Question 1

Which of the following result(s) in an increase in the entropy of the system? 
I. 2(g)  	o  Br2(l)  III. NaBr(s)  	o Na+(aq) + Br-(aq)  IV. O2(298 K)  	o  O2(373 K)  V. NH3(1 atm,298 K)  	o  NH3(3 atm,298 K)  A) I B) II,V C) I,III,IV D) I,II,III,IV E) I,II,III,V " class="answers-bank-image d-inline" rel="preload" > 
II.
Br2(g)  →	o→  Br2(l) 
III.
NaBr(s)  →	o→ Na+(aq) + Br-(aq) 
IV.
O2(298 K)  →	o→  O2(373 K) 
V.
NH3(1 atm,298 K)  →	o→  NH3(3 atm,298 K)

Accepted Answer

A)  I
B)  II,V
C)  I,III,IV
D)  I,II,III,IV
E)  I,II,III,V

Question 2

Which statement is true?

Accepted Answer

A)  All real processes are irreversible.
B)  A thermodynamically reversible process takes place infinitely fast.
C)  In a reversible process,the state functions of the system are always much greater than those of the surroundings.
D)  There is always more heat given off to the surroundings in a reversible process than in an unharnessed one.
E)  All statements (A-
D)  are true.

Question 3

The value of  Δ\DeltaΔ H for this dissociation reaction is:

Accepted Answer

A)  -137.3 kJ
B)  137.3 kJ
C)  1.986 kJ
D)  -1.986 kJ
E)  none of these

Question 4

For the reaction   Δ\DeltaΔ H° = 126.4 kJ/mol and  Δ\DeltaΔ S° = -74.9 J/K mol. At 361°C,what is  Δ\DeltaΔ G ?

Accepted Answer

A)  153.4 kJ/mol
B)  47.6 kJ/mol
C)  173.9 kJ/mol
D)  78.9 kJ/mol
E)  155.0 kJ/mol

Question 5

For the process CHCl3(s)   →	o→ CHCl3(l) , Δ\DeltaΔ H° = 9.19 kJ/mol and  Δ\DeltaΔ S° = 43.9 J/mol/K.What is the melting point of chloroform?

Accepted Answer

A)  -64 °C
B)  209 °C
C)  130 °C
D)  64 °C
E)  -130 °C

Question 6

Substance X has a heat of vaporization of 58.4 kJ/mol at its normal boiling point (423°C) .For the process X(l)  →	o→ X(g) at 1 atm and 423°C calculate the value of  Δ\DeltaΔ Ssurr.

Accepted Answer

A)  0
B)  83.9 J/K mol
C)  138 J/K mol
D)  -83.9 J/K mol
E)  -138 J/K mol

Question 7

For the dissociation reaction of the acid HF: HF(aq)  +(aq) + F-(aq)   \Delta S is observed to be negative.The best explanation is: A) This is the expected result since each HF molecule produces two ions when it dissociates. B) Hydration of the ions produces the negative value of  \Delta S. C) The reaction is expected to be exothermic and thus  \Delta S should be negative. D) The reaction is expected to be endothermic and thus  \Delta S should be negative. E) None of these can explain the negative value of  \Delta S. " class="answers-bank-image d-inline" rel="preload" > H+(aq) + F-(aq) 
 Δ\DeltaΔ S is observed to be negative.The best explanation is:

Accepted Answer

A)  This is the expected result since each HF molecule produces two ions when it dissociates.
B)  Hydration of the ions produces the negative value of  Δ\DeltaΔ S.
C)  The reaction is expected to be exothermic and thus  Δ\DeltaΔ S should be negative.
D)  The reaction is expected to be endothermic and thus  Δ\DeltaΔ S should be negative.
E)  None of these can explain the negative value of  Δ\DeltaΔ S.  B

Question 8

A 100-mL sample of water is placed in a coffee cup calorimeter.When 1.0 g of an ionic solid is added,the temperature decreases from 21.5°C to 20.8°C as the solid dissolves.For the dissolving of the solid

Accepted Answer

A)  ( Δ\DeltaΔ H 
B)  ( Δ\DeltaΔ Suniv > 0) 
C)  ( Δ\DeltaΔ Ssys
D)  ( Δ\DeltaΔ Ssurr > 0) 
E)  none of these  B

Question 9

The third law of thermodynamics states:

Accepted Answer

A)  The entropy of the universe is increasing.
B)  The entropy of the universe is constant.
C)  The entropy is zero at 0 K for a perfect crystal.
D)  The absolute entropy of a substance decreases with increasing temperature.
E)  The entropy of the universe equals the sum of the entropy of system and surroundings.

Question 10

When ignited,solid ammonium dichromate decomposes in a fiery display.This is the reaction for a "volcano" demonstration.The decomposition produces nitrogen gas,water vapor,and chromium(III) oxide.The temperature is constant at 25°C.

-Determine  Δ\DeltaΔ G° (in kJ/mol) .

Accepted Answer

A)  -191.4
B)  -2281.4
C)  -38.9
D)  1903.6
E)  -1555.4

Question 11

$\Delta$H° is zero for a chemical reaction at constant temperature.

Accepted Answer

A) True 
 B)False

Question 12

The acid dissociation constant for a weak acid HX at 25°C is 4.3 -8.Calculate the free energy of formation for X-(aq) at 25°C.The standard free energies of HX(aq) and H+(aq) at 25°C are -208.3 kJ/mol and 0,respectively. A) -205 kJ/mol B) 250 kJ/mol C) 0 D) -166 kJ/mol E) -250 kJ/mol" class="answers-bank-image d-inline" rel="preload" > 10-8.Calculate the free energy of formation for X-(aq) at 25°C.The standard free energies of HX(aq) and H+(aq) at 25°C are -208.3 kJ/mol and 0,respectively.

Accepted Answer

A)  -205 kJ/mol
B)  250 kJ/mol
C)  0
D)  -166 kJ/mol
E)  -250 kJ/mol

Question 13

If the change in entropy of the surroundings for a process at 431 K and constant pressure is -326 J/K,what is the heat flow absorbed by for the system?

Accepted Answer

A)  326 kJ
B)  1.32 kJ
C)  -141 kJ
D)  105 kJ
E)  141 kJ

Question 14

For the following reaction,CO2(g) + 2H2O(g)  2(g) + 2H2O(g)    CH4(g) + 2O2(g) , \Delta H° = 803 kJ which of the following will increase K? A) decrease number of moles of methane B) increase volume of system C) increase the temperature of system D) all of the above E) none of the above " class="answers-bank-image d-inline" rel="preload" > CH4(g) + 2O2(g) , Δ\DeltaΔ H° = 803 kJ which of the following will increase K?

Accepted Answer

A)  decrease number of moles of methane
B)  increase volume of system
C)  increase the temperature of system
D)  all of the above
E)  none of the above

Question 15

Given that  Δ\DeltaΔ Hvap is 53.3 kJ/mol,and the boiling point is 83.4°C,1 atm,if one mole of this substance is vaporized at 1 atm,calculate  Δ\DeltaΔ G.

Accepted Answer

A)  -150 J
B)  150 J
C)  639 J
D)  -639 J
E)  0 J

Question 16

Consider the following system at equilibrium at 25°C:
PCl3(g) + Cl2(g)  3(g) + Cl2(g)    PCl5(g)  for which  \Delta H° = -92.5kJ at 25°C. -When the volume is decreased at constant temperature,the ratio of the partial pressure of PCl5 to the partial pressure of PCl3 will A) increase B) decrease C) stay the same D) impossible to tell without more information E) none of these " class="answers-bank-image d-inline" rel="preload" > PCl5(g) 
for which  Δ\DeltaΔ H° = -92.5kJ at 25°C.
-When the volume is decreased at constant temperature,the ratio of the partial pressure of PCl5 to the partial pressure of PCl3 will

Accepted Answer

A)  increase
B)  decrease
C)  stay the same
D)  impossible to tell without more information
E)  none of these

Question 17

Assume that the enthalpy of fusion of ice is 6020 J/mol and does not vary appreciably over the temperature range 270-290 K.If one mole of ice at 0°C is melted by heat supplied from surroundings at 276 K,what is the entropy change in the surroundings,in J/K?

Accepted Answer

A)  22.1
B)  21.8
C)  0.0
D)  -21.8
E)  -22.1

Question 18

Substance X has a heat of vaporization of 64.4 kJ/mol at its normal boiling point (423°C) .For the process X(l)  →	o→  X(g) at 1 atm and 423°C calculate the value of  Δ\DeltaΔ G.

Accepted Answer

A)  0 J
B)  92.5 J
C)  152 J
D)  -92.5 J
E)  -152 J  A

Question 19

For a certain process at 355 K, Δ\DeltaΔ G = -11.8 kJ and  Δ\DeltaΔ H = -9.2 kJ.Therefore, Δ\DeltaΔ S for the process is

Accepted Answer

A)  0 J/K mol
B)  7.3 J/K mol
C)  -7.3 J/K mol
D)  -25.9 J/K mol
E)  25.9 J/K mol

Question 20

Consider the following system at equilibrium at 25°C:
PCl3(g) + Cl2(g)  3(g) + Cl2(g)    PCl5(g)  for which  \Delta H° = -92.5kJ at 25°C. -When some Cl2(g) is added at constant volume and temperature,the ratio of the partial pressure of PCl5 to the partial pressure of PCl3 will A) increase B) decrease C) stay the same D) impossible to tell without more information E) none of these " class="answers-bank-image d-inline" rel="preload" > PCl5(g) 
for which  Δ\DeltaΔ H° = -92.5kJ at 25°C.
-When some Cl2(g) is added at constant volume and temperature,the ratio of the partial pressure of PCl5 to the partial pressure of PCl3 will

Accepted Answer

A)  increase
B)  decrease
C)  stay the same
D)  impossible to tell without more information
E)  none of these

Exam 17: Spontaneity, entropy, and Free Energy

Correct Answer
verified

Which statement is true?

Correct Answer
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The value of $\Delta$ H for this dissociation reaction is:

Correct Answer
verified

For the reaction $For the reaction \Delta H° = 126.4 kJ/mol and \Delta S° = -74.9 J/K mol. At 361°C,what is \Delta G ? A) 153.4 kJ/mol B) 47.6 kJ/mol C) 173.9 kJ/mol D) 78.9 kJ/mol E) 155.0 kJ/mol$ $\Delta$ H° = 126.4 kJ/mol and $\Delta$ S° = -74.9 J/K mol. At 361°C,what is $\Delta$ G ?

Correct Answer
verified

For the process CHCl₃(s) $\to$ CHCl₃(l) , $\Delta$ H° = 9.19 kJ/mol and $\Delta$ S° = 43.9 J/mol/K.What is the melting point of chloroform?

Correct Answer
verified

Substance X has a heat of vaporization of 58.4 kJ/mol at its normal boiling point (423°C) .For the process X(l) $\to$ X(g) at 1 atm and 423°C calculate the value of $\Delta$ S_surr.

Correct Answer
verified

Correct Answer
verified
B

A 100-mL sample of water is placed in a coffee cup calorimeter.When 1.0 g of an ionic solid is added,the temperature decreases from 21.5°C to 20.8°C as the solid dissolves.For the dissolving of the solid

Correct Answer
verified
B

The third law of thermodynamics states:

Correct Answer
verified

Correct Answer
verified

$\Delta$ H° is zero for a chemical reaction at constant temperature.

Correct Answer
verified

The acid dissociation constant for a weak acid HX at 25°C is 4.3 10^-⁸.Calculate the free energy of formation for X^-(aq) at 25°C.The standard free energies of HX(aq) and H⁺(aq) at 25°C are -208.3 kJ/mol and 0,respectively.

Correct Answer
verified

If the change in entropy of the surroundings for a process at 431 K and constant pressure is -326 J/K,what is the heat flow absorbed by for the system?

Correct Answer
verified

Correct Answer
verified

Given that $\Delta$ H_vap is 53.3 kJ/mol,and the boiling point is 83.4°C,1 atm,if one mole of this substance is vaporized at 1 atm,calculate $\Delta$ G.

Correct Answer
verified

Correct Answer
verified

Assume that the enthalpy of fusion of ice is 6020 J/mol and does not vary appreciably over the temperature range 270-290 K.If one mole of ice at 0°C is melted by heat supplied from surroundings at 276 K,what is the entropy change in the surroundings,in J/K?

Correct Answer
verified

Substance X has a heat of vaporization of 64.4 kJ/mol at its normal boiling point (423°C) .For the process X(l) $\to$ X(g) at 1 atm and 423°C calculate the value of $\Delta$ G.

Correct Answer
verified
A

For a certain process at 355 K, $\Delta$ G = -11.8 kJ and $\Delta$ H = -9.2 kJ.Therefore, $\Delta$ S for the process is

Correct Answer
verified

Correct Answer
verified

Exam 17: Spontaneity, entropy, and Free Energy

Which of the following result(s) in an increase in the entropy of the system? I. II. Br2(g) →\to→ Br2(l) III. NaBr(s) →\to→ Na+(aq) + Br-(aq) IV. O2(298 K) →\to→ O2(373 K) V. NH3(1 atm,298 K) →\to→ NH3(3 atm,298 K)

Correct AnswerverifiedShow Answer

Which statement is true?

Correct AnswerverifiedShow Answer

The value of Δ\DeltaΔ H for this dissociation reaction is:

Correct AnswerverifiedShow Answer

For the reaction Δ\DeltaΔ H° = 126.4 kJ/mol and Δ\DeltaΔ S° = -74.9 J/K mol. At 361°C,what is Δ\DeltaΔ G ?

Correct AnswerverifiedShow Answer

For the process CHCl3(s) →\to→ CHCl3(l) , Δ\DeltaΔ H° = 9.19 kJ/mol and Δ\DeltaΔ S° = 43.9 J/mol/K.What is the melting point of chloroform?

Correct AnswerverifiedShow Answer

Substance X has a heat of vaporization of 58.4 kJ/mol at its normal boiling point (423°C) .For the process X(l) →\to→ X(g) at 1 atm and 423°C calculate the value of Δ\DeltaΔ Ssurr.

Correct AnswerverifiedShow Answer

For the dissociation reaction of the acid HF: HF(aq) H+(aq) + F-(aq) Δ\DeltaΔ S is observed to be negative.The best explanation is:

Correct AnswerverifiedB

A 100-mL sample of water is placed in a coffee cup calorimeter.When 1.0 g of an ionic solid is added,the temperature decreases from 21.5°C to 20.8°C as the solid dissolves.For the dissolving of the solid

Correct AnswerverifiedB

The third law of thermodynamics states:

Correct AnswerverifiedShow Answer

When ignited,solid ammonium dichromate decomposes in a fiery display.This is the reaction for a "volcano" demonstration.The decomposition produces nitrogen gas,water vapor,and chromium(III) oxide.The temperature is constant at 25°C. -Determine Δ\DeltaΔ G° (in kJ/mol) .

Correct AnswerverifiedShow Answer

Δ\DeltaΔ H° is zero for a chemical reaction at constant temperature.

Correct AnswerverifiedShow Answer

The acid dissociation constant for a weak acid HX at 25°C is 4.3 10-8.Calculate the free energy of formation for X-(aq) at 25°C.The standard free energies of HX(aq) and H+(aq) at 25°C are -208.3 kJ/mol and 0,respectively.

Correct AnswerverifiedShow Answer

If the change in entropy of the surroundings for a process at 431 K and constant pressure is -326 J/K,what is the heat flow absorbed by for the system?

Correct AnswerverifiedShow Answer

For the following reaction,CO2(g) + 2H2O(g) CH4(g) + 2O2(g) , Δ\DeltaΔ H° = 803 kJ which of the following will increase K?

Correct AnswerverifiedShow Answer

Given that Δ\DeltaΔ Hvap is 53.3 kJ/mol,and the boiling point is 83.4°C,1 atm,if one mole of this substance is vaporized at 1 atm,calculate Δ\DeltaΔ G.

Correct AnswerverifiedShow Answer

Consider the following system at equilibrium at 25°C: PCl3(g) + Cl2(g) PCl5(g) for which Δ\DeltaΔ H° = -92.5kJ at 25°C. -When the volume is decreased at constant temperature,the ratio of the partial pressure of PCl5 to the partial pressure of PCl3 will

Correct AnswerverifiedShow Answer

Assume that the enthalpy of fusion of ice is 6020 J/mol and does not vary appreciably over the temperature range 270-290 K.If one mole of ice at 0°C is melted by heat supplied from surroundings at 276 K,what is the entropy change in the surroundings,in J/K?

Correct AnswerverifiedShow Answer

Substance X has a heat of vaporization of 64.4 kJ/mol at its normal boiling point (423°C) .For the process X(l) →\to→ X(g) at 1 atm and 423°C calculate the value of Δ\DeltaΔ G.

Correct AnswerverifiedA

For a certain process at 355 K, Δ\DeltaΔ G = -11.8 kJ and Δ\DeltaΔ H = -9.2 kJ.Therefore, Δ\DeltaΔ S for the process is

Correct AnswerverifiedShow Answer

Consider the following system at equilibrium at 25°C: PCl3(g) + Cl2(g) PCl5(g) for which Δ\DeltaΔ H° = -92.5kJ at 25°C. -When some Cl2(g) is added at constant volume and temperature,the ratio of the partial pressure of PCl5 to the partial pressure of PCl3 will

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

The value of $\Delta$ H for this dissociation reaction is:

Correct Answer
verified

For the reaction $For the reaction \Delta H° = 126.4 kJ/mol and \Delta S° = -74.9 J/K mol. At 361°C,what is \Delta G ? A) 153.4 kJ/mol B) 47.6 kJ/mol C) 173.9 kJ/mol D) 78.9 kJ/mol E) 155.0 kJ/mol$ $\Delta$ H° = 126.4 kJ/mol and $\Delta$ S° = -74.9 J/K mol. At 361°C,what is $\Delta$ G ?

Correct Answer
verified

For the process CHCl₃(s) $\to$ CHCl₃(l) , $\Delta$ H° = 9.19 kJ/mol and $\Delta$ S° = 43.9 J/mol/K.What is the melting point of chloroform?

Correct Answer
verified

Substance X has a heat of vaporization of 58.4 kJ/mol at its normal boiling point (423°C) .For the process X(l) $\to$ X(g) at 1 atm and 423°C calculate the value of $\Delta$ S_surr.

Correct Answer
verified

Correct Answer
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B

Correct Answer
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B

Correct Answer
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Correct Answer
verified

$\Delta$ H° is zero for a chemical reaction at constant temperature.

Correct Answer
verified

The acid dissociation constant for a weak acid HX at 25°C is 4.3 10^-⁸.Calculate the free energy of formation for X^-(aq) at 25°C.The standard free energies of HX(aq) and H⁺(aq) at 25°C are -208.3 kJ/mol and 0,respectively.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Given that $\Delta$ H_vap is 53.3 kJ/mol,and the boiling point is 83.4°C,1 atm,if one mole of this substance is vaporized at 1 atm,calculate $\Delta$ G.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Substance X has a heat of vaporization of 64.4 kJ/mol at its normal boiling point (423°C) .For the process X(l) $\to$ X(g) at 1 atm and 423°C calculate the value of $\Delta$ G.

Correct Answer
verified
A

For a certain process at 355 K, $\Delta$ G = -11.8 kJ and $\Delta$ H = -9.2 kJ.Therefore, $\Delta$ S for the process is

Correct Answer
verified

Correct Answer
verified