Question 1

Write the mass-action expression, Qc, for the following chemical reaction. MgO(s) + SO2(g) + ½O2(g) ⇄ MgSO4(s)

Accepted Answer

A)    
B)    
C)    
D)    
E) None of these choices are correct. 
A)    
B)    
C)    
D)    
E) None of these choices are correct.

Question 2

Sodium hydrogen carbonate decomposes above 110°C to form sodium carbonate, water, and carbon dioxide. 2NaHCO3(s) ⇄ Na2CO3(s) + H2O(g) + CO2(g)
One thousand grams of sodium hydrogen carbonate are added to a reaction vessel, the temperature is increased to 200°C, and the system comes to equilibrium. What happens in this system if another 50 g of sodium carbonate are now added?

Accepted Answer

A) The partial pressure of carbon dioxide will increase. 
B) The partial pressure of carbon dioxide will decrease. 
C) The partial pressure of carbon dioxide will be unchanged. 
D) The amounts of all products will be greater when equilibrium is reestablished. 
E) None of these choices are correct. 
A) The partial pressure of carbon dioxide will increase. 
B) The partial pressure of carbon dioxide will decrease. 
C) The partial pressure of carbon dioxide will be unchanged. 
D) The amounts of all products will be greater when equilibrium is reestablished. 
E) None of these choices are correct.

Question 3

A chemical reaction will reach equilibrium when the limiting reactant is used up.

Accepted Answer

A) True 
 B)False

Question 4

At 25°C, the equilibrium constant Kc for the reaction 2A(g) ⇄ B(g) + C(g)
Is 0.035. A mixture of 8.00 moles of B and 12.00 moles of C in a 20.0 L container is allowed to come to equilibrium. What is the equilibrium concentration of A?

Accepted Answer

A) < 0.100 M 
B) 0.339 M 
C) 0.678 M 
D) 6.78 M 
E) 13.56 M 
A) < 0.100 M 
B) 0.339 M 
C) 0.678 M 
D) 6.78 M 
E) 13.56 M

Question 5

If Q > K, more products need to be formed as the reaction proceeds to equilibrium.

Accepted Answer

A) True 
 B)False

Question 6

The reaction of nitrogen with oxygen to form nitrogen monoxide can be represented by the following equation. N2(g) + O2(g) ⇄ 2NO(g)
At 2000°C, the equilibrium constant, Kc, has a value of 4.10 × 10−4. What is the value of Kp?

Accepted Answer

A) 2.17 × 10 −8 
B) 4.10 × 10 −4 
C) 7.65 × 10 −2 
D) 7.75 
E) None of these choices are correct. 
A) 2.17 × 10 −8 
B) 4.10 × 10 −4 
C) 7.65 × 10 −2 
D) 7.75 
E) None of these choices are correct.

Question 7

Write the mass-action expression, Qc, for the following chemical reaction. 2Cu2+(aq) + 4I−(aq) ⇄ 2CuI(s) + I2(aq)

Accepted Answer

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

Question 8

In a chemical reaction, if the starting concentrations of reactants are increased, then the equilibrium constant Kc will also increase.

Accepted Answer

A) True 
 B)False

Question 9

The equilibrium constant, Kp, for the reaction CO(g) + H2O(g) ⇄ CO2(g) + H2(g)
At 986°C is 0.63. A rigid cylinder at that temperature contains 1.2 atm of carbon monoxide, 0.20 atm of water vapor, 0.30 atm of carbon dioxide, and 0.27 atm of hydrogen. Is the system at equilibrium?

Accepted Answer

A) Yes. 
B) No, the forward reaction must proceed to establish equilibrium. 
C) No, the reverse reaction must proceed to establish equilibrium. 
D) Need to know the volume of the container before deciding. 
E) Need to know the starting concentrations of all substances before deciding. 
A) Yes. 
B) No, the forward reaction must proceed to establish equilibrium. 
C) No, the reverse reaction must proceed to establish equilibrium. 
D) Need to know the volume of the container before deciding. 
E) Need to know the starting concentrations of all substances before deciding.

Question 10

Nitrogen dioxide decomposes according to the reaction 2NO2(g) ⇄ 2NO(g) + O2(g)
Where Kp = 4.48 × 10−13 at 25°C. What is the value for Kc?

Accepted Answer

A) 1.81 × 10 −16 
B) 1.83 × 10 −14 
C) 4.48 × 10 −13 
D) 1.10 × 10 −11 
E) 1.11 × 10 −9 
A) 1.81 × 10 −16 
B) 1.83 × 10 −14 
C) 4.48 × 10 −13 
D) 1.10 × 10 −11 
E) 1.11 × 10 −9

Question 11

What is the mass-action expression, Qc, for the following chemical reaction? Cu2+(aq) + 4NH3(aq) ⇄ Cu(NH3)42+(aq)

Accepted Answer

A)    
B)    
C)    
D)    
E) None of these choices are correct. 
A)    
B)    
C)    
D)    
E) None of these choices are correct.

Question 12

The following reaction is at equilibrium at one atmosphere, in a closed container. NaOH(s) + CO2(g) ⇄ NaHCO3(s)
Which, if any, of the following actions will decrease the total amount of CO2 gas present at equilibrium?

Accepted Answer

A) Adding N 2 gas to double the pressure 
B) Adding more solid NaOH 
C) Decreasing the volume of the container 
D) Removing half of the solid NaHCO 3 
E) None of these choices are correct. 
A) Adding N 2 gas to double the pressure 
B) Adding more solid NaOH 
C) Decreasing the volume of the container 
D) Removing half of the solid NaHCO 3 
E) None of these choices are correct.

Question 13

An equilibrium is established in which both the forward (fwd) and the reverse (rev) reactions are elementary. If the equilibrium constant Kc = 1.6 × 10−2 and the rate constant kfwd = 8.0 × 10−7 s−1 what is the value of krev?

Accepted Answer

A) 1.3 × 10 −8 s −1 
B) 7.8 × 10 7 s −1 
C) 2 × 10 4 s −1 
D) 5.0 × 10 −5 s −1 
E) None of these choices are correct. 
A) 1.3 × 10 −8 s −1 
B) 7.8 × 10 7 s −1 
C) 2 × 10 4 s −1 
D) 5.0 × 10 −5 s −1 
E) None of these choices are correct.

Question 14

What is the mass-action expression, Qp, for the following reaction? SbF5(g) + 4Cl2(g) ⇄ SbCl3(g) + 5ClF(g)

Accepted Answer

A)    
B)    
C)    
D)    
E) None of these choices are correct. 
A)    
B)    
C)    
D)    
E) None of these choices are correct.

Question 15

Nitrogen dioxide can dissociate to nitric oxide and oxygen. 2NO2(g) ⇄ 2NO(g) + O2(g) ΔH°rxn = +114 kJ
Under which reaction conditions would you expect to produce the largest amount of oxygen?

Accepted Answer

A) High temperature, high pressure 
B) Low temperature, high pressure 
C) High temperature, low pressure 
D) Low temperature, low pressure 
E) None of these choices are correct. 
A) High temperature, high pressure 
B) Low temperature, high pressure 
C) High temperature, low pressure 
D) Low temperature, low pressure 
E) None of these choices are correct.

Question 16

In order to write the correct mass-action expression for a reaction one must

Accepted Answer

A) know the kinetic rate law for the reaction. 
B) know the mechanism for the reaction. 
C) have a properly balanced chemical equation. 
D) have values for the concentrations of the reactants. 
E) know the limiting reactant. 
A) know the kinetic rate law for the reaction. 
B) know the mechanism for the reaction. 
C) have a properly balanced chemical equation. 
D) have values for the concentrations of the reactants. 
E) know the limiting reactant.

Question 17

Which of the following has an effect on the magnitude of the equilibrium constant?

Accepted Answer

A) Removing products as they are formed 
B) Adding more of a reactant 
C) Adding a catalyst 
D) Increasing the pressure, in a gas-phase reaction 
E) Change in temperature 
A) Removing products as they are formed 
B) Adding more of a reactant 
C) Adding a catalyst 
D) Increasing the pressure, in a gas-phase reaction 
E) Change in temperature

Question 18

Hydrogen bromide will dissociate into hydrogen and bromine gases. 2HBr(g) ⇄ H2(g) + Br2(g) ΔH°rxn = 68 kJ
What effect will a temperature increase of 50°C have on this system at equilibrium?

Accepted Answer

A) The partial pressure of hydrogen bromide will increase. 
B) The partial pressure of hydrogen will increase. 
C) The partial pressure of hydrogen bromide and bromine will increase. 
D) There will be no effect on the partial pressure of any of the gases. 
E) Need to know the initial pressure, volume, and temperature before any of the above predictions can be made. 
A) The partial pressure of hydrogen bromide will increase. 
B) The partial pressure of hydrogen will increase. 
C) The partial pressure of hydrogen bromide and bromine will increase. 
D) There will be no effect on the partial pressure of any of the gases. 
E) Need to know the initial pressure, volume, and temperature before any of the above predictions can be made.

Exam 17: Equilibrium: the Extent of Chemical Reactions

Write the mass-action expression, Qc, for the following chemical reaction. MgO(s) + SO2(g) + ½O2(g) ⇄ MgSO4(s)

A chemical reaction will reach equilibrium when the limiting reactant is used up.

At 25°C, the equilibrium constant Kc for the reaction 2A(g) ⇄ B(g) + C(g) Is 0.035. A mixture of 8.00 moles of B and 12.00 moles of C in a 20.0 L container is allowed to come to equilibrium. What is the equilibrium concentration of A?

If Q > K, more products need to be formed as the reaction proceeds to equilibrium.

The reaction of nitrogen with oxygen to form nitrogen monoxide can be represented by the following equation. N2(g) + O2(g) ⇄ 2NO(g) At 2000°C, the equilibrium constant, Kc, has a value of 4.10 × 10−4. What is the value of Kp?

Write the mass-action expression, Qc, for the following chemical reaction. 2Cu2+(aq) + 4I−(aq) ⇄ 2CuI(s) + I2(aq)

In a chemical reaction, if the starting concentrations of reactants are increased, then the equilibrium constant Kc will also increase.

The equilibrium constant, Kp, for the reaction CO(g) + H2O(g) ⇄ CO2(g) + H2(g) At 986°C is 0.63. A rigid cylinder at that temperature contains 1.2 atm of carbon monoxide, 0.20 atm of water vapor, 0.30 atm of carbon dioxide, and 0.27 atm of hydrogen. Is the system at equilibrium?

Nitrogen dioxide decomposes according to the reaction 2NO2(g) ⇄ 2NO(g) + O2(g) Where Kp = 4.48 × 10−13 at 25°C. What is the value for Kc?

What is the mass-action expression, Qc, for the following chemical reaction? Cu2+(aq) + 4NH3(aq) ⇄ Cu(NH3)42+(aq)

The following reaction is at equilibrium at one atmosphere, in a closed container. NaOH(s) + CO2(g) ⇄ NaHCO3(s) Which, if any, of the following actions will decrease the total amount of CO2 gas present at equilibrium?

An equilibrium is established in which both the forward (fwd) and the reverse (rev) reactions are elementary. If the equilibrium constant Kc = 1.6 × 10−2 and the rate constant kfwd = 8.0 × 10−7 s−1 what is the value of krev?

What is the mass-action expression, Qp, for the following reaction? SbF5(g) + 4Cl2(g) ⇄ SbCl3(g) + 5ClF(g)

Nitrogen dioxide can dissociate to nitric oxide and oxygen. 2NO2(g) ⇄ 2NO(g) + O2(g) ΔH°rxn = +114 kJ Under which reaction conditions would you expect to produce the largest amount of oxygen?

In order to write the correct mass-action expression for a reaction one must

Which of the following has an effect on the magnitude of the equilibrium constant?

Hydrogen bromide will dissociate into hydrogen and bromine gases. 2HBr(g) ⇄ H2(g) + Br2(g) ΔH°rxn = 68 kJ What effect will a temperature increase of 50°C have on this system at equilibrium?

Keys to the Study of Chemistry: Definitions, Units, and Problem Solving

The Components of Matter

Stoichiometry of Formulas and Equations

Three Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids, Solids, and Phase Changes

The Properties of Mixtures: Solutions and Colloids

Periodic Patterns in the Main-Group Elements

Organic Compounds and the Atomic Properties of Carbon

Kinetics: Rates and Mechanisms of Chemical Reactions

Acid-Base Equilibria

Ionic Equilibria in Aqueous Systems

Thermodynamics: Entropy, Free Energy, and Reaction Direction

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

Write the mass-action expression, Q_c, for the following chemical reaction. MgO(s) + SO₂(g) + ½O₂(g) ⇄ MgSO₄(s)

At 25°C, the equilibrium constant K_c for the reaction 2A(g) ⇄ B(g) + C(g) Is 0.035. A mixture of 8.00 moles of B and 12.00 moles of C in a 20.0 L container is allowed to come to equilibrium. What is the equilibrium concentration of A?

The reaction of nitrogen with oxygen to form nitrogen monoxide can be represented by the following equation. N₂(g) + O₂(g) ⇄ 2NO(g) At 2000°C, the equilibrium constant, K_c, has a value of 4.10 × 10⁻⁴. What is the value of K_p?

Write the mass-action expression, Q_c, for the following chemical reaction. 2Cu²⁺(aq) + 4I⁻(aq) ⇄ 2CuI(s) + I₂(aq)

In a chemical reaction, if the starting concentrations of reactants are increased, then the equilibrium constant K_c will also increase.

The equilibrium constant, K_p, for the reaction CO(g) + H₂O(g) ⇄ CO₂(g) + H₂(g) At 986°C is 0.63. A rigid cylinder at that temperature contains 1.2 atm of carbon monoxide, 0.20 atm of water vapor, 0.30 atm of carbon dioxide, and 0.27 atm of hydrogen. Is the system at equilibrium?

Nitrogen dioxide decomposes according to the reaction 2NO₂(g) ⇄ 2NO(g) + O₂(g) Where K_p = 4.48 × 10⁻¹³ at 25°C. What is the value for K_c?

What is the mass-action expression, Q_c, for the following chemical reaction? Cu²⁺(aq) + 4NH₃(aq) ⇄ Cu(NH₃)₄²⁺(aq)

The following reaction is at equilibrium at one atmosphere, in a closed container. NaOH(s) + CO₂(g) ⇄ NaHCO₃(s) Which, if any, of the following actions will decrease the total amount of CO₂ gas present at equilibrium?

An equilibrium is established in which both the forward (fwd) and the reverse (rev) reactions are elementary. If the equilibrium constant K_c = 1.6 × 10⁻² and the rate constant k_fwd = 8.0 × 10⁻⁷s⁻¹what is the value of k_rev?

What is the mass-action expression, Q_p, for the following reaction? SbF₅(g) + 4Cl₂(g) ⇄ SbCl₃(g) + 5ClF(g)

Nitrogen dioxide can dissociate to nitric oxide and oxygen. 2NO₂(g) ⇄ 2NO(g) + O₂(g) ΔH°_rxn = +114 kJ Under which reaction conditions would you expect to produce the largest amount of oxygen?

Hydrogen bromide will dissociate into hydrogen and bromine gases. 2HBr(g) ⇄ H₂(g) + Br₂(g) ΔH°_rxn = 68 kJ What effect will a temperature increase of 50°C have on this system at equilibrium?