Question 1

Entropy is a measure of

Accepted Answer

A) free energy. 
B) the heat of a reaction. 
C) molecular randomness. 
D) the rate of a reaction. 
A) free energy. 
B) the heat of a reaction. 
C) molecular randomness. 
D) the rate of a reaction.

Question 2

Consider the reaction:
N2(g)+ 3 F2(g)→ 2 NF3(g)ΔH° = -249 kJ and ΔS° = -278 J/K at 25°C
Calculate ΔG° and state whether the equilibrium composition should favor reactants or products at standard conditions.

Accepted Answer

A) ΔG° = -332 kJ;the equilibrium composition should favor products. 
B) ΔG° = -332 kJ;the equilibrium composition should favor reactants. 
C) ΔG° = -166 kJ;the equilibrium composition should favor products. 
D) ΔG° = -166 kJ;the equilibrium composition should favor reactants. 
A) ΔG° = -332 kJ;the equilibrium composition should favor products. 
B) ΔG° = -332 kJ;the equilibrium composition should favor reactants. 
C) ΔG° = -166 kJ;the equilibrium composition should favor products. 
D) ΔG° = -166 kJ;the equilibrium composition should favor reactants.

Question 3

Consider the following gas-phase reaction of AS1U1B12S1U1B0 (shaded spheres)and BS1U1B12S1U1B0 (unshaded spheres):
AS1U1B12S1U1B0(g)+ BS1U1B12S1U1B0(g)⇌ 2 AB(g)ΔG ° = +25 kJ  
-Which of the above reaction mixtures has the most spontaneous forward reaction?

Accepted Answer

A) (1) 
B) (2) 
C) (3) 
D) (4) 
A) (1) 
B) (2) 
C) (3) 
D) (4)

Question 4

Calculate the standard free energy for the reaction given.
2 CH3OH(l)+ 3 O2(g)→ 2 CO2(g)+ 4 H2O(l)

Accepted Answer

A) -465.2 kJ 
B) -797.8 kJ 
C) -1404.8 kJ 
D) -2069.8 kJ 
A) -465.2 kJ 
B) -797.8 kJ 
C) -1404.8 kJ 
D) -2069.8 kJ

Question 5

Consider the following gas-phase reaction of AS1U1B12S1U1B0 (shaded spheres)and BS1U1B12S1U1B0 (unshaded spheres):
AS1U1B12S1U1B0(g)+ BS1U1B12S1U1B0(g)⇌ 2 AB(g)ΔG ° = +25 kJ  
-Which of the above reaction mixtures has the least spontaneous forward reaction?

Accepted Answer

A) (1) 
B) (2) 
C) (3) 
D) (4) 
A) (1) 
B) (2) 
C) (3) 
D) (4)

Question 6

Sodium reacts violently with water according to the equation:
2 Na(s)+ 2 H2O(l)→ 2 NaOH(aq)+ H2(g)
The resulting solution has a higher temperature than the water prior to the addition of sodium.What are the signs of ΔH° and ΔS° for this reaction?

Accepted Answer

A) ΔH° is negative and ΔS° is negative. 
B) ΔH° is negative and ΔS° is positive. 
C) ΔH° is positive and ΔS° is negative. 
D) ΔH° is positive and ΔS° is positive. 
A) ΔH° is negative and ΔS° is negative. 
B) ΔH° is negative and ΔS° is positive. 
C) ΔH° is positive and ΔS° is negative. 
D) ΔH° is positive and ΔS° is positive.

Question 7

For the reaction N2(g)+O2(g)→ 2 NO(g),ΔH° = 180.4 kJ/mol and ΔS° = 24.9 J/K.ΔStotal for this reaction is ________ J/K,and the reaction is ________ (spontaneous,nonspontaneous)at 25°C

Accepted Answer

Question 8

The entropy change associated with the expansion of one mole of an ideal gas from an initial volume of Vi to a final volume of Vf at constant temperature is given by the equation,ΔS = R ln (Vf/Vi).What is the entropy change associated with the expansion of three moles of an ideal gas from an initial volume of Vi to a final volume of Vf at constant temperature?

Accepted Answer

A) ΔS = R ln (Vf/Vi) 
B) ΔS = 3 mol × R ln (Vf/Vi) 
C) ΔS = R ln (Vf × 23/Vi) 
D) ΔS = R ln (Vf × 3!/Vi) 
A) ΔS = R ln (Vf/Vi) 
B) ΔS = 3 mol × R ln (Vf/Vi) 
C) ΔS = R ln (Vf × 23/Vi) 
D) ΔS = R ln (Vf × 3!/Vi)

Question 9

The signs of ΔG,ΔH,and ΔS at 25°C are shown below for three reactions.  
Which reaction could go in the reverse direction at high temperature?

Accepted Answer

A) I 
B) II 
C) III 
D) I and II 
A) I 
B) II 
C) III 
D) I and II

Question 10

What is the entropy change associated with the expansion of one mole of an ideal gas from an initial volume of V to a final volume of V of 2.50V at constant temperature?

Accepted Answer

A) ΔS = 2.50 R ln (Vf/Vi) 
B) ΔS = -2.50 R ln (Vf/Vi) 
C) ΔS = R ln 2.50 
D) ΔS = -R ln 2.50 
A) ΔS = 2.50 R ln (Vf/Vi) 
B) ΔS = -2.50 R ln (Vf/Vi) 
C) ΔS = R ln 2.50 
D) ΔS = -R ln 2.50

Question 11

Which electron on an atom of copper would have the highest value of W in the Boltzmann formula?

Accepted Answer

A) 3s 
B) 3d 
C) 4s 
D) 4p 
A) 3s 
B) 3d 
C) 4s 
D) 4p

Question 12

-According to the diagram above,the forward reaction is

Accepted Answer

A) nonspontaneous at d and e,and spontaneous at f. 
B) nonspontaneous at d,at equilibrium at e,and spontaneous at f. 
C) spontaneous at d,at equilibrium at e,and nonspontaneous at f. 
D) spontaneous at d,e,and f. 
A) nonspontaneous at d and e,and spontaneous at f. 
B) nonspontaneous at d,at equilibrium at e,and spontaneous at f. 
C) spontaneous at d,at equilibrium at e,and nonspontaneous at f. 
D) spontaneous at d,e,and f.

Question 13

The brown color associated with photochemical smog is due to NO2(g),which is involved in an equilibrium with N2O4(g)in the atmosphere.
2 NO2(g)⇌ N2O4(g)
Predict the signs of the enthalpy and entropy change for the forward reaction.

Accepted Answer

A) The enthalpy change is negative and the entropy change is negative. 
B) The enthalpy change is negative and the entropy change is positive. 
C) The enthalpy change is positive and the entropy change is negative. 
D) The enthalpy change is positive and the entropy change is positive. 
A) The enthalpy change is negative and the entropy change is negative. 
B) The enthalpy change is negative and the entropy change is positive. 
C) The enthalpy change is positive and the entropy change is negative. 
D) The enthalpy change is positive and the entropy change is positive.

Question 14

At constant pressure and temperature,which statement is true?

Accepted Answer

A) All reactions for which ΔH < 0 are spontaneous. 
B) All reactions for which ΔS < 0 are spontaneous. 
C) All reactions for which ΔG < 0 are spontaneous. 
D) All reactions for which K < 1 are spontaneous. 
A) All reactions for which ΔH < 0 are spontaneous. 
B) All reactions for which ΔS < 0 are spontaneous. 
C) All reactions for which ΔG < 0 are spontaneous. 
D) All reactions for which K < 1 are spontaneous.

Question 15

What is the relationship between ΔG and the ΔG°F for the reaction below?
MgF2(s)→ Mg2+(aq)+ 2 F-(aq)

Accepted Answer

A) ΔG = {ΔG°f [Mg2+ (aq)] + 2 ΔG°f [F- (aq)] - ΔG°f [MgF2 (s)]} + RT ln ([Mg2+] [F-]2/[MgF2]) 
B) ΔG = {ΔG°f [Mg2+ (aq)] + 2 ΔG°f [F- (aq)] - ΔG°f [MgF2 (s)]} + RT ln ([Mg2+] [F-])2) 
C) ΔG = {ΔG°f [Mg2+ (aq)] + 2 ΔG°f [F- (aq)]} + RT ln ([Mg2+] [F-]2) 
D) ΔG = {ΔG°f [Mg2+ (aq)] + 2 ΔG°f [F- (aq)] - ΔG°f [MgF2 (s)]} + RT ln Ksp 
A) ΔG = {ΔG°f [Mg2+ (aq)] + 2 ΔG°f [F- (aq)] - ΔG°f [MgF2 (s)]} + RT ln ([Mg2+] [F-]2/[MgF2]) 
B) ΔG = {ΔG°f [Mg2+ (aq)] + 2 ΔG°f [F- (aq)] - ΔG°f [MgF2 (s)]} + RT ln ([Mg2+] [F-])2) 
C) ΔG = {ΔG°f [Mg2+ (aq)] + 2 ΔG°f [F- (aq)]} + RT ln ([Mg2+] [F-]2) 
D) ΔG = {ΔG°f [Mg2+ (aq)] + 2 ΔG°f [F- (aq)] - ΔG°f [MgF2 (s)]} + RT ln Ksp

Question 16

For the process
CaCO3(calcite)→ CaCO3(aragonite)ΔH° = -0.21 kJ,ΔS° = -4.2 J/K
Assuming that the surroundings can be considered a large heat reservoir at 25°C,calculate ΔSsurr and ΔStotal for the process at 25°C and 1 atm pressure.Is the process spontaneous at 25°C and 1 atm pressure?

Accepted Answer

A) ΔSsurr = 4.2 J/K,Δtotal = 0,not spontaneous 
B) ΔSsurr = 0.7 J/K,ΔStotal = -3.5 J/K,not spontaneous 
C) ΔSsurr = -0.7 J/K,ΔStotal = -4.9 J/K,spontaneous 
D) ΔSsurr = -0.7 J/K,ΔStotal = -4.9 J/K,not spontaneous 
A) ΔSsurr = 4.2 J/K,Δtotal = 0,not spontaneous 
B) ΔSsurr = 0.7 J/K,ΔStotal = -3.5 J/K,not spontaneous 
C) ΔSsurr = -0.7 J/K,ΔStotal = -4.9 J/K,spontaneous 
D) ΔSsurr = -0.7 J/K,ΔStotal = -4.9 J/K,not spontaneous

Question 17

Under which of the following conditions would one mole of Ne have the highest entropy,S?

Accepted Answer

A) 27°C and 25 L 
B) 137°C and 25 L 
C) 27°C and 35 L 
D) 137°C and 35 L 
A) 27°C and 25 L 
B) 137°C and 25 L 
C) 27°C and 35 L 
D) 137°C and 35 L

Question 18

For a reaction at constant temperature,as Q increases

Accepted Answer

A) ΔG and ΔG° increase. 
B) ΔG and ΔG° decrease. 
C) ΔG increases,but ΔG° remains constant. 
D) ΔG decreases,but ΔG° remains constant. 
A) ΔG and ΔG° increase. 
B) ΔG and ΔG° decrease. 
C) ΔG increases,but ΔG° remains constant. 
D) ΔG decreases,but ΔG° remains constant.

Question 19

For the vaporization of solid rhombic sulfur,S(s,rhombic)⇌ S(g),ΔG° = 236.7 kJ/mol.At 25 °C the vapor pressure of rhombic sulfur is ________ atm.

Accepted Answer

The answer of For the vaporization of solid rhombic sulfur,S(s,rhombic)⇌...

Question 20

The solubility of manganese(II)fluoride in water is 6.6 g/mL at 40°C and 4.8 g/L at 100°C.Based on these data,what is the sign of ΔH° and ΔS° for the process below?
MnF2(s)⇌ Mn2+(aq)+ 2 F-(aq)

Accepted Answer

A) ΔH° is negative but the sign of ΔS° cannot be determined from this information. 
B) ΔH° is negative and ΔS° is definitely negative. 
C) ΔH° is positive but the sign of ΔS° cannot be determined from this information. 
D) ΔH° is positive and ΔS° is definitely negative. 
A) ΔH° is negative but the sign of ΔS° cannot be determined from this information. 
B) ΔH° is negative and ΔS° is definitely negative. 
C) ΔH° is positive but the sign of ΔS° cannot be determined from this information. 
D) ΔH° is positive and ΔS° is definitely negative.

Exam 16: Thermodynamics: Entropy, free Energy, and Equilibrium

Entropy is a measure of

Consider the reaction: N2(g)+ 3 F2(g)→ 2 NF3(g)ΔH° = -249 kJ and ΔS° = -278 J/K at 25°C Calculate ΔG° and state whether the equilibrium composition should favor reactants or products at standard conditions.

Consider the following gas-phase reaction of A2 (shaded spheres)and B2 (unshaded spheres): A2(g)+ B2(g)⇌ 2 AB(g)ΔG ° = +25 kJ -Which of the above reaction mixtures has the most spontaneous forward reaction?

Calculate the standard free energy for the reaction given. 2 CH3OH(l)+ 3 O2(g)→ 2 CO2(g)+ 4 H2O(l)

Consider the following gas-phase reaction of A2 (shaded spheres)and B2 (unshaded spheres): A2(g)+ B2(g)⇌ 2 AB(g)ΔG ° = +25 kJ -Which of the above reaction mixtures has the least spontaneous forward reaction?

Sodium reacts violently with water according to the equation: 2 Na(s)+ 2 H2O(l)→ 2 NaOH(aq)+ H2(g) The resulting solution has a higher temperature than the water prior to the addition of sodium.What are the signs of ΔH° and ΔS° for this reaction?

For the reaction N2(g)+O2(g)→ 2 NO(g),ΔH° = 180.4 kJ/mol and ΔS° = 24.9 J/K.ΔStotal for this reaction is ________ J/K,and the reaction is ________ (spontaneous,nonspontaneous)at 25°C

The signs of ΔG,ΔH,and ΔS at 25°C are shown below for three reactions. Which reaction could go in the reverse direction at high temperature?

What is the entropy change associated with the expansion of one mole of an ideal gas from an initial volume of V to a final volume of V of 2.50V at constant temperature?

Which electron on an atom of copper would have the highest value of W in the Boltzmann formula?

-According to the diagram above,the forward reaction is

The brown color associated with photochemical smog is due to NO2(g),which is involved in an equilibrium with N2O4(g)in the atmosphere. 2 NO2(g)⇌ N2O4(g) Predict the signs of the enthalpy and entropy change for the forward reaction.

At constant pressure and temperature,which statement is true?

What is the relationship between ΔG and the ΔG°F for the reaction below? MgF2(s)→ Mg2+(aq)+ 2 F-(aq)

For the process CaCO3(calcite)→ CaCO3(aragonite)ΔH° = -0.21 kJ,ΔS° = -4.2 J/K Assuming that the surroundings can be considered a large heat reservoir at 25°C,calculate ΔSsurr and ΔStotal for the process at 25°C and 1 atm pressure.Is the process spontaneous at 25°C and 1 atm pressure?

Under which of the following conditions would one mole of Ne have the highest entropy,S?

For a reaction at constant temperature,as Q increases

For the vaporization of solid rhombic sulfur,S(s,rhombic)⇌ S(g),ΔG° = 236.7 kJ/mol.At 25 °C the vapor pressure of rhombic sulfur is ________ atm.

The solubility of manganese(II)fluoride in water is 6.6 g/mL at 40°C and 4.8 g/L at 100°C.Based on these data,what is the sign of ΔH° and ΔS° for the process below? MnF2(s)⇌ Mn2+(aq)+ 2 F-(aq)

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Consider the reaction: N₂(g)+ 3 F₂(g)→ 2 NF₃(g)ΔH° = -249 kJ and ΔS° = -278 J/K at 25°C Calculate ΔG° and state whether the equilibrium composition should favor reactants or products at standard conditions.

Consider the following gas-phase reaction of A₂ (shaded spheres)and B₂ (unshaded spheres): A₂(g)+ B₂(g)⇌ 2 AB(g)ΔG ° = +25 kJ -Which of the above reaction mixtures has the most spontaneous forward reaction?

Calculate the standard free energy for the reaction given. 2 CH₃OH(l)+ 3 O₂(g)→ 2 CO₂(g)+ 4 H₂O(l)

Consider the following gas-phase reaction of A₂ (shaded spheres)and B₂ (unshaded spheres): A₂(g)+ B₂(g)⇌ 2 AB(g)ΔG ° = +25 kJ -Which of the above reaction mixtures has the least spontaneous forward reaction?

Sodium reacts violently with water according to the equation: 2 Na(s)+ 2 H₂O(l)→ 2 NaOH(aq)+ H₂(g) The resulting solution has a higher temperature than the water prior to the addition of sodium.What are the signs of ΔH° and ΔS° for this reaction?

For the reaction N₂(g)+O₂(g)→ 2 NO(g),ΔH° = 180.4 kJ/mol and ΔS° = 24.9 J/K.ΔS_total for this reaction is J/K,and the reaction is (spontaneous,nonspontaneous)at 25°C

The brown color associated with photochemical smog is due to NO₂(g),which is involved in an equilibrium with N₂O₄(g)in the atmosphere. 2 NO₂(g)⇌ N₂O₄(g) Predict the signs of the enthalpy and entropy change for the forward reaction.

What is the relationship between ΔG and the ΔG°_F for the reaction below? MgF₂(s)→ Mg²⁺(aq)+ 2 F^-(aq)

The solubility of manganese(II)fluoride in water is 6.6 g/mL at 40°C and 4.8 g/L at 100°C.Based on these data,what is the sign of ΔH° and ΔS° for the process below? MnF₂(s)⇌ Mn²⁺(aq)+ 2 F^-(aq)