Question 1

If the ΔGf° of CuO is equal to -129.7 kJ/mol, what is the ΔG° for the decomposition of CuO to metallic copper and oxygen gas?

Accepted Answer

A)  234.3 kJ 
B)  76.9 kJ 
C)  197.2 kJ 
D)  326.5 kJ 
E)  129.7 kJ 
A)  234.3 kJ 
B)  76.9 kJ 
C)  197.2 kJ 
D)  326.5 kJ 
E)  129.7 kJ E

Question 2

Which of the following best defines a state function?

Accepted Answer

A)  It is the property of a system whose magnitude depends on the pathway used to go from one state to another. 
B)  It is the property of a system whose magnitude depends on only the present state of the system, not its previous history. 
C)  It is the property of a system whose magnitude depends on the work done in the past and on how the equilibrium state is reached. 
D)  It is the property of a system whose magnitude depends on only the previous history of the system. 
E)  It is the property of a system whose magnitude is independent of the equilibrium state of the system. 
A)  It is the property of a system whose magnitude depends on the pathway used to go from one state to another. 
B)  It is the property of a system whose magnitude depends on only the present state of the system, not its previous history. 
C)  It is the property of a system whose magnitude depends on the work done in the past and on how the equilibrium state is reached. 
D)  It is the property of a system whose magnitude depends on only the previous history of the system. 
E)  It is the property of a system whose magnitude is independent of the equilibrium state of the system. B

Question 3

Why are equilibrium constants dependent on temperature?

Accepted Answer

In the relation, $$\ln K = - \frac { \Delta H ^ { \circ } } { R T } + \frac { \Delta S ^ { \circ } } { R }$$ , assuming ΔH° and ΔS° are temperature independent, for an exothermic reaction (ΔH° < 0), the magnitude of K decreases with increasing temperature, whereas for an endothermic reaction (ΔH° > 0), the magnitude of K increases with increasing temperature. Because heat is produced in an exothermic reaction, adding heat (by increasing the temperature) will shift the equilibrium to the left, favoring the reactants and decreasing the magnitude of K. Conversely, because heat is consumed in an endothermic reaction, adding heat will shift the equilibrium to the right, favoring the products and increasing the magnitude of K. If we know the value of K at a given temperature and the value of ΔH° for a reaction, we can estimate the value of K at any other temperature.

Question 4

The absolute entropy of a substance tends to decrease with increasing molecular complexity.

Accepted Answer

A) True 
 B)False

Question 5

If a force of 80.0 N acts on the piston, by what distance should the piston move in order to perform 5.00×102 J of work?

Accepted Answer

A)  6.25 m 
B)  11.5 m 
C)  2.48 m 
D)  14.9 m 
E)  17.5 m 
A)  6.25 m 
B)  11.5 m 
C)  2.48 m 
D)  14.9 m 
E)  17.5 m

Question 6

Explain standard free-energy change and standard free energy of formation.

Accepted Answer

The standard free-energy change (ΔG°) is

Question 7

At 25°C, for the reaction $2 \mathrm { H } _ { 2 } ( \mathrm {~g} ) + \mathrm { O } _ { 2 } ( \mathrm {~g} ) f \quad 2 \mathrm { H } _ { 2 } \mathrm { O } ( \mathrm { l } )$ , the standard enthalpy change (?H°) is ?285.8 kJ/mol, and the absolute entropies of the products and reactants are S°(H2O) = 70.00 J/(mol·K), S°(O2) = 205.2 J/(mol·K), and S°(H2) = 130.7 J/(mol·K). What is the standard free-energy change for the reaction?

Accepted Answer

A)  278.6 kJ/mol 
B)  -188.4 kJ/mol 
C)  -249.7 kJ/mol 
D)  359.8 kJ/mol 
E)  -313.4 kJ/mol 
A)  278.6 kJ/mol 
B)  -188.4 kJ/mol 
C)  -249.7 kJ/mol 
D)  359.8 kJ/mol 
E)  -313.4 kJ/mol

Question 8

Work done in an irreversible process is always equal to or greater than work done in a corresponding reversible process.

Accepted Answer

A) True 
 B)False

Question 9

ΔE for a process is the same whether that process is carried out in a reversible manner or an irreversible one.

Accepted Answer

A) True 
 B)False

Question 10

If the enthalpy of fusion of ice is 6.01 kJ/mol, what is the entropy of fusion of ice?

Accepted Answer

A)  11.3 $\mathrm { J } / ( \mathrm { mol } \cdot \mathrm { K } )$
  
B)  6.75 $\mathrm { J } / ( \mathrm { mol } \cdot \mathrm { K } )$ 
C)  22.0 $\mathrm { J } / ( \mathrm { mol } \cdot \mathrm { K } )$ 
D)  17.2 $\mathrm { J } / ( \mathrm { mol } \cdot \mathrm { K } )$ 
E)  29.6 $\mathrm { J } / ( \mathrm { mol } \cdot \mathrm { K } )$ 
A)  11.3 $\mathrm { J } / ( \mathrm { mol } \cdot \mathrm { K } )$
  
B)  6.75 $\mathrm { J } / ( \mathrm { mol } \cdot \mathrm { K } )$ 
C)  22.0 $\mathrm { J } / ( \mathrm { mol } \cdot \mathrm { K } )$ 
D)  17.2 $\mathrm { J } / ( \mathrm { mol } \cdot \mathrm { K } )$ 
E)  29.6 $\mathrm { J } / ( \mathrm { mol } \cdot \mathrm { K } )$

Question 11

A disordered system has higher entropy than an ordered system.

Accepted Answer

A) True 
 B)False

Question 12

When a reaction involves only solids, liquids, or liquid solutions, the change in enthalpy is equal to the change in internal energy.

Accepted Answer

A) True 
 B)False

Question 13

The process of condensing a vapor to form a liquid must be accompanied by an increase in the entropy of the system.

Accepted Answer

A) True 
 B)False

Question 14

Soft crystalline substances have higher entropies because of increased molecular motion and disorder.

Accepted Answer

A) True 
 B)False

Question 15

Assuming 30% efficiency in the conversion of the released energy to ATP, how many molecules of ATP can be synthesized by the combustion of one molecule of glucose to form CO2 and H2O? Given: ΔGf°: −910.4 kJ/mol for glucose, −394.4 kJ/mol for CO2(g), and −237.1 kJ/mol for H2O(l) , and ΔG°′ for the hydrolysis of ATP is −34.54 kJ/mol.

Accepted Answer

A)  14 ATP/glucose 
B)  57 ATP/glucose 
C)  43 ATP/glucose 
D)  32 ATP/glucose 
E)  25 ATP/glucose 
A)  14 ATP/glucose 
B)  57 ATP/glucose 
C)  43 ATP/glucose 
D)  32 ATP/glucose 
E)  25 ATP/glucose

Question 16

_____ is the combustion of a carbon compound such as glucose to CO2 and water.

Accepted Answer

Question 17

In a thermodynamic sense, a living cell can be viewed as a low-entropy system that is in equilibrium with its surroundings and is incapable of replicating itself.

Accepted Answer

A) True 
 B)False

Question 18

A reaction in which a single species is both oxidized and reduced is called a(n) _____ reaction.

Accepted Answer

The answer of A reaction in which a single species...

Question 19

_____ is the thermodynamic property of all substances that is proportional to their degree of disorder.

Accepted Answer

The answer of _____ is the thermodynamic property of all...

Question 20

Work done by a system on its surroundings has a positive sign because it results in a transfer of energy to a system from its surroundings.

Accepted Answer

A) True 
 B)False

Exam 18: Chemical Thermodynamics

If the ΔGf° of CuO is equal to -129.7 kJ/mol, what is the ΔG° for the decomposition of CuO to metallic copper and oxygen gas?

Which of the following best defines a state function?

Why are equilibrium constants dependent on temperature?

The absolute entropy of a substance tends to decrease with increasing molecular complexity.

If a force of 80.0 N acts on the piston, by what distance should the piston move in order to perform 5.00×102 J of work?

Explain standard free-energy change and standard free energy of formation.

Work done in an irreversible process is always equal to or greater than work done in a corresponding reversible process.

ΔE for a process is the same whether that process is carried out in a reversible manner or an irreversible one.

If the enthalpy of fusion of ice is 6.01 kJ/mol, what is the entropy of fusion of ice?

A disordered system has higher entropy than an ordered system.

When a reaction involves only solids, liquids, or liquid solutions, the change in enthalpy is equal to the change in internal energy.

The process of condensing a vapor to form a liquid must be accompanied by an increase in the entropy of the system.

Soft crystalline substances have higher entropies because of increased molecular motion and disorder.

_____ is the combustion of a carbon compound such as glucose to CO2 and water.

In a thermodynamic sense, a living cell can be viewed as a low-entropy system that is in equilibrium with its surroundings and is incapable of replicating itself.

A reaction in which a single species is both oxidized and reduced is called a(n) _____ reaction.

_____ is the thermodynamic property of all substances that is proportional to their degree of disorder.

Work done by a system on its surroundings has a positive sign because it results in a transfer of energy to a system from its surroundings.

Introduction to Chemistry

Molecules, Ions, and Chemical Formulas

Chemical Reactions

Reactions in Aqueous Solution

Energy Changes in Chemical Reactions

The Structure of Atoms

The Periodic Table and Periodic Trends

Ionic Versus Covalent Bonding

Molecular Geometry and Covalent Bonding Models

Gases

Liquids

Solids

Solutions

Chemical Kinetics

Chemical Equilibrium

Aqueous Acidbase Equilibriums

Solubility and Complexation Equilibriums

Electrochemistry

Nuclear Chemistry

Periodic Trends and the S-Block Elements

The P-Block Elements

The D-Block Elements

Organic Compounds

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If the ΔG_f° of CuO is equal to -129.7 kJ/mol, what is the ΔG° for the decomposition of CuO to metallic copper and oxygen gas?

If a force of 80.0 N acts on the piston, by what distance should the piston move in order to perform 5.00×10² J of work?

_____ is the combustion of a carbon compound such as glucose to CO₂ and water.