Question 1

The standard molar free energies of formation of NO2(g)  and N2O4(g)  at 25°C are 51.84 and 98.28 kJ/mol, respectively. What is the value of Kp (in atm)  for the reaction written as follows at 25°C?
2NO2 2(g)  and N2O4(g)  at 25°C are 51.84 and 98.28 kJ/mol, respectively. What is the value of Kp (in atm)  for the reaction written as follows at 25°C? 2NO2  N2O4 A)  8.84 B)  1.17 × 104 C)  1.37 × 108 D)  7.31 × 10-9 E)  0.113" class="answers-bank-image d-inline" rel="preload" >N2O4

Accepted Answer

A)   8.84
B)   1.17 × 104
C)   1.37 × 108
D)   7.31 × 10-9
E)   0.113F) None of the above
G) D) and E)

Question 2

When a stable diatomic molecule spontaneously forms from its atoms, what are the signs of ΔH°, ΔS°, and ΔG°, respectively?

Accepted Answer

A)   + + +
B)   - - +
C)   - + +
D)   + - -
E)   - - -F) A) and D)
G) A) and C)

Question 3

A gas expands isothermally and irreversibly.
-ΔS is

Accepted Answer

A)   less than zero.
B)   More information is needed.
C)   greater than zero.
D)   equal to zero.E) All of the above
F) B) and D)

Question 4

In which case must a reaction be spontaneous at all temperatures?

Accepted Answer

A)   ΔS = 0, ΔH is positive
B)   ΔH is negative, ΔS is positive
C)   ΔH = 0, ΔS is negative
D)   ΔH is positive, ΔS is positive
E)   none of theseF) C) and E)
G) B) and D)

Question 5

As O2(l)  is cooled at 1 atm, it freezes at 54.5 K to form Solid I. At a lower temperature, Solid I rearranges to Solid II, which has a different crystal structure. Thermal measurements show that ΔH for the I → II phase transition is -743.1 J/mol and that ΔS for the same transition is -17.0 J/K mol. At what temperature are Solids I and II in equilibrium?

Accepted Answer

A)   43.7 K
B)   2.06 K
C)   53.4 K
D)   31.5 K
E)   They can never be in equilibrium because they are both solids.F) A) and E)
G) A) and C)

Question 6

Calculate the entropy change when 5.00 mol of a monatomic ideal gas is cooled from 135°C to 85°C at 1 atm.

Accepted Answer

A)   -48.9 J/K
B)   -13.6 J/K
C)   -250.0 J/K
D)   -9.62 J/K
E)   -2.74 J/KF) A) and E)
G) C) and D)

Question 7

The constant that connects the entropy of a system to the number of microstates is

Accepted Answer

A)   B 
E)   B and C" class="answers-bank-image d-inline" rel="preload" >
B)   B 
E)   B and C" class="answers-bank-image d-inline" rel="preload" >
C)   R
D)   kB
E)   B and CF) C) and D)
G) All of the above

Question 8

One mole of an ideal gas is compressed isothermally at 607.4 K from 5.60 atm to 8.90 atm. If the process is carried out in two irreversible steps (intermediate step at P = 7.00 atm) , calculate the following.ΔS

Accepted Answer

A)   0 J/K
B)   -3.85 J/K
C)   3.85 J/K
D)   -2.34 J/K
E)   2.34 J/KF) B) and E)
G) B) and C)

Question 9

In which reaction is ΔS° expected to be positive?

Accepted Answer

A)   H2O(1)  →H2O(s) 
B)   2O2(g)  + 2SO(g)  → 2SO3(g) 
C)   CH3OH(g)  + (3/2) O2(g)  → CO2(g)  + 2H2O(l) 
D)   I2(g)  → I2(s) 
E)   none of theseF) None of the above
G) All of the above

Question 10

A gas expands isothermally and irreversibly.
-ΔG is

Accepted Answer

A)   More information is needed.
B)   less than zero.
C)   greater than zero.
D)   equal to zero.E) B) and C)
F) B) and D)

Question 11

The process H2O(g)  → H2O(l)  takes place at 1 atm and 95°C.
-6.00 mol of a monatomic ideal gas is cooled from 254°C to 24°C at constant volume. Calculate ΔS.

Accepted Answer

A)   -31.1 J/K
B)   -42.9 J/K
C)   -1.77 × 102 J/K
D)   -18.6 J/K
E)   -71.5 J/KF) C) and D)
G) B) and E)

Question 12

The process H2O(g)  → H2O(l)  takes place at 1 atm and 95°C.
-Calculate ΔS for cooling 2.60 mol of an ideal monatomic gas from 88°C to 39°C at constant volume.

Accepted Answer

A)   -1.82 J/K
B)   -17.6 J/K
C)   -3.15 J/K
D)   -4.73 J/K
E)   -26.4 J/KF) A) and D)
G) A) and C)

Question 13

The standard free energy of formation of nitric oxide, NO, at 1000. K (roughly the temperature in an automobile engine during ignition)  is 78 kJ/mol. Calculate the equilibrium constant for the reaction
N2(g)  + O2(g)  2(g)  + O2(g)   2NO(g)  At 1000. K. A)  4.3 × 10-10 B)  8.4 × 10-5 C)  0.99 D)  1.8 × 10-19 E)  7.1 × 10-9" class="answers-bank-image d-inline" rel="preload" >2NO(g) 
At 1000. K.

Accepted Answer

A)   4.3 × 10-10
B)   8.4 × 10-5
C)   0.99
D)   1.8 × 10-19
E)   7.1 × 10-9F) A) and C)
G) B) and E)

Question 14

Consider the process A(l)   A(s) . Which direction favors positional randomness?

Accepted Answer

A)   to the left
B)   neither
C)   It depends on the temperature.
D)   to the rightE) A) and B)
F) A) and C)

Question 15

One mole of an ideal gas expands isothermally and reversibly at 0°C. The pressure on 1 mol of an ideal monatomic gas changes from 100.0 atm to 1.00 atm.
-Calculate q.

Accepted Answer

A)   -225 kJ
B)   0
C)   -10.5 kJ
D)   10.5 kJ
E)   225 kJF) D) and E)
G) C) and D)

Question 16

Given that S° = 131 J/Kmol for H2(g) , estimate the value of ΔS° for the reaction 2(g) , estimate the value of ΔS° for the reaction   A)  0 B)  131 J/K C)  -131 J/K D)  262 J/K E)  -262 J/K" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   0
B)   131 J/K
C)   -131 J/K
D)   262 J/K
E)   -262 J/KF) A) and B)
G) D) and E)

Question 17

​Which of the following statements is/are true of work in reversible and irreversible processes?
1)  Achieving the maximum work available from a spontaneous process can occur only via a hypothetical pathway. 
2)  In any real cyclic process, work is changed to heat in the surrounding, and the entropy of the universe increases. 
3)  Achieving the maximum work available from a spontaneous process can occur via a real pathway.

Accepted Answer

A)   1 only​
B)   3 only
C)   1 and 2
D)   2 and 3
E)   1 and 3F) A) and B)
G) B) and D)

Question 18

At 699 K, ΔG° = -23.25 kJ for the reaction H2(g)  + I2(g)  2(g)  + I2(g)    2HI(g) . Calculate ΔG for this reaction if the reagents are both supplied at 10.0 atm pressure and the product is at 1.00 atm pressure. A)  +50.0 kJ B)  +36.6 kJ C)  -36.6 kJ D)  -3.5 kJ E)  -50.0 kJ" class="answers-bank-image d-inline" rel="preload" > 2HI(g) . Calculate ΔG for this reaction if the reagents are both supplied at 10.0 atm pressure and the product is at 1.00 atm pressure.

Accepted Answer

A)   +50.0 kJ
B)   +36.6 kJ
C)   -36.6 kJ
D)   -3.5 kJ
E)   -50.0 kJF) B) and C)
G) A) and B)

Question 19

Assume that the reaction
CO(g)  + H2O(g)  2O(g)   CO2(g)  + H2(g)  Occurs in an mixture of ideal gases. At 700 K, Kp = 5.10. At this temperature, what is ΔG°? A)  0 kJ B)  29.7 kJ C)  -9.48 kJ D)  -4.12 kJ E)  9.48 kJ" class="answers-bank-image d-inline" rel="preload" >CO2(g)  + H2(g) 
Occurs in an mixture of ideal gases. At 700 K, Kp = 5.10. At this temperature, what is ΔG°?

Accepted Answer

A)   0 kJ
B)   29.7 kJ
C)   -9.48 kJ
D)   -4.12 kJ
E)   9.48 kJF) A) and D)
G) None of the above

Question 20

What is the value of ΔH for this dissociation reaction?

Accepted Answer

A)   26.8 kJ
B)   -122.1 kJ
C)   112.4 kJ
D)   122.1 kJ
E)   none of theseF) A) and C)
G) All of the above

Exam 10: Spontaneity, Entropy, and Free Energy

The standard molar free energies of formation of NO₂(g) and N₂O₄(g) at 25°C are 51.84 and 98.28 kJ/mol, respectively. What is the value of K_p (in atm) for the reaction written as follows at 25°C? 2NO₂ N₂O₄

Correct Answer
verified

The constant that connects the entropy of a system to the number of microstates is

Correct Answer
verified

The process H₂O(g) → H₂O(l) takes place at 1 atm and 95°C. -Calculate ΔS for cooling 2.60 mol of an ideal monatomic gas from 88°C to 39°C at constant volume.

Correct Answer
verified

Correct Answer
verified

Calculate the entropy change when 5.00 mol of a monatomic ideal gas is cooled from 135°C to 85°C at 1 atm.

Correct Answer
verified

Consider the process A(l) A(s) . Which direction favors positional randomness?

Correct Answer
verified

When a stable diatomic molecule spontaneously forms from its atoms, what are the signs of ΔH°, ΔS°, and ΔG°, respectively?

Correct Answer
verified

What is the value of ΔH for this dissociation reaction?

Correct Answer
verified

Correct Answer
verified

Assume that the reaction CO(g) + H₂O(g) CO₂(g) + H₂(g) Occurs in an mixture of ideal gases. At 700 K, K_p = 5.10. At this temperature, what is ΔG°?

Correct Answer
verified

In which case must a reaction be spontaneous at all temperatures?

Correct Answer
verified

One mole of an ideal gas is compressed isothermally at 607.4 K from 5.60 atm to 8.90 atm. If the process is carried out in two irreversible steps (intermediate step at P = 7.00 atm) , calculate the following.ΔS

Correct Answer
verified

A gas expands isothermally and irreversibly. -ΔG is

Correct Answer
verified

The process H₂O(g) → H₂O(l) takes place at 1 atm and 95°C. -6.00 mol of a monatomic ideal gas is cooled from 254°C to 24°C at constant volume. Calculate ΔS.

Correct Answer
verified

One mole of an ideal gas expands isothermally and reversibly at 0°C. The pressure on 1 mol of an ideal monatomic gas changes from 100.0 atm to 1.00 atm. -Calculate q.

Correct Answer
verified

Given that S° = 131 J/Kmol for H₂(g) , estimate the value of ΔS° for the reaction

Correct Answer
verified

The standard free energy of formation of nitric oxide, NO, at 1000. K (roughly the temperature in an automobile engine during ignition) is 78 kJ/mol. Calculate the equilibrium constant for the reaction N₂(g) + O₂(g) 2NO(g) At 1000. K.

Correct Answer
verified

At 699 K, ΔG° = -23.25 kJ for the reaction H₂(g) + I₂(g) 2HI(g) . Calculate ΔG for this reaction if the reagents are both supplied at 10.0 atm pressure and the product is at 1.00 atm pressure.

Correct Answer
verified

In which reaction is ΔS° expected to be positive?

Correct Answer
verified

A gas expands isothermally and irreversibly. -ΔS is

Correct Answer
verified

Exam 10: Spontaneity, Entropy, and Free Energy

The standard molar free energies of formation of NO2(g) and N2O4(g) at 25°C are 51.84 and 98.28 kJ/mol, respectively. What is the value of Kp (in atm) for the reaction written as follows at 25°C? 2NO2 N2O4

Correct AnswerverifiedShow Answer

The constant that connects the entropy of a system to the number of microstates is

Correct AnswerverifiedShow Answer

The process H2O(g) → H2O(l) takes place at 1 atm and 95°C. -Calculate ΔS for cooling 2.60 mol of an ideal monatomic gas from 88°C to 39°C at constant volume.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Calculate the entropy change when 5.00 mol of a monatomic ideal gas is cooled from 135°C to 85°C at 1 atm.

Correct AnswerverifiedShow Answer

Consider the process A(l) A(s) . Which direction favors positional randomness?

Correct AnswerverifiedShow Answer

When a stable diatomic molecule spontaneously forms from its atoms, what are the signs of ΔH°, ΔS°, and ΔG°, respectively?

Correct AnswerverifiedShow Answer

What is the value of ΔH for this dissociation reaction?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Assume that the reaction CO(g) + H2O(g) CO2(g) + H2(g) Occurs in an mixture of ideal gases. At 700 K, Kp = 5.10. At this temperature, what is ΔG°?

Correct AnswerverifiedShow Answer

In which case must a reaction be spontaneous at all temperatures?

Correct AnswerverifiedShow Answer

One mole of an ideal gas is compressed isothermally at 607.4 K from 5.60 atm to 8.90 atm. If the process is carried out in two irreversible steps (intermediate step at P = 7.00 atm) , calculate the following.ΔS

Correct AnswerverifiedShow Answer

A gas expands isothermally and irreversibly. -ΔG is

Correct AnswerverifiedShow Answer

The process H2O(g) → H2O(l) takes place at 1 atm and 95°C. -6.00 mol of a monatomic ideal gas is cooled from 254°C to 24°C at constant volume. Calculate ΔS.

Correct AnswerverifiedShow Answer

One mole of an ideal gas expands isothermally and reversibly at 0°C. The pressure on 1 mol of an ideal monatomic gas changes from 100.0 atm to 1.00 atm. -Calculate q.

Correct AnswerverifiedShow Answer

Given that S° = 131 J/Kmol for H2(g) , estimate the value of ΔS° for the reaction

Correct AnswerverifiedShow Answer

The standard free energy of formation of nitric oxide, NO, at 1000. K (roughly the temperature in an automobile engine during ignition) is 78 kJ/mol. Calculate the equilibrium constant for the reaction N2(g) + O2(g) 2NO(g) At 1000. K.

Correct AnswerverifiedShow Answer

At 699 K, ΔG° = -23.25 kJ for the reaction H2(g) + I2(g) 2HI(g) . Calculate ΔG for this reaction if the reagents are both supplied at 10.0 atm pressure and the product is at 1.00 atm pressure.

Correct AnswerverifiedShow Answer

In which reaction is ΔS° expected to be positive?

Correct AnswerverifiedShow Answer

A gas expands isothermally and irreversibly. -ΔS is

Correct AnswerverifiedShow Answer

The standard molar free energies of formation of NO₂(g) and N₂O₄(g) at 25°C are 51.84 and 98.28 kJ/mol, respectively. What is the value of K_p (in atm) for the reaction written as follows at 25°C? 2NO₂ N₂O₄

Correct Answer
verified

Correct Answer
verified

The process H₂O(g) → H₂O(l) takes place at 1 atm and 95°C. -Calculate ΔS for cooling 2.60 mol of an ideal monatomic gas from 88°C to 39°C at constant volume.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Assume that the reaction CO(g) + H₂O(g) CO₂(g) + H₂(g) Occurs in an mixture of ideal gases. At 700 K, K_p = 5.10. At this temperature, what is ΔG°?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

The process H₂O(g) → H₂O(l) takes place at 1 atm and 95°C. -6.00 mol of a monatomic ideal gas is cooled from 254°C to 24°C at constant volume. Calculate ΔS.

Correct Answer
verified

Correct Answer
verified

Given that S° = 131 J/Kmol for H₂(g) , estimate the value of ΔS° for the reaction

Correct Answer
verified

The standard free energy of formation of nitric oxide, NO, at 1000. K (roughly the temperature in an automobile engine during ignition) is 78 kJ/mol. Calculate the equilibrium constant for the reaction N₂(g) + O₂(g) 2NO(g) At 1000. K.

Correct Answer
verified

At 699 K, ΔG° = -23.25 kJ for the reaction H₂(g) + I₂(g) 2HI(g) . Calculate ΔG for this reaction if the reagents are both supplied at 10.0 atm pressure and the product is at 1.00 atm pressure.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified