Question 1

The following reaction is spontaneous at all temperatures:
CaC2(s)+ 2H2O(l)→ Ca(OH)2(s)+ C2H2(g)
Which of the following statements is true?

Accepted Answer

A) ΔH is negative and ΔS is positive. 
B) ΔH is negative and ΔS is negative. 
C) ΔH is positive and ΔS is negative. 
D) ΔH is positive and ΔS is positive. 
E) ΔG is positive at all temperatures. 
A) ΔH is negative and ΔS is positive. 
B) ΔH is negative and ΔS is negative. 
C) ΔH is positive and ΔS is negative. 
D) ΔH is positive and ΔS is positive. 
E) ΔG is positive at all temperatures.

Question 2

Determine ΔG° for the following reaction:
CH4(g)+ 2O2(g)  
CO2(g)+ 2H2O(l)

Accepted Answer

A) -581.2 kJ 
B) -818.6 kJ 
C) 131.1 kJ 
D) -682.5 kJ 
E) -919.9 kJ 
A) -581.2 kJ 
B) -818.6 kJ 
C) 131.1 kJ 
D) -682.5 kJ 
E) -919.9 kJ

Question 3

Consider the following reaction:
2C(s)+ 2H2(g)→ C2H4(g); ΔH° = 52.47 kJ; ΔS° = -53.5 J/K at 298 K
What is the equilibrium constant at 298 K for this reaction?

Accepted Answer

A) 1.0 × 10-12 
B) 1.0 
C) 1.6 × 10-3 
D) 9.8 × 1011 
E) 6.4 × 10-10 
A) 1.0 × 10-12 
B) 1.0 
C) 1.6 × 10-3 
D) 9.8 × 1011 
E) 6.4 × 10-10

Question 4

What is the change in internal energy of the system (ΔU)if 82 kJ of heat energy is absorbed by the system and 40 kJ of work is done on the system for a certain process?

Accepted Answer

A) 122 kJ 
B) 42 kJ 
C) 82 kJ 
D) -122 kJ 
E) -42 kJ 
A) 122 kJ 
B) 42 kJ 
C) 82 kJ 
D) -122 kJ 
E) -42 kJ

Question 5

An ideal fuel for the control jet of a space vehicle should decompose with

Accepted Answer

A) ΔG = 0 and ΔH = 0. B) ΔG 0 and ΔH > 0. D) ΔG 0. E) ΔG > 0 and ΔH < 0. A) ΔG = 0 and ΔH = 0. B) ΔG 0 and ΔH > 0. D) ΔG 0. E) ΔG > 0 and ΔH < 0.

Question 6

For which of the following reactions is ΔS° > 0 at 25°C?

Accepted Answer

A) 2H2(g)+ O2(g)→ 2H2O(g) 
B) 2ClBr(g)→ Cl2(g)+ Br2(g) 
C) I2(g)→ I2(s) 
D) 2NO(g)+ O2(g)→ 2NO2(g) 
E) NH4HS(s)→ NH3(g)+ H2S(g) 
A) 2H2(g)+ O2(g)→ 2H2O(g) 
B) 2ClBr(g)→ Cl2(g)+ Br2(g) 
C) I2(g)→ I2(s) 
D) 2NO(g)+ O2(g)→ 2NO2(g) 
E) NH4HS(s)→ NH3(g)+ H2S(g)

Question 7

Which of the following has the lowest entropy per mole?

Accepted Answer

A) liquid sodium at 100°C 
B) gaseous sodium at 900°C and 0.5 atm 
C) a solid solution of sodium in potassium at 30°C 
D) gaseous sodium at 900°C and 1 atm 
E) solid sodium at 30°C 
A) liquid sodium at 100°C 
B) gaseous sodium at 900°C and 0.5 atm 
C) a solid solution of sodium in potassium at 30°C 
D) gaseous sodium at 900°C and 1 atm 
E) solid sodium at 30°C

Question 8

Given the following,determine K at 298K for the reaction,
AgI(s)→ Ag+(aq)+I−(aq)

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 9

A 0.0333 M solution of a particular weak base,B,has a pH of 8.30 at 298 K.What is ΔG° for the following equilibrium?
B(aq)+ H2O(l)  BH+(aq)+ OH-(aq)

Accepted Answer

A) 32.5 kJ 
B) 47.3 kJ 
C) 8.42 kJ 
D) 56.5 kJ 
E) 86.2 kJ 
A) 32.5 kJ 
B) 47.3 kJ 
C) 8.42 kJ 
D) 56.5 kJ 
E) 86.2 kJ

Question 10

For the reaction N2(g)→ 2N(g),

Accepted Answer

A) ΔH  0 and ΔS  0. 
D) ΔH = 0 and ΔS > 0. 
E) ΔH > 0 and ΔS > 0. 
A) ΔH  0 and ΔS  0. 
D) ΔH = 0 and ΔS > 0. 
E) ΔH > 0 and ΔS > 0.

Question 11

What is the change in entropy when 0.802 g of silicon is burned in excess oxygen to yield silicon dioxide at 298 K?
Si(s)+ O2(g)→ SiO2(s); ΔS° = -182.4 J/K at 298 K

Accepted Answer

A) 182J/K 
B) 146 J/K 
C) -1.75 × 10-2 J/K 
D) -6.39 × 103 J/K 
E) 5.2 J/K 
A) 182J/K 
B) 146 J/K 
C) -1.75 × 10-2 J/K 
D) -6.39 × 103 J/K 
E) 5.2 J/K

Question 12

The free-energy change of a reaction is a measure of

Accepted Answer

A) the excess entropy given off to the reaction system. 
B) the increased molecular disorder that occurs in the system. 
C) the energy given off to the surroundings. 
D) the direction in which a net reaction occurs. 
E) the excess entropy given off to the surroundings. 
A) the excess entropy given off to the reaction system. 
B) the increased molecular disorder that occurs in the system. 
C) the energy given off to the surroundings. 
D) the direction in which a net reaction occurs. 
E) the excess entropy given off to the surroundings.

Question 13

For which of the following reactions is ΔS° at 25°C closest to zero?

Accepted Answer

A) N2(g)+ O2(g)→ 2NO(g) 
B) H2(g)+ I2(s)→ 2HI(g) 
C) CH3CHO(g)+ 5/2O2(g)→ 2CO2(g)+ 2H2O(g) 
D) 2NO(g)+ O2(g)→ 2NO2(g) 
E) C2H4(g)+ Br2(l)→ C2H4Br2(l) 
A) N2(g)+ O2(g)→ 2NO(g) 
B) H2(g)+ I2(s)→ 2HI(g) 
C) CH3CHO(g)+ 5/2O2(g)→ 2CO2(g)+ 2H2O(g) 
D) 2NO(g)+ O2(g)→ 2NO2(g) 
E) C2H4(g)+ Br2(l)→ C2H4Br2(l)

Question 14

What is ΔG° at 500.0 K for the following reaction?
Zn(s)+ H2O(g)→ ZnO(s)+ H2(g)

Accepted Answer

A) 80.7 kJ 
B) -80.7 kJ 
C) 92.0 kJ 
D) -92.0 kJ 
E) -136.7 kJ 
A) 80.7 kJ 
B) -80.7 kJ 
C) 92.0 kJ 
D) -92.0 kJ 
E) -136.7 kJ

Question 15

Consider the following hypothetical reaction at 310 K.Standard free energies of formation are given in parentheses.
B  C ΔG° = -25.0kJ/mol
(?) (176.4 kJ/mol)
Calculate the standard free energy of formation of compound B.

Accepted Answer

A) 151.4 kJ/mol 
B) -201.4 kJ/mol 
C) -151.4kJ/mol 
D) 201.4 kJ/mol 
E) none of these 
A) 151.4 kJ/mol 
B) -201.4 kJ/mol 
C) -151.4kJ/mol 
D) 201.4 kJ/mol 
E) none of these

Question 16

Which of the following is not a state function?

Accepted Answer

A) w 
B) H 
C) P 
D) U 
E) T 
A) w 
B) H 
C) P 
D) U 
E) T

Question 17

For a certain process,at 300.K,ΔG = -37.2 kJ and ΔH = -7.0 kJ.If the process is carried out reversibly,what is the amount of useful work that can be performed?

Accepted Answer

A) -7.0 kJ 
B) -44.2 kJ 
C) -30.2 kJ 
D) 30.2 kJ 
E) -37.2 kJ 
A) -7.0 kJ 
B) -44.2 kJ 
C) -30.2 kJ 
D) 30.2 kJ 
E) -37.2 kJ

Question 18

Consider the following reaction,which is spontaneous at room temperature.
C3H8(g)+ 5O2(g)→ 3CO2(g)+ 4H2O(g)
One would predict that

Accepted Answer

A) ΔH is positive and ΔS is positive for the reaction. 
B) ΔG is positive at all temperatures. 
C) ΔH is negative and ΔS is negative for the reaction. 
D) ΔH is positive and ΔS is negative for the reaction. 
E) ΔH is negative and ΔS is positive for the reaction. 
A) ΔH is positive and ΔS is positive for the reaction. 
B) ΔG is positive at all temperatures. 
C) ΔH is negative and ΔS is negative for the reaction. 
D) ΔH is positive and ΔS is negative for the reaction. 
E) ΔH is negative and ΔS is positive for the reaction.

Question 19

The third law of thermodynamics states that

Accepted Answer

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

Question 20

For the reaction MgSO3(s)→ MgO(s)+ SO2(g),which is spontaneous only at high temperatures,one would predict that

Accepted Answer

A) ΔH is negative and ΔS is negative at room temperature. 
B) ΔH is positive and ΔS is positive at room temperature. 
C) ΔH is positive and ΔS is negative at room temperature. 
D) ΔG is positive at high temperatures. 
E) ΔH is negative and ΔS is positive at room temperature. 
A) ΔH is negative and ΔS is negative at room temperature. 
B) ΔH is positive and ΔS is positive at room temperature. 
C) ΔH is positive and ΔS is negative at room temperature. 
D) ΔG is positive at high temperatures. 
E) ΔH is negative and ΔS is positive at room temperature.

Exam 18: Thermodynamics and Equilibrium

The following reaction is spontaneous at all temperatures: CaC2(s)+ 2H2O(l)→ Ca(OH)2(s)+ C2H2(g) Which of the following statements is true?

Determine ΔG° for the following reaction: CH4(g)+ 2O2(g) CO2(g)+ 2H2O(l)

Consider the following reaction: 2C(s)+ 2H2(g)→ C2H4(g); ΔH° = 52.47 kJ; ΔS° = -53.5 J/K at 298 K What is the equilibrium constant at 298 K for this reaction?

What is the change in internal energy of the system (ΔU)if 82 kJ of heat energy is absorbed by the system and 40 kJ of work is done on the system for a certain process?

An ideal fuel for the control jet of a space vehicle should decompose with

For which of the following reactions is ΔS° > 0 at 25°C?

Which of the following has the lowest entropy per mole?

Given the following,determine K at 298K for the reaction, AgI(s)→ Ag+(aq)+I−(aq)

A 0.0333 M solution of a particular weak base,B,has a pH of 8.30 at 298 K.What is ΔG° for the following equilibrium? B(aq)+ H2O(l) BH+(aq)+ OH-(aq)

For the reaction N2(g)→ 2N(g),

What is the change in entropy when 0.802 g of silicon is burned in excess oxygen to yield silicon dioxide at 298 K? Si(s)+ O2(g)→ SiO2(s); ΔS° = -182.4 J/K at 298 K

The free-energy change of a reaction is a measure of

For which of the following reactions is ΔS° at 25°C closest to zero?

What is ΔG° at 500.0 K for the following reaction? Zn(s)+ H2O(g)→ ZnO(s)+ H2(g)

Consider the following hypothetical reaction at 310 K.Standard free energies of formation are given in parentheses. B C ΔG° = -25.0kJ/mol (?) (176.4 kJ/mol) Calculate the standard free energy of formation of compound B.

Which of the following is not a state function?

For a certain process,at 300.K,ΔG = -37.2 kJ and ΔH = -7.0 kJ.If the process is carried out reversibly,what is the amount of useful work that can be performed?

Consider the following reaction,which is spontaneous at room temperature. C3H8(g)+ 5O2(g)→ 3CO2(g)+ 4H2O(g) One would predict that

The third law of thermodynamics states that

For the reaction MgSO3(s)→ MgO(s)+ SO2(g),which is spontaneous only at high temperatures,one would predict that

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The following reaction is spontaneous at all temperatures: CaC₂(s)+ 2H₂O(l)→ Ca(OH)₂(s)+ C₂H₂(g) Which of the following statements is true?

Determine ΔG° for the following reaction: CH₄(g)+ 2O₂(g) CO₂(g)+ 2H₂O(l)

Consider the following reaction: 2C(s)+ 2H₂(g)→ C₂H₄(g); ΔH° = 52.47 kJ; ΔS° = -53.5 J/K at 298 K What is the equilibrium constant at 298 K for this reaction?

Given the following,determine K at 298K for the reaction, AgI(s)→ Ag⁺(aq)+I−(aq)

A 0.0333 M solution of a particular weak base,B,has a pH of 8.30 at 298 K.What is ΔG° for the following equilibrium? B(aq)+ H₂O(l) BH⁺(aq)+ OH^-(aq)

For the reaction N₂(g)→ 2N(g),

What is the change in entropy when 0.802 g of silicon is burned in excess oxygen to yield silicon dioxide at 298 K? Si(s)+ O₂(g)→ SiO₂(s); ΔS° = -182.4 J/K at 298 K

What is ΔG° at 500.0 K for the following reaction? Zn(s)+ H₂O(g)→ ZnO(s)+ H₂(g)

Consider the following reaction,which is spontaneous at room temperature. C₃H₈(g)+ 5O₂(g)→ 3CO₂(g)+ 4H₂O(g) One would predict that

For the reaction MgSO₃(s)→ MgO(s)+ SO₂(g),which is spontaneous only at high temperatures,one would predict that