Question 1

Calculate ΔS° for the following reaction. N2(g)+ 2 O2(g)→ 2 NO2(g)

Accepted Answer

A) -156.5 J/K 
B) -121.5 J/K 
C) 15.5 J/K 
D) 636.5 J/K 
A) -156.5 J/K 
B) -121.5 J/K 
C) 15.5 J/K 
D) 636.5 J/K

Question 2

What is W in Boltzmann's formula,S = k ln W?

Accepted Answer

A) a fraction indicating the probability of obtaining a result 
B) a random number 
C) the number of ways of obtaining the state 
D) the work times Avogadro's number 
A) a fraction indicating the probability of obtaining a result 
B) a random number 
C) the number of ways of obtaining the state 
D) the work times Avogadro's number

Question 3

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 4

Predict the sign of ΔS for each of the following systems,which occur at constant temperature. I.The volume of 2.0 moles of Ne (g)increases from 54 L to 62 L.
II.The pressure of 2.0 moles of Ne (g)increases from 0.90 atm to 1.0 atm.

Accepted Answer

A) I: ΔS = negative;II: ΔS = negative 
B) I: ΔS = negative;II: ΔS = positive 
C) I: ΔS = positive;II: ΔS = negative 
D) I: ΔS = positive;II: ΔS = positive 
A) I: ΔS = negative;II: ΔS = negative 
B) I: ΔS = negative;II: ΔS = positive 
C) I: ΔS = positive;II: ΔS = negative 
D) I: ΔS = positive;II: ΔS = positive

Question 5

Why is the sign of ΔG rather than the sign of ΔStotal generally used to determine the spontaneity of a chemical reaction?

Accepted Answer

A) ΔG can be used for processes that occur under any conditions. 
B) ΔG involves thermodynamic functions of the system only. 
C) Free energy is easier to understand than entropy. 
D) Entropy is based on probability and is therefore less reliable. 
A) ΔG can be used for processes that occur under any conditions. 
B) ΔG involves thermodynamic functions of the system only. 
C) Free energy is easier to understand than entropy. 
D) Entropy is based on probability and is therefore less reliable.

Question 6

If ΔG° is positive for a reaction,

Accepted Answer

A) K  1. 
A) K  1.

Question 7

ΔS° = -198.7 J/K for the reaction shown below.Calculate S° for NH3(g). N2(g)+ 3 H2(g)→ 2 NH3(g)

Accepted Answer

A) 61.7 J/K∙mol 
B) 123.4 J/K∙mol 
C) 192.3 J/K∙mol 
D) 384.6 J/K∙mol 
A) 61.7 J/K∙mol 
B) 123.4 J/K∙mol 
C) 192.3 J/K∙mol 
D) 384.6 J/K∙mol

Question 8

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 9

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 10

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 11

An electron in an oxygen p orbital on which of the following would have the highest entropy?

Accepted Answer

A) CH3CH2OH 
B) CH3CH2O- 
C) CH3CO2OH 
D) CH3CO2- 
A) CH3CH2OH 
B) CH3CH2O- 
C) CH3CO2OH 
D) CH3CO2-

Question 12

-The figure above represents the reaction O2(g)→ 2O(g),which is nonspontaneous at 25°C.How will the spontaneity of this reaction vary with temperature? This reaction is

Accepted Answer

A) nonspontaneous at all temperatures. 
B) nonspontaneous at high temperatures and spontaneous at low temperatures. 
C) spontaneous at high temperatures and nonspontaneous at low temperatures. 
D) spontaneous at all temperatures. 
A) nonspontaneous at all temperatures. 
B) nonspontaneous at high temperatures and spontaneous at low temperatures. 
C) spontaneous at high temperatures and nonspontaneous at low temperatures. 
D) spontaneous at all temperatures.

Question 13

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

Accepted Answer

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

Question 14

What is k in Boltzmann's formula,S = k ln W?

Accepted Answer

A) the degeneracy of the state 
B) the equilibrium constant for the process 
C) the universal gas constant divided by Avogadro's number 
D) the universal gas constant times Avogadro's number 
A) the degeneracy of the state 
B) the equilibrium constant for the process 
C) the universal gas constant divided by Avogadro's number 
D) the universal gas constant times Avogadro's number

Question 15

At high temperatures,boron carbide vaporizes according to B4C(s)⇌ 4 B(g)+ C(s)
At 2500 K,the equilibrium pressure of B(g)is 0.0342 mm Hg over a mixture of 0.300 mol B4C(s)and 0.500 mol C(s).Calculate ΔG° for this process.

Accepted Answer

A) 832 kJ 
B) 799 kJ 
C) 281 kJ 
D) 247 kJ 
A) 832 kJ 
B) 799 kJ 
C) 281 kJ 
D) 247 kJ

Question 16

Which of the following processes is spontaneous?

Accepted Answer

A) a mixture of two liquids separating into pure compounds 
B) reaction of sodium with oxygen 
C) precipitation of solute from a unsaturated solution 
D) water flowing uphill 
A) a mixture of two liquids separating into pure compounds 
B) reaction of sodium with oxygen 
C) precipitation of solute from a unsaturated solution 
D) water flowing uphill

Question 17

In figure (1)below argon atoms,represented by unshaded spheres,and neon atoms,represented by shaded spheres,are in separate compartments.Figure (2)shows the equilibrium state of the system after the stopcock separating the two compartments is opened.Assuming that argon and neon behave as ideal gases,what are the signs (+,-,or 0)of ΔH,ΔS,and ΔG for this process?

Accepted Answer

A) ΔH = +,ΔS = -,ΔG = + 
B) ΔH = 0,ΔS = +,ΔG = - 
C) ΔH = 0,ΔS = -,ΔG = + 
D) ΔH = -,ΔS = +,ΔG = - 
A) ΔH = +,ΔS = -,ΔG = + 
B) ΔH = 0,ΔS = +,ΔG = - 
C) ΔH = 0,ΔS = -,ΔG = + 
D) ΔH = -,ΔS = +,ΔG = -

Question 18

Which has the highest standard molar entropy at 25°C?

Accepted Answer

A) F2(g) 
B) N2(g) 
C) Cl2(g) 
D) I2(g) 
A) F2(g) 
B) N2(g) 
C) Cl2(g) 
D) I2(g)

Question 19

In general,as a reaction goes to equilibrium

Accepted Answer

A) ΔG decreases. 
B) ΔG°f decreases. 
C) ΔG goes to zero. 
D) ΔG° decreases. 
A) ΔG decreases. 
B) ΔG°f decreases. 
C) ΔG goes to zero. 
D) ΔG° decreases.

Question 20

A positive value of ΔG°f for a solid compound at 25°C means the

Accepted Answer

A) compound cannot exist at 25°C and 1 atm. 
B) compound must be a liquid or a gas at 25°C and 1 atm. 
C) process of forming the compound from the elements is exothermic. 
D) process of forming the compound from the stable elements at 25°C and 1 atm is nonspontaneous. 
A) compound cannot exist at 25°C and 1 atm. 
B) compound must be a liquid or a gas at 25°C and 1 atm. 
C) process of forming the compound from the elements is exothermic. 
D) process of forming the compound from the stable elements at 25°C and 1 atm is nonspontaneous.

Exam 17: Thermodynamics: Entropy, free Energy, and Equilibrium

Calculate ΔS° for the following reaction. N2(g)+ 2 O2(g)→ 2 NO2(g)

What is W in Boltzmann's formula,S = k ln W?

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

Predict the sign of ΔS for each of the following systems,which occur at constant temperature. I.The volume of 2.0 moles of Ne (g)increases from 54 L to 62 L. II.The pressure of 2.0 moles of Ne (g)increases from 0.90 atm to 1.0 atm.

Why is the sign of ΔG rather than the sign of ΔStotal generally used to determine the spontaneity of a chemical reaction?

If ΔG° is positive for a reaction,

ΔS° = -198.7 J/K for the reaction shown below.Calculate S° for NH3(g). N2(g)+ 3 H2(g)→ 2 NH3(g)

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.

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.

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?

An electron in an oxygen p orbital on which of the following would have the highest entropy?

-The figure above represents the reaction O2(g)→ 2O(g),which is nonspontaneous at 25°C.How will the spontaneity of this reaction vary with temperature? This reaction is

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

What is k in Boltzmann's formula,S = k ln W?

At high temperatures,boron carbide vaporizes according to B4C(s)⇌ 4 B(g)+ C(s) At 2500 K,the equilibrium pressure of B(g)is 0.0342 mm Hg over a mixture of 0.300 mol B4C(s)and 0.500 mol C(s).Calculate ΔG° for this process.

Which of the following processes is spontaneous?

Which has the highest standard molar entropy at 25°C?

In general,as a reaction goes to equilibrium

A positive value of ΔG°f for a solid compound at 25°C means the

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Calculate ΔS° for the following reaction. N₂(g)+ 2 O₂(g)→ 2 NO₂(g)

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

Predict the sign of ΔS for each of the following systems,which occur at constant temperature. I.The volume of 2.0 moles of Ne(g)increases from 54 L to 62 L. II.The pressure of 2.0 moles of Ne(g)increases from 0.90 atm to 1.0 atm.

Why is the sign of ΔG rather than the sign of ΔS_total generally used to determine the spontaneity of a chemical reaction?

ΔS° = -198.7 J/K for the reaction shown below.Calculate S° for NH₃(g). N₂(g)+ 3 H₂(g)→ 2 NH₃(g)

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.

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.

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?

-The figure above represents the reaction O₂(g)→ 2O(g),which is nonspontaneous at 25°C.How will the spontaneity of this reaction vary with temperature? This reaction is

At high temperatures,boron carbide vaporizes according to B₄C(s)⇌ 4 B(g)+ C(s) At 2500 K,the equilibrium pressure of B(g)is 0.0342 mm Hg over a mixture of 0.300 mol B₄C(s)and 0.500 mol C(s).Calculate ΔG° for this process.

A positive value of ΔG°_f for a solid compound at 25°C means the