Deck 13: Equilibrium

Question 1

Which is the correct equilibrium constant expression for the following reaction? 2C₆H₆(g) + 15O₂(g) 12CO₂(g) + 6H₂O(g)

A)
B)
C)
D)
E)

Answer 1

Question 2

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?

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

Answer 2

The reverse reaction will proceed in order to reestablish equilibrium.

Question 3

Write the equilibrium constant expression for the reaction shown.

A)
B)
C)
D)
E)

Answer 3

Question 4

The reaction system POBr₃(g) POBr(g) + Br₂(g) is at equilibrium.Which of the following statements describes the behavior of the system if POBr is added to the container?

A)POBr will be consumed in order to establish a new equilibrium.
B)The partial pressures of POBr₃ and POBr will remain steady while the partial pressure of bromine increases.
C)The partial pressure of bromine will increase while the partial pressure of POBr decreases.
D)The partial pressure of bromine remains steady while the partial pressures of POBr₃ and POBr increase.
E)The forward reaction will proceed to establish equilibrium.

Question 5

For the reaction 2X(g) + Y(g) 2Z(g), K = 1.00 ×10³ at 500 K.If at equilibrium the concentration of X is 0.20 M and the concentration of Y is 0.50 M, what is the equilibrium concentration of Z?

A)2.2 M
B)3.2 M
C)3.5 M
D)4.5 M
E)7.1 M

Question 6

What is defined as a fraction with equilibrium product concentrations in the numerator and equilibrium reactant concentrations in the denominator and each concentration raised to a power equal to the corresponding stoichiometric coefficient in the balanced chemical equation?

A)Reversibility expression
B)Reaction expression
C)Equilibrium expression
D)Product quotient
E)Mass action

Question 7

Write the equilibrium constant expression for the reaction shown. 2NOCl(g) ⇌ 2NO(g) + Cl₂(g)

A)
B)
C)
D)
E)

Question 8

At equilibrium, the rate of the forward reaction is equal to the rate of the reverse reaction.

Question 9

Hydrogen peroxide may decompose to form water and oxygen gas according to the following reaction. 2H₂O₂(g) 2H₂O(g) + O₂(g)
In a particular experiment, 1.75 moles of H₂O₂ were placed in a 2.5-L reaction chamber at 307ºC.After equilibrium was reached, 1.20 moles of H₂O₂ remained.What is K for the reaction?

A)2.0 × 10⁻⁴
B)2.3 × 10⁻²
C)2.4 × 10^-3
D)5.5 × 10⁻³
E)3.9 × 10⁻⁴

Question 10

At 35ºC, the equilibrium constant for the reaction 2NOCl(g) 2NO(g) + Cl₂(g) is K = 1.6 × 10⁻⁵.An equilibrium mixture was found to have the following concentrations of Cl₂ and NOCl: [Cl₂] = 1.2 × 10⁻² M; [NOCl] = 2.8 × 10⁻¹ M.Calculate the concentration of NO(g) at equilibrium.

A)1.0 × 10⁻⁴ M
B)1.0 × 10⁻² M
C)2.8 × 10⁻¹ M
D)2.4 × 10⁻² M
E)1.6 × 10⁻³ M

Question 11

A mixture of 0.500 mole of carbon monoxide and 0.400 mole of bromine was placed into a rigid 1.00-L container and the system was allowed to come to equilibrium.The equilibrium concentration of COBr₂ was 0.233 M.What is K for this reaction? CO(g) + Br₂(g) COBr₂(g)

A)5.23
B)2.14
C)1.17
D)0.467
E)0.191

Question 12

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 for this reaction?

A)0.309
B)0.601
C)1.66
D)2.25
E)3.24

Question 13

A container was charged with hydrogen, nitrogen, and ammonia gases at 120°C and the system was allowed to reach equilibrium.What will happen if the volume of the container is increased at constant temperature? 3H₂(g) + N₂(g) 2NH₃(g)

A)There will be no effect.
B)More ammonia will be produced at the expense of hydrogen and nitrogen.
C)Hydrogen and nitrogen will be produced at the expense of ammonia.
D)The equilibrium constant will increase.
E)The equilibrium constant will decrease.

Question 14

For the nitrogen fixation reaction, 3H₂(g) + N₂(g) 2NH₃(g), K = 6.0 × 10⁻² at 500°C.If 0.250 M H₂ and 0.050 M NH₃ are present at equilibrium, what is the equilibrium concentration of N₂?

A)3.3 M
B)2.7 M
C)0.20 M
D)0.083 M
E)0.058 M

Question 15

At elevated temperatures, hydrogen iodide may decompose to form hydrogen gas and iodine gas, as follows. 2HI(g) H₂(g) + I₂(g)
In a particular experiment, the concentrations at equilibrium were measured to be [HI] = 0.85 mol/L, [I₂] = 0.60 mol/L, and [H₂] = 0.27 mol/L.What is K for the above reaction?

A)5.3
B)0.22
C)4.5
D)0.19
E)1.6× 10²

Question 16

If, in a particular process, reactants are able to form products, and products are also able to form reactants, then this process may be described as

A)a reversible process.
B)an elementary process.
C)at equilibrium.
D)forbidden.
E)a forward process.

Question 17

During a chemical reaction, what defines when the concentrations of the reactants and products reach a constant level?

A)Elementary process
B)Reversible reaction
C)Rate law
D)Rate constant
E)Equilibrium

Question 18

A 6.0-L vessel was found to contain 1.0 mol BrCl3, 2.0 mol Br2 and 6.0 mol Cl2.What is the equilibrium constant, K, for this equilibrium mixture for the reaction 2BrCl3(g) Br2(g) + 3Cl2(g)?

A)0.014
B)108
C)18
D)12
E)432

Question 19

Which substances are included in the equilibrium constant expression, K_c?

A)Only pure solids
B)Only pure liquids
C)Only pure solids and liquids
D)Only gases and dissolved substances
E)All participating substances

Question 20

Which is the correct equilibrium constant expression for the following reaction? 2BrCl₃(g) Br₂(g) + 3Cl₂(g)

A) K_c = [Br₂] [Cl₂]/[BrCl₃]
B) K_c = [Br₂] [Cl₂]⁵/[BrCl₃]²
C) K_c = [Br₂] [Cl₂]³/[BrCl₃]²
D) K_c = [BrCl₃]²/([Br₂] × [Cl₂]3)
E) K_c = 2[BrCl₃]^₂/([Br²] × 3[Cl2]³)

Question 21

When the following reaction is at equilibrium 2NOCl(g) 2NO(g) + Cl₂(g)
then [NO]² [Cl₂] = K [NOCl]².

Question 22

Which reaction shown will have the highest concentration of products at equilibrium?

A)
B)
C)
D)
E)

Question 23

Determine the balanced chemical equation that corresponds to the given equilibrium expression.

A)
B)
C)
D)
E)

Question 24

If the system 3H₂(g) + N₂(g) 2NH₃(g) is at equilibrium and more N₂ is added, a net reaction that consumes some of the added N₂ will occur until a new equilibrium is reached.

Question 25

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

Question 26

Determine the balanced chemical equation that corresponds to the given equilibrium expression.

A)
B)
C)
D)
E)

Question 27

The equilibrium constant expression for the reaction CuO(s) + H₂(g) Cu(s) + H₂O(g) is K = [H₂]/[H₂O].

Question 28

Which reaction shown will have the highest concentration of reactants at equilibrium?

A)
B)
C)
D)
E)

Question 29

Which reaction shown will have the highest concentration of products at equilibrium?

A)
B)
C)
D)
E)

Question 30

Which reaction shown will have the highest concentration of reactants at equilibrium?

A)
B)
C)
D)
E)