answer

A)   temps below − 63.1 K
B)   temps below 179.5 K
C)   temps below 415.8 K
D)   temps above 1100 K

Question 9

Calculate Δ S for the reaction:
SO3( g ) + CaO( s ) → CaSO4( s ) 
Δ S in J/mol K for: CaO( s ) = 40, SO3( g ) = 256.6, CaSO4( s ) = 107

Accepted Answer

A)   +404 J/K
B)   − 190 J/K
C)   − 323 J/K
D)   +189 J/K

Question 10

The randomness of a system may be described as its:

Accepted Answer

A)   enthalpy
B)   entropy
C)   kinetic energy
D)   Gibb's energy

Question 11

Two 6.5 L flasks are joined by a 150 mL tube with a stop cock. If 0.25 moles of nitrogen are held in the left flask and the right flask is empty, what happens to the entropy of the system upon opening the valve between the flasks?

Accepted Answer

A)   The entropy increases.
B)   The entropy remains the same.
C)   The entropy decreases.
D)   There is too little information to assess the change.

Question 12

All exothermic processes are spontaneous

Accepted Answer

A) True 
 B)False

Question 13

Consider the combustion of ethane (C2H6): ​
C2H6( g ) + O2( g ) → CO2( g ) + H2O( l )
​
If Δ G ° (in kJ/mol) for: C2H6( g ) = − 32.9, O2( g ) = 0, CO2( g ) = − 394.4, and H2O( l ) = − 237.2; calculate Δ G ° for the reaction.

Accepted Answer

A)   − 2146.2 kJ
B)   − 2935.0 kJ
C)   +2146.2 kJ
D)   − 598.7 kJ

Question 14

According to the Second Law of Thermodynamics, the entropy of the universe must ____ for a spontaneous process?

Accepted Answer

A)   increase
B)   remain the same
C)   decrease

Question 15

Without detailed calculations, predict the sign of Δ S for the system for:
Mg( s ) + O2( g ) → MgO( s )

Accepted Answer

A)   positive (+) 
B)   negative ( − ) 
C)   zero
D)   too little information to assess the change

Question 16

Calculate Δ S for the reaction:
2 SO3( g ) → 2 SO2( g ) + O2( g ) 
Δ S in J/mol K for: SO2( g ) = 248.1, SO3( g ) = 256.6, O2( g ) = 205.0

Accepted Answer

A)   − 537 J/mol K
B)   +188 J/mol K
C)   − 188 J/mol K
D)   +537 J/mol K

Question 17

The degradation of phosgene (COCl2) into CO and Cl2 happens to be non-spontaneous at room temperature and standard state conditions (273 K, 1 atm). What change in temperature must occur to make this a spontaneous reaction?

Accepted Answer

A)   increase T
B)   decrease T
C)   add CO to the COCl2
D)   there is insufficient data to answer

Question 18

The entropy of a system decreases as it moves toward increasing random distributions of particles.

Accepted Answer

A) True 
 B)False

Question 19

Entropy is a state function.

Accepted Answer

A) True 
 B)False

Question 20

At what temperature is the entropy of a water sample the highest?

Accepted Answer

A)   − 15 ° C
B)   2 ° C
C)   99 ° C
D)   135 ° C

Exam 10: Entropy and the Second Law of Thermodynamics

Which statement best describes the change in entropy during the synthesis of a polymer?

Just because a process is spontaneous does not mean that it happens quickly

Calculate Δ G for the reaction: SO₃( g ) + CaO( s ) → CaSO₄( s ) Δ G in kJ/mol for: CaO( s ) = − 604.2, SO₃( g ) = − 371.1, CaSO₄( s ) = − 1320

Exothermic reactions with negative values of S ° are spontaneous at all temperatures.

The use of recycled PET is more cost effective for soda pop bottling than using virgin PET.

Calculate Δ G for the reaction: 2 NO₂( g ) → 2 N₂( g ) + O₂( g ) Δ G in kJ/mol for: NO₂( g ) = 51.30

If a 5.0 L flask holds 0.125 moles of nitrogen at STP, what happens to the entropy of the system upon cooling the gas to -75 C?

Calculate Δ S for the reaction: SO₃( g ) + CaO( s ) → CaSO₄( s ) Δ S in J/mol K for: CaO( s ) = 40, SO₃( g ) = 256.6, CaSO₄( s ) = 107

The randomness of a system may be described as its:

Two 6.5 L flasks are joined by a 150 mL tube with a stop cock. If 0.25 moles of nitrogen are held in the left flask and the right flask is empty, what happens to the entropy of the system upon opening the valve between the flasks?

All exothermic processes are spontaneous

Consider the combustion of ethane (C₂H₆) : C₂H₆( g ) + O₂( g ) → CO₂( g ) + H₂O( l ) If Δ G ° (in kJ/mol) for: C₂H₆( g ) = − 32.9, O₂( g ) = 0, CO₂( g ) = − 394.4, and H₂O( l ) = − 237.2; calculate Δ G ° for the reaction.

According to the Second Law of Thermodynamics, the entropy of the universe must ____ for a spontaneous process?

Without detailed calculations, predict the sign of Δ S for the system for: Mg( s ) + O₂( g ) → MgO( s )

Calculate Δ S for the reaction: 2 SO₃( g ) → 2 SO₂( g ) + O₂( g ) Δ S in J/mol K for: SO₂( g ) = 248.1, SO₃( g ) = 256.6, O₂( g ) = 205.0

The degradation of phosgene (COCl₂) into CO and Cl₂ happens to be non-spontaneous at room temperature and standard state conditions (273 K, 1 atm) . What change in temperature must occur to make this a spontaneous reaction?

The entropy of a system decreases as it moves toward increasing random distributions of particles.

Entropy is a state function.

At what temperature is the entropy of a water sample the highest?

Exam 10: Entropy and the Second Law of Thermodynamics

Which statement best describes the change in entropy during the synthesis of a polymer?

Just because a process is spontaneous does not mean that it happens quickly

Calculate Δ G for the reaction: SO3( g ) + CaO( s ) → CaSO4( s ) Δ G in kJ/mol for: CaO( s ) = − 604.2, SO3( g ) = − 371.1, CaSO4( s ) = − 1320

Exothermic reactions with negative values of S ° are spontaneous at all temperatures.

The use of recycled PET is more cost effective for soda pop bottling than using virgin PET.

Calculate Δ G for the reaction: 2 NO2( g ) → 2 N2( g ) + O2( g ) Δ G in kJ/mol for: NO2( g ) = 51.30

If a 5.0 L flask holds 0.125 moles of nitrogen at STP, what happens to the entropy of the system upon cooling the gas to -75 C?

Calculate Δ S for the reaction: SO3( g ) + CaO( s ) → CaSO4( s ) Δ S in J/mol K for: CaO( s ) = 40, SO3( g ) = 256.6, CaSO4( s ) = 107

The randomness of a system may be described as its:

Two 6.5 L flasks are joined by a 150 mL tube with a stop cock. If 0.25 moles of nitrogen are held in the left flask and the right flask is empty, what happens to the entropy of the system upon opening the valve between the flasks?

All exothermic processes are spontaneous

Consider the combustion of ethane (C2H6) : ​ C2H6( g ) + O2( g ) → CO2( g ) + H2O( l ) ​ If Δ G ° (in kJ/mol) for: C2H6( g ) = − 32.9, O2( g ) = 0, CO2( g ) = − 394.4, and H2O( l ) = − 237.2; calculate Δ G ° for the reaction.

According to the Second Law of Thermodynamics, the entropy of the universe must ____ for a spontaneous process?

Without detailed calculations, predict the sign of Δ S for the system for: Mg( s ) + O2( g ) → MgO( s )

Calculate Δ S for the reaction: 2 SO3( g ) → 2 SO2( g ) + O2( g ) Δ S in J/mol K for: SO2( g ) = 248.1, SO3( g ) = 256.6, O2( g ) = 205.0

The degradation of phosgene (COCl2) into CO and Cl2 happens to be non-spontaneous at room temperature and standard state conditions (273 K, 1 atm) . What change in temperature must occur to make this a spontaneous reaction?

The entropy of a system decreases as it moves toward increasing random distributions of particles.

Entropy is a state function.

At what temperature is the entropy of a water sample the highest?

Calculate Δ G for the reaction: SO₃( g ) + CaO( s ) → CaSO₄( s ) Δ G in kJ/mol for: CaO( s ) = − 604.2, SO₃( g ) = − 371.1, CaSO₄( s ) = − 1320

Calculate Δ G for the reaction: 2 NO₂( g ) → 2 N₂( g ) + O₂( g ) Δ G in kJ/mol for: NO₂( g ) = 51.30

Calculate Δ S for the reaction: SO₃( g ) + CaO( s ) → CaSO₄( s ) Δ S in J/mol K for: CaO( s ) = 40, SO₃( g ) = 256.6, CaSO₄( s ) = 107

Consider the combustion of ethane (C₂H₆) : C₂H₆( g ) + O₂( g ) → CO₂( g ) + H₂O( l ) If Δ G ° (in kJ/mol) for: C₂H₆( g ) = − 32.9, O₂( g ) = 0, CO₂( g ) = − 394.4, and H₂O( l ) = − 237.2; calculate Δ G ° for the reaction.

Without detailed calculations, predict the sign of Δ S for the system for: Mg( s ) + O₂( g ) → MgO( s )

Calculate Δ S for the reaction: 2 SO₃( g ) → 2 SO₂( g ) + O₂( g ) Δ S in J/mol K for: SO₂( g ) = 248.1, SO₃( g ) = 256.6, O₂( g ) = 205.0

The degradation of phosgene (COCl₂) into CO and Cl₂ happens to be non-spontaneous at room temperature and standard state conditions (273 K, 1 atm) . What change in temperature must occur to make this a spontaneous reaction?