Question 1

Chemical reactions generally reach equilibrium because one of the reactants is used up.

Accepted Answer

A) True 
 B)False

Question 2

H2SO3(aq)  ⇄ HSO3(aq)  + H+(aq)  Kc = 1.4 × 10−2 H2SO3(aq)  ⇄ SO32−(aq)  + 2H+(aq)  Kc = 9.1 × 10−10
Given the above equilibrium constant data at 25°C, what is the value of Kc at this temperature for the reaction
HSO3−(aq)  ⇄ SO32−(aq)  + H+(aq) ?

Accepted Answer

A)  6.5 ×10 −8
B)  1.3 × 10 −11
C)  7.8 × 10 10
D)  1.5 × 10 7
E)  None of these choices are correct.F) A) and E)
G) D) and E)

Question 3

Compounds A, B, and C react according to the following equation. 3A(g)  + 2B(g)  ⇄ 2C(g) 
At 100°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)  > 10F) A) and E)
G) A) and C)

Question 4

When a chemical system is at equilibrium,

Accepted Answer

A)  the concentrations of the reactants are equal to the concentrations of the products.
B)  the concentrations of the reactants and products have reached constant values.
C)  the forward and reverse reactions have stopped.
D)  the reaction quotient, Q, has reached a maximum.
E)  the reaction quotient, Q, has reached a minimum.F) None of the above
G) C) and E)

Question 5

At 450°C, tert-butyl alcohol decomposes into water and isobutene. (CH3) 3COH(g)  ⇄ (CH3) 2CCH2(g)  + H2O(g) 
A reaction vessel contains these compounds at equilibrium. What will happen if the volume of the container is reduced by 50% at constant temperature?

Accepted Answer

A)  The forward reaction will proceed to reestablish equilibrium.
B)  The reverse reaction will proceed to reestablish equilibrium.
C)  No change occurs.
D)  The equilibrium constant will increase.
E)  The equilibrium constant will decrease.F) A) and B)
G) A) and C)

Question 6

Consider the reactions of cadmium with the thiosulfate anion. Cd2+(aq)  + S2O32−(aq)  ⇄ Cd(S2O3) (aq)  K1 = 8.3 × 103
Cd(S2O3) (aq)  + S2O32−(aq)  ⇄ Cd(S2O3) 22−(aq)  K2 = 2.5 × 102
What is the value for the equilibrium constant for the following reaction?
Cd2+(aq)  + 2S2O32−(aq)  ⇄ Cd(S2O3) 22−(aq)

Accepted Answer

A)  0.030
B)  33
C)  8.1 × 10 3
D)  8.6 × 10 3
E)  2.1 × 10 6F) A) and B)
G) B) and E)

Question 7

Magnesium hydroxide is used in several antacid formulations. When it is added to water it dissociates into magnesium and hydroxide ions. Mg(OH) 2(s)  ⇄ Mg2+(aq)  + 2OH−(aq) 
The equilibrium constant at 25°C is 8.9 × 10−12. One hundred grams of magnesium hydroxide is added to 1.00 L of water and equilibrium is established. What happens to the solution if another 10 grams of Mg(OH) 2 are now added to the mixture?

Accepted Answer

A)  The hydroxide ion concentration will decrease.
B)  The hydroxide ion concentration will increase.
C)  The hydroxide ion concentration will be unchanged.
D)  The solution will become supersaturated.
E)  None of these choices are correct.F) B) and D)
G) A) and C)

Question 8

About half of the sodium carbonate produced is used in making glass products because it lowers the melting point of sand, the major component of glass. When sodium carbonate is added to water it hydrolyses according to the following reactions. CO32−(aq)  + H2O(l)  ⇄ HCO3−(aq)  + OH−(aq)  K1
HCO3(aq)  + H2O(l)  ⇄ H2CO3(aq)  + OH−(aq)  K2
These can be combined to yield
CO32−(aq)  + 2H2O(l)  ⇄ H2CO3(aq)  + 2OH−(aq)  K3
What is the value of K3?

Accepted Answer

A)  K 1 × K 2
B)  K 1 ÷ K 2
C)  K 1 + K 2
D)  K 1 − K 2
E)  ( K 1 K 2) 2F) D) and E)
G) C) and E)

Question 9

At 500°C the equilibrium constant, Kp, is 4.00 × 10−4 for the equilibrium: 2HCN(g)  ⇄ H2(g)  + C2N2(g) 
What is Kp for the following reaction?
H2(g)  + C2N2(g)  ⇄ 2HCN(g)

Accepted Answer

A)  2.00 × 10 −4
B)  −4.00 × 10 −4
C)  1.25 × 10 3
D)  2.50 × 10 3
E)  4.00 × 10 4F) A) and B)
G) B) and E)

Question 10

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)  598F) C) and D)
G) C) and E)

Question 11

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

Accepted Answer

A) True 
 B)False

Question 12

Although a system may be at equilibrium, the rate constants of the forward and reverse reactions will in general be different.

Accepted Answer

A) True 
 B)False

Question 13

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 × 10 30
D)  4.2 × 10 30
E)  None of these choices are correct.F) A) and E)
G) D) and E)

Question 14

Nitric oxide and bromine were allowed to react in a sealed container. When equilibrium was reached PNO = 0.526 atm, NO = 0.526 atm,   = 1.59 atm, and PNOBr = 7.68 atm. Calculate Kp for the reaction. 2NO(g)  + Br2(g)  ⇄ 2NOBr(g)  A) 7.45 × 10 −3 B) 0.109 C) 9.18 D) 91.8 E) 134" class="answers-bank-image d-inline" rel="preload" > = 1.59 atm, and PNOBr = 7.68 atm. Calculate Kp for the reaction.
2NO(g)  + Br2(g)  ⇄ 2NOBr(g)

Accepted Answer

A)  7.45 × 10 −3
B)  0.109
C)  9.18
D)  91.8
E)  134F) B) and E)
G) C) and E)

Question 15

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 16

For some gas-phase reactions, Kp = Kc.

Accepted Answer

A) True 
 B)False

Question 17

The equilibrium constant Kc for the reaction PCl3(g)  + Cl2(g)  ⇄ PCl5(g) 
Is 49 at 230°C. If 0.70 mol of PCl3 is added to 0.70 mol of Cl2 in a 1.00-L reaction vessel at 230°C, what is the concentration of PCl3 when equilibrium has been established?

Accepted Answer

A)  0.049 M
B)  0.11 M
C)  0.30 M
D)  0.59 M
E)  0.83 MF) A) and B)
G) B) and D)

Question 18

The following reaction is at equilibrium at a pressure of 1 atm, in a closed container. NaOH(s)  + CO2(g)  ⇄ NaHCO3(s)  ΔH°rxn 2 gas present at equilibrium?

Accepted Answer

A)  Adding N 2 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 are correct.F) A) and D)
G) A) and E)

Question 19

Methanol can be synthesized by combining carbon monoxide and hydrogen. CO(g)  + 2H2(g)  ⇄ CH3OH(g)  ΔH°rxn = −90.7 kJ
A reaction vessel contains these compounds at equilibrium. What effect will be seen when equilibrium is re-established after decreasing the temperature by 45°C?

Accepted Answer

A)  All the partial pressures will decrease.
B)  The partial pressure of methanol will decrease.
C)  The partial pressures of hydrogen and methanol will decrease.
D)  The partial pressure of hydrogen will increase.
E)  The partial pressure of carbon monoxide will decrease.F) A) and B)
G) C) and D)

Question 20

The reaction quotient for a gas phase reaction has a value of 2000. If the number of moles of reactants in the reaction equation is equal to that of the products, which of the following statements is definitely TRUE?

Accepted Answer

A)  The reaction must proceed to the left to establish equilibrium.
B)  The reaction must proceed to the right to establish equilibrium.
C)  When the system is at equilibrium, the concentrations of the products will be much larger than the concentrations of the reactants.
D)  The concentrations of the products are generally larger than the concentrations of the reactants.
E)  None of these choices are correct.F) None of the above
G) A) and D)

Exam 17: Equilibrium: the Extent of Chemical Reactions

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

Correct Answer
verified

Chemical reactions generally reach equilibrium because one of the reactants is used up.

Correct Answer
verified

Correct Answer
verified

Methanol can be synthesized by combining carbon monoxide and hydrogen. CO(g) + 2H₂(g) ⇄ CH₃OH(g) ΔH°_rxn = −90.7 kJ A reaction vessel contains these compounds at equilibrium. What effect will be seen when equilibrium is re-established after decreasing the temperature by 45°C?

Correct Answer
verified

H₂SO₃(aq) ⇄ HSO₃(aq) + H⁺(aq) K_c = 1.4 × 10⁻² H₂SO₃(aq) ⇄ SO₃²⁻(aq) + 2H⁺(aq) K_c = 9.1 × 10⁻¹⁰ Given the above equilibrium constant data at 25°C, what is the value of K_c at this temperature for the reaction HSO₃⁻(aq) ⇄ SO₃²⁻(aq) + H⁺(aq) ?

Correct Answer
verified

The equilibrium constant K_c for the reaction PCl₃(g) + Cl₂(g) ⇄ PCl₅(g) Is 49 at 230°C. If 0.70 mol of PCl₃is added to 0.70 mol of Cl₂in a 1.00-L reaction vessel at 230°C, what is the concentration of PCl₃when equilibrium has been established?

Correct Answer
verified

When a chemical system is at equilibrium,

Correct Answer
verified

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

Correct Answer
verified

Nitric oxide and bromine were allowed to react in a sealed container. When equilibrium was reached P_NO = 0.526 atm, = 1.59 atm, and P_NOBr = 7.68 atm. Calculate K_p for the reaction. 2NO(g) + Br₂(g) ⇄ 2NOBr(g)

Correct Answer
verified

At 500°C the equilibrium constant, K_p, is 4.00 × 10⁻⁴ for the equilibrium: 2HCN(g) ⇄ H₂(g) + C₂N₂(g) What is K_p for the following reaction? H₂(g) + C₂N₂(g) ⇄ 2HCN(g)

Correct Answer
verified

The reaction quotient for a gas phase reaction has a value of 2000. If the number of moles of reactants in the reaction equation is equal to that of the products, which of the following statements is definitely TRUE?

Correct Answer
verified

Correct Answer
verified

Although a system may be at equilibrium, the rate constants of the forward and reverse reactions will in general be different.

Correct Answer
verified

The following reaction is at equilibrium at a pressure of 1 atm, in a closed container. NaOH(s) + CO₂(g) ⇄ NaHCO₃(s) ΔH°_rxn < 0 Which, if any, of the following actions will decrease the concentration of CO₂ gas present at equilibrium?

Correct Answer
verified

At 450°C, tert-butyl alcohol decomposes into water and isobutene. (CH₃) ₃COH(g) ⇄ (CH₃) ₂CCH₂(g) + H₂O(g) A reaction vessel contains these compounds at equilibrium. What will happen if the volume of the container is reduced by 50% at constant temperature?

Correct Answer
verified

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) ?

Correct Answer
verified

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.

Correct Answer
verified

Compounds A, B, and C react according to the following equation. 3A(g) + 2B(g) ⇄ 2C(g) At 100°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 K_c for this reaction?

Correct Answer
verified

For some gas-phase reactions, K_p = K_c.

Correct Answer
verified

Correct Answer
verified

Exam 17: Equilibrium: the Extent of Chemical Reactions

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

Correct AnswerverifiedShow Answer

Chemical reactions generally reach equilibrium because one of the reactants is used up.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Methanol can be synthesized by combining carbon monoxide and hydrogen. CO(g) + 2H2(g) ⇄ CH3OH(g) ΔH°rxn = −90.7 kJ A reaction vessel contains these compounds at equilibrium. What effect will be seen when equilibrium is re-established after decreasing the temperature by 45°C?

Correct AnswerverifiedShow Answer

H2SO3(aq) ⇄ HSO3(aq) + H+(aq) Kc = 1.4 × 10−2 H2SO3(aq) ⇄ SO32−(aq) + 2H+(aq) Kc = 9.1 × 10−10 Given the above equilibrium constant data at 25°C, what is the value of Kc at this temperature for the reaction HSO3−(aq) ⇄ SO32−(aq) + H+(aq) ?

Correct AnswerverifiedShow Answer

The equilibrium constant Kc for the reaction PCl3(g) + Cl2(g) ⇄ PCl5(g) Is 49 at 230°C. If 0.70 mol of PCl3 is added to 0.70 mol of Cl2 in a 1.00-L reaction vessel at 230°C, what is the concentration of PCl3 when equilibrium has been established?

Correct AnswerverifiedShow Answer

When a chemical system is at equilibrium,

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Nitric oxide and bromine were allowed to react in a sealed container. When equilibrium was reached PNO = 0.526 atm, = 1.59 atm, and PNOBr = 7.68 atm. Calculate Kp for the reaction. 2NO(g) + Br2(g) ⇄ 2NOBr(g)

Correct AnswerverifiedShow Answer

At 500°C the equilibrium constant, Kp, is 4.00 × 10−4 for the equilibrium: 2HCN(g) ⇄ H2(g) + C2N2(g) What is Kp for the following reaction? H2(g) + C2N2(g) ⇄ 2HCN(g)

Correct AnswerverifiedShow Answer

The reaction quotient for a gas phase reaction has a value of 2000. If the number of moles of reactants in the reaction equation is equal to that of the products, which of the following statements is definitely TRUE?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Although a system may be at equilibrium, the rate constants of the forward and reverse reactions will in general be different.

Correct AnswerverifiedShow Answer

The following reaction is at equilibrium at a pressure of 1 atm, in a closed container. NaOH(s) + CO2(g) ⇄ NaHCO3(s) ΔH°rxn < 0 Which, if any, of the following actions will decrease the concentration of CO2 gas present at equilibrium?

Correct AnswerverifiedShow Answer

At 450°C, tert-butyl alcohol decomposes into water and isobutene. (CH3) 3COH(g) ⇄ (CH3) 2CCH2(g) + H2O(g) A reaction vessel contains these compounds at equilibrium. What will happen if the volume of the container is reduced by 50% at constant temperature?

Correct AnswerverifiedShow Answer

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) ?

Correct AnswerverifiedShow Answer

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.

Correct AnswerverifiedShow Answer

Compounds A, B, and C react according to the following equation. 3A(g) + 2B(g) ⇄ 2C(g) At 100°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?

Correct AnswerverifiedShow Answer

For some gas-phase reactions, Kp = Kc.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Methanol can be synthesized by combining carbon monoxide and hydrogen. CO(g) + 2H₂(g) ⇄ CH₃OH(g) ΔH°_rxn = −90.7 kJ A reaction vessel contains these compounds at equilibrium. What effect will be seen when equilibrium is re-established after decreasing the temperature by 45°C?

Correct Answer
verified

H₂SO₃(aq) ⇄ HSO₃(aq) + H⁺(aq) K_c = 1.4 × 10⁻² H₂SO₃(aq) ⇄ SO₃²⁻(aq) + 2H⁺(aq) K_c = 9.1 × 10⁻¹⁰ Given the above equilibrium constant data at 25°C, what is the value of K_c at this temperature for the reaction HSO₃⁻(aq) ⇄ SO₃²⁻(aq) + H⁺(aq) ?

Correct Answer
verified

The equilibrium constant K_c for the reaction PCl₃(g) + Cl₂(g) ⇄ PCl₅(g) Is 49 at 230°C. If 0.70 mol of PCl₃is added to 0.70 mol of Cl₂in a 1.00-L reaction vessel at 230°C, what is the concentration of PCl₃when equilibrium has been established?

Correct Answer
verified

Correct Answer
verified

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

Correct Answer
verified

Nitric oxide and bromine were allowed to react in a sealed container. When equilibrium was reached P_NO = 0.526 atm, = 1.59 atm, and P_NOBr = 7.68 atm. Calculate K_p for the reaction. 2NO(g) + Br₂(g) ⇄ 2NOBr(g)

Correct Answer
verified

At 500°C the equilibrium constant, K_p, is 4.00 × 10⁻⁴ for the equilibrium: 2HCN(g) ⇄ H₂(g) + C₂N₂(g) What is K_p for the following reaction? H₂(g) + C₂N₂(g) ⇄ 2HCN(g)

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

The following reaction is at equilibrium at a pressure of 1 atm, in a closed container. NaOH(s) + CO₂(g) ⇄ NaHCO₃(s) ΔH°_rxn < 0 Which, if any, of the following actions will decrease the concentration of CO₂ gas present at equilibrium?

Correct Answer
verified

At 450°C, tert-butyl alcohol decomposes into water and isobutene. (CH₃) ₃COH(g) ⇄ (CH₃) ₂CCH₂(g) + H₂O(g) A reaction vessel contains these compounds at equilibrium. What will happen if the volume of the container is reduced by 50% at constant temperature?

Correct Answer
verified

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) ?

Correct Answer
verified

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.

Correct Answer
verified

Compounds A, B, and C react according to the following equation. 3A(g) + 2B(g) ⇄ 2C(g) At 100°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 K_c for this reaction?

Correct Answer
verified

For some gas-phase reactions, K_p = K_c.

Correct Answer
verified

Correct Answer
verified