Question 1

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

Accepted Answer

A) True 
 B)False

Question 2

The following reaction, in CCl4 solvent, has been studied at 25 $\degree$C.

The equilibrium constant Kc is known to be 0.141. If the initial concentration of chlorine is 0.0300 M and of bromine monochloride is 0.0200 M, what is the equilibrium concentration of bromine?

Accepted Answer

A)  1.35 *10¯3 M 
B)  2.70 * 10¯3 M 
C)  8.82 * 10¯3 M 
D)  9.70 * 10¯2 M 
E)  None of these choices is correct. 
A)  1.35 *10¯3 M 
B)  2.70 * 10¯3 M 
C)  8.82 * 10¯3 M 
D)  9.70 * 10¯2 M 
E)  None of these choices is correct.

Question 3

Consider the equilibrium:
A(s)   B(s) + C(g), $\Delta$H$\degree$rxn > 0
Predict and explain how or whether the following actions would affect this equilibrium.
A) adding more solid A
B) lowering the temperature
C) increasing the pressure on the system by reducing its volume
D) adding helium gas to increase the total pressure

Accepted Answer

a. No effect. Pure solids and liquids ha

Question 4

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 5

10.0 mL of a 0.100 mol L¯1 solution of a metal ion M2+ is mixed with 10.0 mL of a 0.100 mol l¯1 solution of a substance L. The following equilibrium is established:   At equilibrium, the concentration of L is found to be 0.0100 mol L¯1. What is the equilibrium concentration of ML22+, in mol L¯1?

Accepted Answer

A)  0.100 mol L¯1 
B)  0.050 mol L¯1 
C)  0.025 mol L¯1 
D)  0.0200 mol L¯1 
E)  0.0100 mol L¯1 
A)  0.100 mol L¯1 
B)  0.050 mol L¯1 
C)  0.025 mol L¯1 
D)  0.0200 mol L¯1 
E)  0.0100 mol L¯1

Question 6

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

Accepted Answer

A) True 
 B)False

Question 7

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

Accepted Answer

A) True 
 B)False

Question 8

Hydrogen bromide will dissociate into hydrogen and bromine gases.   What effect will a temperature increase of 50 $\degree$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

Compounds A, B, and C react according to the following equation.   At 100 $\degree$C a mixture of these gases at equilibrium showed that [A] = 0.855 M, [B] = 1.23 M, and [C] = 1.75 M. What is the value of Kc for this reaction?

Accepted Answer

A)  0.309 
B)  0.601 
C)  1.66 
D)  3.24 
E)  > 10 
A)  0.309 
B)  0.601 
C)  1.66 
D)  3.24 
E)  > 10

Question 10

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 11

Write the mass-action expression, Qc, for the following chemical reaction.

Accepted Answer

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

Question 12

The reaction of nitrogen with oxygen to form nitrogen monxide can be represented by the following equation.   At 2000 $\degree$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 is correct. 
A)  2.17 * 10¯8 
B)  4.10 * 10¯4 
C)  7.65 * 10¯2 
D)  7.75 
E)  None of these choices is correct.

Question 13

The following reaction is at equilibrium at a pressure of 1 atm, in a closed container.   Which, if any, of the following actions will decrease the concentration of CO2 gas present at equilibrium?

Accepted Answer

A)  adding N2 gas to double the pressure 
B)  adding more solid NaOH 
C)  increasing the volume of the container 
D)  lowering the temperature 
E)  None of these choices is correct. 
A)  adding N2 gas to double the pressure 
B)  adding more solid NaOH 
C)  increasing the volume of the container 
D)  lowering the temperature 
E)  None of these choices is correct.

Question 14

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

Accepted Answer

A) True 
 B)False

Question 15

Magnesium carbonate dissociates to magnesium oxide and carbon dioxide at elevated temperatures.   A reaction vessel contains these compounds in equilibrium at 300 $\degree$C. What will happen if the volume of the container is reduced by 25% at 300$\degree$C?

Accepted Answer

A)  The partial pressure of carbon dioxide present at equilibrium will increase. 
B)  The partial pressure of carbon dioxide present at equilibrium will decrease. 
C)  The partial pressure of carbon dioxide at equilibrium will be unchanged. 
D)  The equilibrium constant will have to decrease to compensate for the decrease in volume. 
E)  More information is needed in order to make a valid judgment. 
A)  The partial pressure of carbon dioxide present at equilibrium will increase. 
B)  The partial pressure of carbon dioxide present at equilibrium will decrease. 
C)  The partial pressure of carbon dioxide at equilibrium will be unchanged. 
D)  The equilibrium constant will have to decrease to compensate for the decrease in volume. 
E)  More information is needed in order to make a valid judgment.

Question 16

The reaction system   is at equilibrium. Which of the following statements describes the behavior of the system if the partial pressure of carbon disulfide is reduced?

Accepted Answer

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

Question 17

A mixture of 0.600 mol of bromine and 1.600 mol of iodine is placed into a rigid 1.000-L container at 350 $\degree$C.   When the mixture has come to equilibrium, the concentration of iodine monobromide is 1.190 M. What is the equilibrium constant for this reaction at 350 $\degree$C?

Accepted Answer

A)  3.55 * 10¯3 
B)  1.24 
C)  1.47 
D)  282 
E)  325 
A)  3.55 * 10¯3 
B)  1.24 
C)  1.47 
D)  282 
E)  325

Question 18

Write the expressions for Kc and Kp for the reaction

Accepted Answer

Question 19

The following reaction is at equilibrium in a closed container.   Which, if any, of the following actions will lead to an increase in the pressure of H2O present at equilibrium?

Accepted Answer

A)  increasing the volume of the container 
B)  decreasing the volume of the container 
C)  adding a catalyst 
D)  removing some solid CuSO4 
E)  None of these choices is correct. 
A)  increasing the volume of the container 
B)  decreasing the volume of the container 
C)  adding a catalyst 
D)  removing some solid CuSO4 
E)  None of these choices is correct.

Question 20

Ethane can be formed by reacting acetylene with hydrogen.   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 is correct, unless a catalyst is present. 
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 is correct, unless a catalyst is present.

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

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.

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

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

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

Write the mass-action expression, Q_c, for the following chemical reaction.

The following reaction is at equilibrium at a pressure of 1 atm, in a closed container. Which, if any, of the following actions will decrease the concentration of CO₂ gas present at equilibrium?

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

The reaction system is at equilibrium. Which of the following statements describes the behavior of the system if the partial pressure of carbon disulfide is reduced?

Write the expressions for K_c and K_p for the reaction

The following reaction is at equilibrium in a closed container. Which, if any, of the following actions will lead to an increase in the pressure of H₂O present at equilibrium?

Ethane can be formed by reacting acetylene with hydrogen. Under which reaction conditions would you expect to have the greatest equilibrium yield of ethane?

Keys to the Study of Chemistry

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 the Direction of Chemical Reactions

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

The Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

Exam 17: Equilibrium: the Extent of Chemical Reactions

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

The following reaction, in CCl4 solvent, has been studied at 25 °\degree° C. The equilibrium constant Kc is known to be 0.141. If the initial concentration of chlorine is 0.0300 M and of bromine monochloride is 0.0200 M, what is the equilibrium concentration of bromine?

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.

10.0 mL of a 0.100 mol L¯1 solution of a metal ion M2+ is mixed with 10.0 mL of a 0.100 mol l¯1 solution of a substance L. The following equilibrium is established: At equilibrium, the concentration of L is found to be 0.0100 mol L¯1. What is the equilibrium concentration of ML22+, in mol L¯1?

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

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

Hydrogen bromide will dissociate into hydrogen and bromine gases. What effect will a temperature increase of 50 °\degree° C have on this system at equilibrium?

Compounds A, B, and C react according to the following equation. At 100 °\degree° C a mixture of these gases at equilibrium showed that [A] = 0.855 M, [B] = 1.23 M, and [C] = 1.75 M. What is the value of Kc for this reaction?

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

Write the mass-action expression, Qc, for the following chemical reaction.

The reaction of nitrogen with oxygen to form nitrogen monxide can be represented by the following equation. At 2000 °\degree° C, the equilibrium constant, Kc, has a value of 4.10 * 10¯4. What is the value of Kp?

The following reaction is at equilibrium at a pressure of 1 atm, in a closed container. Which, if any, of the following actions will decrease the concentration of CO2 gas present at equilibrium?

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

Magnesium carbonate dissociates to magnesium oxide and carbon dioxide at elevated temperatures. A reaction vessel contains these compounds in equilibrium at 300 °\degree° C. What will happen if the volume of the container is reduced by 25% at 300 °\degree° C?

The reaction system is at equilibrium. Which of the following statements describes the behavior of the system if the partial pressure of carbon disulfide is reduced?

A mixture of 0.600 mol of bromine and 1.600 mol of iodine is placed into a rigid 1.000-L container at 350 °\degree° C. When the mixture has come to equilibrium, the concentration of iodine monobromide is 1.190 M. What is the equilibrium constant for this reaction at 350 °\degree° C?

Write the expressions for Kc and Kp for the reaction

The following reaction is at equilibrium in a closed container. Which, if any, of the following actions will lead to an increase in the pressure of H2O present at equilibrium?

Ethane can be formed by reacting acetylene with hydrogen. Under which reaction conditions would you expect to have the greatest equilibrium yield of ethane?

Keys to the Study of Chemistry

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 the Direction of Chemical Reactions

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

The Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

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

Write the mass-action expression, Q_c, for the following chemical reaction.

The following reaction is at equilibrium at a pressure of 1 atm, in a closed container. Which, if any, of the following actions will decrease the concentration of CO₂ gas present at equilibrium?

Write the expressions for K_c and K_p for the reaction

The following reaction is at equilibrium in a closed container. Which, if any, of the following actions will lead to an increase in the pressure of H₂O present at equilibrium?