Question 1

If two reactions are coupled, then

Accepted Answer

A)  A product of one reaction is a reactant of the other, and the overall process is reactant-favored. 
B)  A product of one reaction is a reactant of the other, and the overall process is product-favored. 
C)  The heat released from an exothermic reaction is used in an endothermic reaction. 
D)  A product-favored reaction supplies the activation energy for another reaction. 
E)  The Gibbs free energy released from a product-favored reaction is released to the surroundings, causing an increase in entropy for a second reaction. 
A)  A product of one reaction is a reactant of the other, and the overall process is reactant-favored. 
B)  A product of one reaction is a reactant of the other, and the overall process is product-favored. 
C)  The heat released from an exothermic reaction is used in an endothermic reaction. 
D)  A product-favored reaction supplies the activation energy for another reaction. 
E)  The Gibbs free energy released from a product-favored reaction is released to the surroundings, causing an increase in entropy for a second reaction.

Question 2

Which set of conditions describes a reaction that is least likely to proceed?

Accepted Answer

A)  endothermic, decreasing entropy, high activation energy 
B)  exothermic, decreasing entropy, high activation energy 
C)  exothermic, increasing entropy, high activation energy 
D)  exothermic, increasing entropy, low activation energy 
E)  endothermic, decreasing entropy, low activation energy 
A)  endothermic, decreasing entropy, high activation energy 
B)  exothermic, decreasing entropy, high activation energy 
C)  exothermic, increasing entropy, high activation energy 
D)  exothermic, increasing entropy, low activation energy 
E)  endothermic, decreasing entropy, low activation energy

Question 3

The value of the equilibrium constant for a reaction is 2.65 × 10-6 at 45$\circ$C. Calculate the value of DG$\circ$rxn at this temperature.

Accepted Answer

A)  +47.4 kJ 
B)  +34.0 kJ 
C)  +14.8 kJ 
D)  +335 kJ 
E)  -14.8 kJ 
A)  +47.4 kJ 
B)  +34.0 kJ 
C)  +14.8 kJ 
D)  +335 kJ 
E)  -14.8 kJ

Question 4

Use the data given to calculate the value of K for the reaction at 25$\circ$C.

Accepted Answer

A)  6.61 × 10-14 
B)  3.41 × 10-12 
C)  4.75 × 10-12 
D)  1.76 × 10-10 
E)  5.69 × 109 
A)  6.61 × 10-14 
B)  3.41 × 10-12 
C)  4.75 × 10-12 
D)  1.76 × 10-10 
E)  5.69 × 109

Question 5

Which statement is false?

Accepted Answer

A)  energy will disperse unless it is hindered from doing so 
B)  energy will not disperse unless it is forced to do so 
C)  energy has a higher probability of being spread out over many molecules than of being concentrated in a few 
D)  energy is dispersed when a system of atoms or molecules expands to occupy a larger volume 
E)  gases expanding into larger volumes illustrate energy dispersal 
A)  energy will disperse unless it is hindered from doing so 
B)  energy will not disperse unless it is forced to do so 
C)  energy has a higher probability of being spread out over many molecules than of being concentrated in a few 
D)  energy is dispersed when a system of atoms or molecules expands to occupy a larger volume 
E)  gases expanding into larger volumes illustrate energy dispersal

Question 6

A reaction is product-favored when

Accepted Answer

A)  K$\circ$ $\circ$ > 0 
B)  K$\circ$ > 1 and DG$\circ$ $\circ$= 1 and DG$\circ$ = 0 
D)  K$\circ$= 0 and DG$\circ$ = 0 
E)  K$\circ$ $\circ$ = 0 
A)  K$\circ$ $\circ$ > 0 
B)  K$\circ$ > 1 and DG$\circ$ $\circ$= 1 and DG$\circ$ = 0 
D)  K$\circ$= 0 and DG$\circ$ = 0 
E)  K$\circ$ $\circ$ = 0

Question 7

It is possible for a substance, with respect to a given reaction, to

Accepted Answer

A)  be kinetically and thermodynamically stable. 
B)  be kinetically stable but not thermodynamically stable. 
C)  be thermodynamically stable but not kinetically stable. 
D)  fall in either category a or category b. 
E)  fall in either category a or category c. 
A)  be kinetically and thermodynamically stable. 
B)  be kinetically stable but not thermodynamically stable. 
C)  be thermodynamically stable but not kinetically stable. 
D)  fall in either category a or category b. 
E)  fall in either category a or category c.

Question 8

A slight change in temperature can change the directionality of a reaction when

Accepted Answer

A)  T = DH$\circ$rxn / DS$\circ$rxn 
B)  T = DS$\circ$rxn / DH$\circ$rxn 
C)  DG$\circ$rxn > 0 
D)  DG$\circ$rxn = 0 
E)  DG$\circ$rxn is a much larger positive value than DH$\circ$rxn 
A)  T = DH$\circ$rxn / DS$\circ$rxn 
B)  T = DS$\circ$rxn / DH$\circ$rxn 
C)  DG$\circ$rxn > 0 
D)  DG$\circ$rxn = 0 
E)  DG$\circ$rxn is a much larger positive value than DH$\circ$rxn

Question 9

At constant T and P, in which of the following situations will the reaction always be product-favored?

Accepted Answer

A)  DH > 0 and DS  0 and DS > 0 
C)  DH  0 
E)  there are no examples of reactions that are always product-favored 
A)  DH > 0 and DS  0 and DS > 0 
C)  DH  0 
E)  there are no examples of reactions that are always product-favored

Question 10

Use the data given to calculate the value of DG$\circ$rxn for the reaction at 25$\circ$C

Accepted Answer

A)  -75.2 kJ 
B)  -55.7 kJ 
C)  +32.5 kJ 
D)  +55.7 kJ 
E)  +75.2 kJ 
A)  -75.2 kJ 
B)  -55.7 kJ 
C)  +32.5 kJ 
D)  +55.7 kJ 
E)  +75.2 kJ

Question 11

Which has the highest entropy?

Accepted Answer

A)  H2O(g) at 150$\circ$C 
B)  H2O(g) at 100$\circ$C 
C)  H2O(l) at 100$\circ$C 
D)  H2O(l) at 4$\circ$C (the temperature of maximum density) 
E)  H2O(s) at -50$\circ$C 
A)  H2O(g) at 150$\circ$C 
B)  H2O(g) at 100$\circ$C 
C)  H2O(l) at 100$\circ$C 
D)  H2O(l) at 4$\circ$C (the temperature of maximum density) 
E)  H2O(s) at -50$\circ$C

Question 12

How many of the following processes could be described as product-favored: dissolving the first spoonful of sugar in a cup of hot coffee; alcohol separating from a beer sample at 5$\circ$C; dissolving the ninth spoonful of sugar in a cup of hot coffee; sediment settling out of an muddy water sample?

Accepted Answer

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

Question 13

A specific chemical reaction must be product-favored if

Accepted Answer

A) DG$\circ$rxn > 0 B) DG$\circ$rxn = 0 C) DG$\circ$rxn $\circ$rxn > 0 and DS$\circ$rxn $\circ$rxn $\circ$rxn < 0 A) DG$\circ$rxn > 0 B) DG$\circ$rxn = 0 C) DG$\circ$rxn $\circ$rxn > 0 and DS$\circ$rxn $\circ$rxn $\circ$rxn < 0

Question 14

Which has the lowest entropy at a given temperature?

Accepted Answer

A)  H2(g) 
B)  O2(g) 
C)  H2O(g) 
D)  H2O(l) 
E)  H2O(s) 
A)  H2(g) 
B)  O2(g) 
C)  H2O(g) 
D)  H2O(l) 
E)  H2O(s)

Question 15

Which statement is correct?

Accepted Answer

A)  A product-favored process requires a continuous input of energy to continue 
B)  A product-favored process may start on its own without much initial energy input 
C)  A product-favored process, when run in reverse, is also product-favored 
D)  Once started, a reactant-favored process will continue on its own 
E)  The term non-spontaneous is sometimes used to describe a product-favored process 
A)  A product-favored process requires a continuous input of energy to continue 
B)  A product-favored process may start on its own without much initial energy input 
C)  A product-favored process, when run in reverse, is also product-favored 
D)  Once started, a reactant-favored process will continue on its own 
E)  The term non-spontaneous is sometimes used to describe a product-favored process

Question 16

The boiling point of tin is 232$\circ$C. The heat of vaporization of tin at its boiling point is 247 kJ. The entropy of vaporization is

Accepted Answer

A)  2045 J/K. 
B)  1065 J/K. 
C)  939 J/K. 
D)  489 J/K. 
E)  2.04 J/K. 
A)  2045 J/K. 
B)  1065 J/K. 
C)  939 J/K. 
D)  489 J/K. 
E)  2.04 J/K.

If two reactions are coupled, then

Which set of conditions describes a reaction that is least likely to proceed?

The value of the equilibrium constant for a reaction is 2.65 × 10^-6 at 45^$\circ$C. Calculate the value of DG^$\circ$_rxn at this temperature.

Use the data given to calculate the value of K for the reaction at 25^$\circ$C. $Use the data given to calculate the value of K for the reaction at 25<sup> \circ </sup>C.$ $Use the data given to calculate the value of K for the reaction at 25<sup> \circ </sup>C.$

Which statement is false?

A reaction is product-favored when

It is possible for a substance, with respect to a given reaction, to

A slight change in temperature can change the directionality of a reaction when

At constant T and P, in which of the following situations will the reaction always be product-favored?

Which has the highest entropy?

A specific chemical reaction must be product-favored if

Which has the lowest entropy at a given temperature?

Which statement is correct?

The boiling point of tin is 232^$\circ$C. The heat of vaporization of tin at its boiling point is 247 kJ. The entropy of vaporization is

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Exam 17: Thermodynamics: Directionality of Chemical Reactions

If two reactions are coupled, then

Which set of conditions describes a reaction that is least likely to proceed?

The value of the equilibrium constant for a reaction is 2.65 × 10-6 at 45 ∘\circ∘ C. Calculate the value of DG ∘\circ∘ rxn at this temperature.

Use the data given to calculate the value of K for the reaction at 25 ∘\circ∘ C.

Which statement is false?

A reaction is product-favored when

It is possible for a substance, with respect to a given reaction, to

A slight change in temperature can change the directionality of a reaction when

At constant T and P, in which of the following situations will the reaction always be product-favored?

Use the data given to calculate the value of DG ∘\circ∘ rxn for the reaction at 25 ∘\circ∘ C

Which has the highest entropy?

A specific chemical reaction must be product-favored if

Which has the lowest entropy at a given temperature?

Which statement is correct?

The boiling point of tin is 232 ∘\circ∘ C. The heat of vaporization of tin at its boiling point is 247 kJ. The entropy of vaporization is

The Nature of Chemistry

Atoms and Elements

Chemical Compounds

Quantities of Reactants and Products

Chemical Reactions

Energy and Chemical Reactions

Electron Configurations and the Periodic Table

Covalent Bonding

Molecular Structure

Gases and the Atmosphere

Liquids, Solids, and Materials

Chemical Kinetics: Rates of Reactions

Chemical Equilibrium

The Chemistry of Solutes and Solutions

Acids and Bases

Additional Aqueous Equilibria

Electrochemistry and Its Applications

Nuclear Chemistry

Filters

The value of the equilibrium constant for a reaction is 2.65 × 10^-6 at 45^$\circ$C. Calculate the value of DG^$\circ$_rxn at this temperature.

Use the data given to calculate the value of K for the reaction at 25^$\circ$C. $Use the data given to calculate the value of K for the reaction at 25<sup> \circ </sup>C.$ $Use the data given to calculate the value of K for the reaction at 25<sup> \circ </sup>C.$

The boiling point of tin is 232^$\circ$C. The heat of vaporization of tin at its boiling point is 247 kJ. The entropy of vaporization is