Question 1

For a gas-phase equilibrium, a change in the pressure of any single reactant or product will change Kp.

Accepted Answer

A) True 
 B)False  False

Question 2

What is the mass-action expression,   c, for the following chemical reaction? PbO(s) + CO(g)   Pb(l) + CO2(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. A

Question 3

Write the mass-action expression, c, for the following chemical reaction. 3ClO2-(aq) 2ClO3-(aq) + Cl-(aq)

Accepted Answer

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

Question 4

Once a reaction system reaches equilibrium, the concentrations of reactions and products no longer change.

Accepted Answer

A) True 
 B)False

Question 5

The reaction of nitric oxide to form dinitrogen oxide and nitrogen dioxide is exothermic. 3NO(g)   N2O(g) + NO2(g) + heat
What effect will be seen if the temperature of the system at equilibrium is raised by 25°C?

Accepted Answer

A)  The partial pressure of NO will increase. 
B)  The partial pressure of NO will decrease. 
C)  The partial pressure of NO2 will increase. 
D)  The partial pressures of NO and N2O will increase. 
E)  All three partial pressures will increase. 
A)  The partial pressure of NO will increase. 
B)  The partial pressure of NO will decrease. 
C)  The partial pressure of NO2 will increase. 
D)  The partial pressures of NO and N2O will increase. 
E)  All three partial pressures will increase.

Question 6

If all the reactants and products in an equilibrium reaction are in the gas phase, then Kp = Kc.

Accepted Answer

A) True 
 B)False

Question 7

When a reaction system reaches equilibrium, the forward and reverse reactions stop.

Accepted Answer

A) True 
 B)False

Question 8

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.

Question 9

Write the mass-action expression,   c, for the following chemical reaction. Fe3+(aq) + 3OH-(aq)   Fe(OH)3(s)

Accepted Answer

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

Question 10

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 11

Consider the equilibrium reaction: H2(g) + Br2(g)   2HBr(g) Which of the following correctly describes the relationship between Kc and Kp for the reaction?

Accepted Answer

A)  Kp = Kc 
B)  Kp = (RT)Kc 
C)  Kp = (RT)2Kc 
D)  Kp = Kc / RT 
E)  Kp = Kc / (RT)2 
A)  Kp = Kc 
B)  Kp = (RT)Kc 
C)  Kp = (RT)2Kc 
D)  Kp = Kc / RT 
E)  Kp = Kc / (RT)2

Question 12

Consider the equilibrium reaction shown below. B2(g)   2B(g)
If the rate constants are: kfwd = 7.00 × 10-5s-1 and krev = 2.00 × 10-5 L mol-1 s-1, what is the value of Kc under these conditions?

Accepted Answer

A)  1.75 × 105 
B)  3.50 
C)  0.286 
D)  5.71 × 10-6 
E)  1.40 × 10-10 
A)  1.75 × 105 
B)  3.50 
C)  0.286 
D)  5.71 × 10-6 
E)  1.40 × 10-10

Question 13

A good catalyst for a reaction will speed up the forward reaction and slow down the reverse reaction.

Accepted Answer

A) True 
 B)False

Question 14

Carbon monoxide and chlorine combine in an equilibrium reaction to produce the highly toxic product, phosgene (COCl2) CO(g) + Cl2(g)   COCl2(g)
If the equilibrium constant for this reaction is Kc = 248, predict, if possible, what will happen when the reactants and product are combined with the concentrations shown.
[CO] = [Cl2] = 0.010 M; [COCl2] = 0.070 M

Accepted Answer

A)  The reaction will proceed to the right. 
B)  The reaction will proceed to the left. 
C)  The reaction is at equilibrium, and no change in concentrations will occur. 
D)  The container volume needs to be specified before a prediction can be made. 
E)  The temperature needs to be specified before a prediction can be made. 
A)  The reaction will proceed to the right. 
B)  The reaction will proceed to the left. 
C)  The reaction is at equilibrium, and no change in concentrations will occur. 
D)  The container volume needs to be specified before a prediction can be made. 
E)  The temperature needs to be specified before a prediction can be made.

Question 15

Ethane can be formed by reacting acetylene with hydrogen. C2H2(g) + 2H2(g)   C2H6(g) ΔH°rxn = -311 kJ
Under which reaction conditions would you expect to have the greatest equilibrium yield of ethane?

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

Changing the amount of a solid reactant or product in an equilibrium reaction will not affect the amounts of the other reactants and products present at equilibrium.

Accepted Answer

A) True 
 B)False

Question 17

Hydrogen sulfide can be formed in the following reaction: H2(g) + ½S2(g)   H2S(g) ΔH°rxn = -92 kJ
The equilibrium constant Kp = 106 at 1023 K. Estimate the value of Kp at 1218 K.

Accepted Answer

A)  5.05 
B)  18.8 
C)  34.7 
D)  88.9 
E)  598 
A)  5.05 
B)  18.8 
C)  34.7 
D)  88.9 
E)  598

Question 18

The reaction system CS2(g) + 4H2(g)   CH4(g) + 2H2S(g)
Is at equilibrium. Which of the following statements describes the behavior of the system if the partial pressure of hydrogen is doubled?

Accepted Answer

A)  As equilibrium is reestablished, the partial pressure of carbon disulfide increases. 
B)  As equilibrium is reestablished, the partial pressure of methane, CH4, decreases. 
C)  As equilibrium is reestablished, the partial pressure of hydrogen decreases. 
D)  As equilibrium is reestablished, the partial pressure of hydrogen sulfide decreases. 
E)  As equilibrium is reestablished, all the partial pressures will decrease. 
A)  As equilibrium is reestablished, the partial pressure of carbon disulfide increases. 
B)  As equilibrium is reestablished, the partial pressure of methane, CH4, decreases. 
C)  As equilibrium is reestablished, the partial pressure of hydrogen decreases. 
D)  As equilibrium is reestablished, the partial pressure of hydrogen sulfide decreases. 
E)  As equilibrium is reestablished, all the partial pressures will decrease.

Question 19

N2(g) + O2(g)   2NO(g) Kc = 4.8 × 10-31 2NOBr(g)   2NO(g) + Br2(g) Kc = 0.50
Given the above equilibrium constant data at 25°C, what is the value of Kc at this temperature for the reaction
2NOBr(g)   N2(g) + O2(g) + Br2(g)?

Accepted Answer

A)  2.4 × 10-31 
B)  9.6 × 10-31 
C)  1.0 × 1030 
D)  4.2 × 1030 
E)  None of these choices are correct. 
A)  2.4 × 10-31 
B)  9.6 × 10-31 
C)  1.0 × 1030 
D)  4.2 × 1030 
E)  None of these choices are correct.

Question 20

The equilibrium constant Kc for the reaction A(g) + B(g)   C(g)
Is 0.76 at 150°C. If 0.800 mol of A is added to 0.600 mol of B in a 1.00-L container at 150°C, what will be the equilibrium concentration of C?

Accepted Answer

A)  0.19 M 
B)  0.29 M 
C)  0.36 M 
D)  0.41 M 
E)  0.51 M 
A)  0.19 M 
B)  0.29 M 
C)  0.36 M 
D)  0.41 M 
E)  0.51 M

Exam 17: Equilibrium the Extent of Chemical Reactions

For a gas-phase equilibrium, a change in the pressure of any single reactant or product will change Kp.

What is the mass-action expression, c, for the following chemical reaction? PbO(s) + CO(g) Pb(l) + CO2(g)

Write the mass-action expression, c, for the following chemical reaction. 3ClO2-(aq) 2ClO3-(aq) + Cl-(aq)

Once a reaction system reaches equilibrium, the concentrations of reactions and products no longer change.

The reaction of nitric oxide to form dinitrogen oxide and nitrogen dioxide is exothermic. 3NO(g) N2O(g) + NO2(g) + heat What effect will be seen if the temperature of the system at equilibrium is raised by 25°C?

If all the reactants and products in an equilibrium reaction are in the gas phase, then Kp = Kc.

When a reaction system reaches equilibrium, the forward and reverse reactions stop.

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?

Write the mass-action expression, c, for the following chemical reaction. Fe3+(aq) + 3OH-(aq) Fe(OH)3(s)

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?

Consider the equilibrium reaction: H2(g) + Br2(g) 2HBr(g) Which of the following correctly describes the relationship between Kc and Kp for the reaction?

Consider the equilibrium reaction shown below. B2(g) 2B(g) If the rate constants are: kfwd = 7.00 × 10-5s-1 and krev = 2.00 × 10-5 L mol-1 s-1, what is the value of Kc under these conditions?

A good catalyst for a reaction will speed up the forward reaction and slow down the reverse reaction.

Ethane can be formed by reacting acetylene with hydrogen. C2H2(g) + 2H2(g) C2H6(g) ΔH°rxn = -311 kJ Under which reaction conditions would you expect to have the greatest equilibrium yield of ethane?

Changing the amount of a solid reactant or product in an equilibrium reaction will not affect the amounts of the other reactants and products present at equilibrium.

Hydrogen sulfide can be formed in the following reaction: H2(g) + ½S2(g) H2S(g) ΔH°rxn = -92 kJ The equilibrium constant Kp = 106 at 1023 K. Estimate the value of Kp at 1218 K.

The reaction system CS2(g) + 4H2(g) CH4(g) + 2H2S(g) Is at equilibrium. Which of the following statements describes the behavior of the system if the partial pressure of hydrogen is doubled?

N2(g) + O2(g) 2NO(g) Kc = 4.8 × 10-31 2NOBr(g) 2NO(g) + Br2(g) Kc = 0.50 Given the above equilibrium constant data at 25°C, what is the value of Kc at this temperature for the reaction 2NOBr(g) N2(g) + O2(g) + Br2(g)?

The equilibrium constant Kc for the reaction A(g) + B(g) C(g) Is 0.76 at 150°C. If 0.800 mol of A is added to 0.600 mol of B in a 1.00-L container at 150°C, what will be the equilibrium concentration of C?

Keys to Studying 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

For a gas-phase equilibrium, a change in the pressure of any single reactant or product will change K_p.

What is the mass-action expression, c, for the following chemical reaction? PbO(s) + CO(g) Pb(l) + CO₂(g)

Write the mass-action expression, c, for the following chemical reaction. 3ClO₂^-(aq) 2ClO₃^-(aq) + Cl^-(aq)

The reaction of nitric oxide to form dinitrogen oxide and nitrogen dioxide is exothermic. 3NO(g) N₂O(g) + NO₂(g) + heat What effect will be seen if the temperature of the system at equilibrium is raised by 25°C?

If all the reactants and products in an equilibrium reaction are in the gas phase, then K_p = K_c.

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?

Write the mass-action expression, c, for the following chemical reaction. Fe³⁺(aq) + 3OH^-(aq) Fe(OH)₃(s)

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?

Consider the equilibrium reaction: H₂(g) + Br₂(g) 2HBr(g) Which of the following correctly describes the relationship between K_c and K_p for the reaction?

Consider the equilibrium reaction shown below. B2(g) 2B(g) If the rate constants are: k_fwd = 7.00 × 10^-5s^-1 and k_rev = 2.00 × 10^-5 L mol^-1 s^-1, what is the value of K_c under these conditions?

Ethane can be formed by reacting acetylene with hydrogen. C₂H₂(g) + 2H₂(g) C₂H₆(g) ΔH°_rxn = -311 kJ Under which reaction conditions would you expect to have the greatest equilibrium yield of ethane?

Hydrogen sulfide can be formed in the following reaction: H₂(g) + ½S₂(g) H₂S(g) ΔH°rxn = -92 kJ The equilibrium constant K_p = 106 at 1023 K. Estimate the value of K_p at 1218 K.

The reaction system CS₂(g) + 4H₂(g) CH₄(g) + 2H₂S(g) Is at equilibrium. Which of the following statements describes the behavior of the system if the partial pressure of hydrogen is doubled?

N₂(g) + O₂(g) 2NO(g) K_c = 4.8 × 10^-31 2NOBr(g) 2NO(g) + Br₂(g) K_c = 0.50 Given the above equilibrium constant data at 25°C, what is the value of K_c at this temperature for the reaction 2NOBr(g) N₂(g) + O₂(g) + Br₂(g)?