Chapter 18 Test Bank Questions

How many types of vibrations does a diatomic molecule exhibit? A) 0 B) 1 C) 2 D) 3 E) 4

1

________ is the pressure required for standard entropy conditions.

1 atm

Which response includes all of the following processes that are accompanied by an increase in entropy? 1. I2(s) → I2(g) 2. 2I(g) → I2(g) 3. 2NH3(g) → N2(g) + 3H2(g) 4. Mg2+(aq) + 2OH-(aq) → Mg(OH)2(s) A) 1, 2 B) 1, 3 C) 3, 4 D) 3 E) 2, 4

1, 3

When a sky diver free-falls through the air, the process is A) nonspontaneous because he is accelerating due to the force applied by gravity. B) nonspontaneous because he is losing potential energy. C) nonspontaneous because he had planned the jump for two weeks. D) spontaneous. E) in equilibrium.

spontaneous.

Which thermodynamic property is a measure of the disorder in the system?

entropy

As the molar mass of a compound increases, the entropy ________. A) decreases B) is constant C) increases

increases

How does the entropy change when a solid is melted?

increases

Predict the sign of ΔS for the reaction 6CO2(g) + 6H2O(g) → C6H12O6(s) + 6O2(g).

negative

Which is necessary for a process to be spontaneous? A) ΔHsys < 0 B) ΔSsys > 0 C) ΔSsurr < 0 D) ΔSuniv > 0 E) ΔGsys = 0

ΔSuniv > 0

If an endothermic process is spontaneous when |TΔS| >|ΔH|, then is ΔS is positive, negative, or equal to zero?

positive

For a process that is spontaneous at high temperatures but not at low temperatures, the sign of ΔH is ________.

postive and > 0

Which is always true for an exothermic process? A) qsys > 0, ΔSsurr < 0 B) qsys < 0, ΔSsurr > 0 C) qsys < 0, ΔSsurr < 0 D) qsys > 0, ΔSsurr > 0 E) w < 0

qsys < 0, ΔSsurr > 0

The ________ law of thermodynamics states that the entropy of the universe in a spontaneous process increases and is constant in equilibrium processes.

second

If a certain process has ΔSuniv > 0 at 25°C, the process may be described as A) exothermic. B) endothermic. C) spontaneous. D) moving rapidly toward equilibrium. E) violating the second law of thermodynamics.

spontaneous.

For a chemical reaction to be spontaneous only at high temperatures, which conditions must be met? A) ΔS° > 0, ΔH° > 0 B) ΔS° > 0, ΔH° < 0 C) ΔS° < 0, ΔH° < 0 D) ΔS° < 0, ΔH° > 0 E) ΔG° > 0

ΔS° > 0, ΔH° > 0

For a chemical reaction to be spontaneous at all temperatures, which conditions must be met? A) ΔS°rxn > 0, ΔH°rxn > 0 B) ΔS°rxn > 0, ΔH°rxn < 0 C) ΔS°rxn< 0, ΔH°rxn < 0 D) ΔS°rxn < 0, ΔH°rxn > 0 E) ΔS°rxn = 0, ΔH°rxn = 0

ΔS°rxn > 0, ΔH°rxn < 0

Which is true for a system at equilibrium? A) ΔS°sys = ΔS°surr B) ΔS°sys = -ΔS°surr C) ΔS°sys = ΔS°surr = 0 D) ΔS°univ > 0 E) ΔS°univ < 0

ΔS°sys = -ΔS°surr

The most probable state is the one with the ________. A) highest energy B) largest number of possible arrangements C) lowest number of possible arrangements D) most symmetry E) highest enthalpy

largest number of possible arrangements

True or False The entropy of vaporization of a compound is always positive.

True

True or False As a chemical reaction proceeds toward equilibrium, the free energy of the system decreases at constant temperature and constant pressure.

True

True or False For a given reaction, a change in the temperature may result in a change in the sign of ΔG.

True

True or False In living systems, thermodynamically favorable reactions provide the free energy needed to drive necessary but thermodynamically unfavorable reactions.

True

How does the entropy change when a gas is liquified?

decreases

Which of the following has ΔG°f = 0 at 25oC? A) H2O(l) B) H2O(g) C) Na(s) D) O3(g) E) O(g)

Na(s)

Predict the sign of ΔS for the reaction O2(g) → 2O(g).

positive

How many types of rotations does a diatomic molecule exhibit? A) 0 B) 1 C) 2 D) 3 E) 4

2

Which reaction has the largest ΔS°? A) 2N2H4(g) → 2NH3(g) + H2(g) + N2(g) B) O2(g) + 2H2(g) → 2H2O(l) C) O2(g) + 2H2(g) → 2H2O(g) D) N2(g) + 3H2(g) → 2NH3(g) E) 2NO(g) → N2O2(g)

2N2H4(g) → 2NH3(g) + H2(g) + N2(g)

According to which scientific law does the entropy of the universe increase in spontaneous processes and remain unchanged in equilibrium processes? A) 1st law of thermodynamics B) 1st law of entropy C) 1st universal law D) 2nd law of thermodynamics E) 3rd law of thermodynamics

2nd law of thermodynamics

How many types of rotations does a bent triatomic molecule exhibit? A) 0 B) 1 C) 2 D) 3 E) 4

3

How many types of vibrations does a bent triatomic molecule exhibit? A) 0 B) 1 C) 2 D) 3 E) 4

3

What term is given to the fact that the entropy of a perfect crystalline solid is zero at absolute zero? A) 1st law of thermodynamics B) 2nd law of thermodynamics C) 3rd law of thermodynamics D) crystalline lattice theory E) absolute crystallinity

3rd law of thermodynamics

Which statement is correct? A) Reaction of ADP and alanine results in ATP in the body. B) A positive ΔG° value means that the reaction is not product favored. C) CO2 is released when ADP reacts with an amino acid. D) Phosphoric acid is one of the products of the reaction of ADP with alanine. E) Hydrolysis of ATP requires NaOH.

A positive ΔG° value means that the reaction is not product favored.

Which statement is correct? A) Oxygen is formed during the metabolism of food. B) The metabolism process results in a positive ΔGo. C) ADP is hydrolyzed to ATP and phosphoric acid in the body. D) A protein is a polymer made of carbohydrate units. E) ATP functions to store energy until it is needed by the body.

ATP functions to store energy until it is needed by the body.

What is the third law of thermodynamics?

At 0 K all perfectly crystalline compounds have S = 0.

Which species will have the lowest absolute entropy at 25°C? A) C2H5OH(l) B) C2H2(g) C) C3H8(g) D) C3H7OH(l) E) C2H6(g)

C2H5OH(l)

Which of the following substances has the greatest entropy per mole? A) O2(g) B) N2(g) C) CO(g) D) CO2(g) E) C4H10(g)

C4H10(g)

Which species will have the greatest absolute entropy at 25°C? A) Ne(g) B) C2H2(g) C) H2O(l) D) C2H5OH(l) E) C4H10(g)

C4H10(g)

Which of these species has the highest entropy (S°) at 25°C? A) CH3OH(l) B) CO(g) C) MgCO3(s) D) H2O(l) E) Si(s)

CO(g)

Which, if any, of the following processes is spontaneous under the specified conditions? A) H2O(l) → H2O(s) at 25°C, 1 atm pressure B) CO2(s) → CO2(g) at 0°C, 1 atm pressure C) 2H2O(g) → 2H2(g) + O2(g) at 25°C, 1 atm pressure D) C(graphite) → C(diamond) at 25°C, 1 atm pressure E) None of these processes is spontaneous.

CO2(s) → CO2(g) at 0°C, 1 atm pressure

Which of the following will decrease the entropy of an inert gas system? A) Increasing the temperature B) Decreasing the volume C) Adding a different inert gas to the system D) Increasing the molar mass E) Decreasing the pressure

Decreasing the volume

What is defined as a measure of the randomness or disorder of a system? A) Gibbs free energy B) Entropy C) Spontaneous process D) Nonspontaneous process E) Enthalpy

Entropy

True or False All elements in their standard state have standard entropies of formation equal to zero.

False

True or False At equilibrium, ΔG° = 0.

False

True or False In a spontaneous process, the entropy of the system always increases.

False

True or False The entropy change ΔS° at 298 K for the reaction NH4Cl(s) →NH3(g) + HCl(g) is negative.

False

True or False The following reaction is spontaneous under standard state conditions at 25°C: AgCl(s) → Ag+ (aq) + Cl- (aq) (ΔG° = 55 kJ/mol)

False

True or False The higher the pressure of a gas sample, the greater is its entropy.

False

True or False The reaction SiO2(s) + Pb(s) → PbO2(s) + Si(s) is spontaneous: ΔG°f (PbO2(s)) = -217 kJ/mol ΔG°f (SiO2(s)) = -856 kJ/mol

False

True or False ΔSuniv = -1 for a spontaneous reaction.

False

Which is a statement of the third law of thermodynamics? A) The entropy of the universe is increasing. B) The entropy of the universe is constant. C) For a perfect crystalline solid, the entropy at T = 0 K is zero. D) The energy of the universe is constant. E) The entropy of all elements are zero.

For a perfect crystalline solid, the entropy at T = 0 K is zero.

Which of the following results in a decrease in the entropy of the system? A) O2(g), 300 K → O2(g), 400 K B) H2O(s), 0°C → H2O(l), 0°C C) N2(g), 25°C → N2(aq), 25°C D) NH3(l), -34.5°C → NH3(g), -34.5°C E) 2H2O2(g) → 2H2O(g) + O2(g)

N2(g), 25°C → N2(aq), 25°C

Which has the largest entropy? A) C (diamond) B) C (graphite) C) H2O(l) D) F2(l) E) O2(g)

O2(g)

ΔSuniverse > 0 is the general condition for a ________ process.

Spontaneous

What is defined as a process that may occur under a specific set of conditions? A) Conditional process B) Nonspontaneous process C) Specified process D) Spontaneous process E) Conditionality law

Spontaneous process

What is defined as the measure of accessible energy levels of a substance at 1 atm? A) Atmospheric disorder B) Atmospheric pressure C) Atmospheric entropy D) Specific pressure E) Standard entropy

Standard entropy

Which statement is correct? A) The standard entropy of a gas phase substance is less than the standard entropy of the same substance in the solid phase. B) For two different substances in the same phase, the substance with the more complex structure has the lower entropy. C) The more highly ordered allotrope of an element has a higher entropy. D) The entropies of elements and compounds are always positive. E) For a monatomic gas, the gas with the lower molar mass has the greater entropy.

The entropies of elements and compounds are always positive.

Which is a statement of the second law of thermodynamics? A) The energy of the universe is constant. B) The entropy of the universe is constant. C) The enthalpy of the universe is constant. D) The energy of the universe is decreasing. E) The entropy of the universe is increasing.

The entropy of the universe is increasing.

Which statement is correct? A) Heating always decreases the entropy of a system. B) The reaction that results in an increase in the number of moles of gas always decreases the entropy of a system. C) The greater number of particles leads to a smaller number of microstates. D) An increase in the temperature decreases all types of molecular motions. E) The solvation process usually leads to an increase in entropy.

The solvation process usually leads to an increase in entropy.

Which of the following is an example of a nonspontaneous process? A) Ice melting at room temperature B) Sodium metal reacting violently with water C) Rusting of iron at room temperature D) A ball rolling downhill E) Water freezing at room temperature

Water freezing at room temperature

A spontaneous endothermic reaction always A) causes the surroundings to get colder. B) bursts into flame. C) requires a spark to initiate it. D) releases heat to the surroundings.

causes the surroundings to get colder.

For a process where a gas condenses to a liquid, the entropy ________.

decreases

A negative sign for ΔG indicates that, at constant T and P, A) the reaction is exothermic. B) the reaction is endothermic. C) the reaction is fast. D) the reaction is spontaneous. E) ΔS of the system must be greater than zero.

the reaction is spontaneous.

Which is the thermodynamic condition for a spontaneous process at constant T and P? A) ΔS > 0 B) ΔS < 0 C) ΔG < 0 D) ΔG > 0 E) ΔG° = 0

ΔG < 0

At constant temperature and pressure, which is the correct relationship between ΔG and other thermodynamic quantities? A) ΔG = ΔH - TΔS B) ΔG = ΔH + TΔS C) ΔG = ΔU - TΔS D) ΔG = -TΔS E) ΔG = q/T

ΔG = ΔH - TΔS

For the process C6H6(l) <-----> C6H6(s) at a temperature above the freezing point of C6H6, A) ΔS is positive. B) ΔH is positive. C) ΔG is positive. D) ΔG = O.

ΔG is positive.

At temperatures below 273 K, it is observed that liquid water spontaneously freezes to form solid ice. What must be true about the entropy changes of the system and surroundings for this process? A) ΔSsys > 0, ΔSsurr > 0 B) ΔSsys < 0, ΔSsurr > 0 C) ΔSsys < 0, ΔSsurr < 0 D) ΔSsys > 0, ΔSsurr < 0 E) ΔSsys = 0, ΔSsurr > 0

ΔSsys < 0, ΔSsurr > 0