Question 1

Which process is the best example of a spontaneous process?

Accepted Answer

A)  CO2 and steam recombine to form an oak tree 
B)  C (graphite) turns to C (diamond) 
C)  hydrogen and oxygen react to form water 
D)  a dorm room cleans itself 
A)  CO2 and steam recombine to form an oak tree 
B)  C (graphite) turns to C (diamond) 
C)  hydrogen and oxygen react to form water 
D)  a dorm room cleans itself

Question 2

Average PET chain lengths tend to shorten during the recycling process.

Accepted Answer

A) True 
 B)False

Question 3

The entropy of a system approaches zero as:

Accepted Answer

A)  it reacts with a halogen gas 
B)  the system surpasses the boiling point of its highest boiling component 
C)  the system approaches absolute zero 
A)  it reacts with a halogen gas 
B)  the system surpasses the boiling point of its highest boiling component 
C)  the system approaches absolute zero

Question 4

Calculate Δ S for the reaction:
2 NO2( g ) → 2 N2( g ) + O2( g ) 
Δ S in J/mol K for: NO2( g ) = 240.0, N2( g )= 191.5, O2( g ) = 205.0

Accepted Answer

A)  +157 J/K 
B)  − 157 J/K 
C)  +108 J/K 
D)  − 480 J/K 
A)  +157 J/K 
B)  − 157 J/K 
C)  +108 J/K 
D)  − 480 J/K

Question 5

Calculate Δ G for the reaction:
2 SO3( g ) → 2 SO2( g ) + O2( g ) 
Δ G in kJ/mol for: SO2( g ) = − 300.2, SO3( g ) = − 371.1

Accepted Answer

A)  − 141.8 
B)  +70.9 
C)  − 70.9 
D)  +141.8 
A)  − 141.8 
B)  +70.9 
C)  − 70.9 
D)  +141.8

Question 6

Consider the combustion of glucose (C6H12O6). This reaction is:

Accepted Answer

A)  spontaneous at all temperatures 
B)  non-spontaneous at all temperatures 
C)  spontaneous towards higher temperatures 
D)  non-spontaneous towards lower temperatures 
A)  spontaneous at all temperatures 
B)  non-spontaneous at all temperatures 
C)  spontaneous towards higher temperatures 
D)  non-spontaneous towards lower temperatures

Question 7

All reactions with a positive Δ S ° are spontaneous regardless of temperature.

Accepted Answer

A) True 
 B)False

Question 8

Converting heat into work decreases entropy because the random motions of molecules become more ordered as a result of the directional aspect of work.

Accepted Answer

A) True 
 B)False

Question 9

Consider the reaction of carbon monoxide with oxygen to produce carbon dioxide.
2 CO( g ) + O2( g ) → 2 CO2( g )  
At what temperature will this reaction be spontaneous according to Gibb's Energy?
Δ H in kJ/mol for: CO( g ) = − 110.5, CO2( g ) = − 393.5
Δ S in J/mol K for: CO( g ) = 197.6, CO2( g ) = 213.6, O2( g ) = 205.0

Accepted Answer

A)  temps above − 63.1 K 
B)  temps below 179.5 K 
C)  temps above 415.8 K 
D)  temps below 3273 K 
A)  temps above − 63.1 K 
B)  temps below 179.5 K 
C)  temps above 415.8 K 
D)  temps below 3273 K

Question 10

Processes that are spontaneous only at lower temperatures are referred to as enthalpy driven reactions.

Accepted Answer

A) True 
 B)False

Which process is the best example of a spontaneous process?

Average PET chain lengths tend to shorten during the recycling process.

The entropy of a system approaches zero as:

Calculate Δ S for the reaction: 2 NO₂( g ) → 2 N₂( g ) + O₂( g ) Δ S in J/mol K for: NO₂( g ) = 240.0, N₂( g )= 191.5, O₂( g ) = 205.0

Calculate Δ G for the reaction: 2 SO₃( g ) → 2 SO₂( g ) + O₂( g ) Δ G in kJ/mol for: SO₂( g ) = − 300.2, SO₃( g ) = − 371.1

Consider the combustion of glucose (C₆H₁₂O₆). This reaction is:

All reactions with a positive Δ S ° are spontaneous regardless of temperature.

Converting heat into work decreases entropy because the random motions of molecules become more ordered as a result of the directional aspect of work.

Processes that are spontaneous only at lower temperatures are referred to as enthalpy driven reactions.

Introduction to Chemistry

Atoms and Molecules

Molecules Moles Chemical Equations

Stoichiometry

Gases

The Periodic Table and Atomic Structure

Chemical Bonding and Molecular Structure

Molecules and Materials

Energy and Chemistry

Chemical Kinetics

Chemical Equilibrium

Electrochemistry

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Exam 10: Entropy and the Second Law of Thermodynamics

Which process is the best example of a spontaneous process?

Average PET chain lengths tend to shorten during the recycling process.

The entropy of a system approaches zero as:

Calculate Δ S for the reaction: 2 NO2( g ) → 2 N2( g ) + O2( g ) Δ S in J/mol K for: NO2( g ) = 240.0, N2( g )= 191.5, O2( g ) = 205.0

Calculate Δ G for the reaction: 2 SO3( g ) → 2 SO2( g ) + O2( g ) Δ G in kJ/mol for: SO2( g ) = − 300.2, SO3( g ) = − 371.1

Consider the combustion of glucose (C6H12O6). This reaction is:

All reactions with a positive Δ S ° are spontaneous regardless of temperature.

Converting heat into work decreases entropy because the random motions of molecules become more ordered as a result of the directional aspect of work.

Processes that are spontaneous only at lower temperatures are referred to as enthalpy driven reactions.

Introduction to Chemistry

Atoms and Molecules

Molecules Moles Chemical Equations

Stoichiometry

Gases

The Periodic Table and Atomic Structure

Chemical Bonding and Molecular Structure

Molecules and Materials

Energy and Chemistry

Chemical Kinetics

Chemical Equilibrium

Electrochemistry

Filters

Calculate Δ S for the reaction: 2 NO₂( g ) → 2 N₂( g ) + O₂( g ) Δ S in J/mol K for: NO₂( g ) = 240.0, N₂( g )= 191.5, O₂( g ) = 205.0

Calculate Δ G for the reaction: 2 SO₃( g ) → 2 SO₂( g ) + O₂( g ) Δ G in kJ/mol for: SO₂( g ) = − 300.2, SO₃( g ) = − 371.1

Consider the combustion of glucose (C₆H₁₂O₆). This reaction is: