Deck 12: Gaseous Chemical Equilibrium

Question 1

Use the equilibrium constants for the following reactions at 700°C 2SO₂(g)+ O₂(g) 2SO₃(g)
K₁ = 4.8
2NO(g)+ O₂(g) 2NO₂(g)
K₂ = 16
To determine the equilibrium constant for the following reaction.
SO₃(g)+ NO(g) SO₂(g)+ NO₂(g)

A) 0.30
B) 0.55
C) 0.85
D) 1.8
E) 3.3

Answer 1

1.8

Question 2

What is the correct equilibrium constant expression for the following reaction? C₄H₁₀(g)+ O₂(g) 4CO₂(g)+ 5H₂O(g)

A)
B)
C)
D)
E)

Answer 2

Question 3

What is the relationship between K_p and K_c for the reaction below? N₂(g)+ 3 H₂(g) 2 NH₃(g)

A)
B)
C)
D)
E)

Answer 3

Question 4

For the following reaction, 2SO₃(g) 2SO₂(g)+ O₂(g)
The equilibrium constant,K,is 1.32 at 627°C.What is the equilibrium constant,at 627°C,for the reaction below?
SO₂(g)+ 1/2O₂(g) SO₃(g)

A) -1.15
B) -0.66
C) 0.379
D) 0.870
E) 1.52

Question 5

Write the balanced chemical reaction which corresponds to the following equilibrium constant expression.

A) 4N₂O₅(g) O₂(g)+ 2NO₂(g)
B) 2N₂O₅(g) O₂(g)+ 4NO₂(g)
C) N₂O₅(g) O₂(g)+ NO₂(g)
D) O₂(g)+ 2NO₂(g) 4N₂O₅(g)
E) O₂(g)+ 4NO₂(g) 2N₂O₅(g)

Question 6

The reaction below was studied at a high temperature.At equilibrium,the partial pressures of the gases are as follows: PCl₅ = 1.4 × 10−⁴ atm,PCl₃ = 2.4 × 10−² atm,Cl₂ = 3.0 × 10−¹ atm.What is the value of K for the reaction? PCl₅(g) PCl₃(g)+ Cl₂(g)

A) 4.3 × 10−⁴
B) 0.019
C) 0.32
D) 51
E) 2.3 × 10³

Question 7

What is the correct equilibrium constant expression for the formation of ammonia gas from nitrogen gas and hydrogen gas?

A) $K=\frac{P_{\mathrm{NH}_{3}}}{P_{\mathrm{N}_{2}} \times P_{\mathrm{H}_{2}}}$
B) $K=\frac{\left(2 P_{\mathrm{NH}_{3}}\right)^{2}}{P_{\mathrm{N}_{2}} \times\left(3 P_{\mathrm{H}_{2}}\right)^{3}}$
C) $K=\frac{P_{\mathrm{N}_{2}} \times\left(3 P_{\mathrm{H}_{2}}\right)}{\left(2 P_{\mathrm{NH}_{3}}\right)}$
D) $K=\frac{\left(P_{\mathrm{NH}_{3}}\right)^{2}}{P_{\mathrm{N}_{2}} \times\left(P_{\mathrm{H}_{2}}\right)^{3}}$
E) $K=\frac{P_{\mathrm{N}_{2}} \times\left(P_{\mathrm{H}_{2}}\right)^{3}}{\left(P_{\mathrm{NH}_{3}}\right)^{2}}$

Question 8

Write a balanced chemical equation which corresponds to the following equilibrium constant expression.

A) 1/2N₂(g)+ 3/2H₂(g) NH₃(g)
B) N₂(g)+ 3 H₂(g) 2NH₃(g)
C) 2NH₃(g) N₂(g)+ 3H₂(g)
D) NH₃(g) 1/2N₂(g)+ 3/2H₂(g)
E) 2N₂(g)+ 6H₂(g) 4NH₃(g)

Question 9

For which of the following reactions does K_c equal K_p?

A) Sn(s)+ 2H₂O(g) SnO₂(s)+ 2H₂(g)
B) 2C₂H₆(g)+ 7O₂(g) 4CO₂(g)+ 6H₂O(g)
C) NH₄Cl(s) NH₃(g)+ HCl(g)
D) N₂(g)+ 3H₂(g) 2NH₃(g)
E) CaCO₃(s) CaO(s)+ CO₂(g)

Question 10

Use the equilibrium constants for the following reactions 2NO(g) N₂(g)+ O₂(g)
K₁ = 2.4 × 10³⁰
2NO(g)+ O₂(g) 2NO₂(g)
K₂ = 2.4 × 10¹²
To determine the equilibrium constant for the reaction below.
N₂(g)+ 2O₂(g) 2NO₂(g)

A) 1.7 × 10−⁴³
B) 1.0 × 10−¹⁸
C) 5.8 × 10¹⁸
D) 2.4 × 10³⁰
E) 5.8 × 10⁴²

Question 11

What is the correct equilibrium constant expression for the following reaction? H₂(g)+ I₂(s) 2HI(g)

A)
B)
C)
D)
E)

Question 12

Given the following equilibrium equations, 2N₂O(g) 2N₂(g)+ O₂(g)
K₁ = 8.3 × 10³⁴
N₂O₄(g) 2NO₂(g)
K₂ = 4.6 × 10−³
2NO₂(g) N₂(g)+ 2O₂(g)
K₃ = 5.9 × 10¹⁶
Calculate K for the decomposition of dinitrogen tetraoxide to nitrogen dioxide and oxygen.
2N₂O₄(g) 2N₂O(g)+ 3O₂(g)
K₄ = ?

A) 1.1 × 10−⁴¹
B) 1.3 × 10−²⁰
C) 8.9 × 10−⁷
D) 3.3 × 10²¹
E) 2.3 × 10⁴⁹

Question 13

For the reaction below,the partial pressures of gases at equilibrium are as follows: H₂ = 7.1 × 10−⁵ atm,Cl₂ = 2.5 × 10−⁶ atm,and HCl = 3.0 atm.What is the value of the equilibrium constant,K? H₂(g)+ Cl₂(g) 2HCl(g)

A) 2.0 × 10−¹¹
B) 5.9 × 10−¹¹
C) 1.6 × 10−⁹
D) 1.7 × 10¹⁰
E) 5.1 × 10¹⁰

Question 14

What is the correct equilibrium constant expression for the following reaction? MgCO₃(s) MgO(s)+ CO₂(g)

A)
B)
C)
D)
E)

Question 15

Given the following chemical equilibria, $\begin{array}{l}\begin{array}{lll}\mathrm{N}_{2}(g)+\mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{NO}(g) \\\mathrm{N}_{2}(g)+3 \mathrm{H}_{2}(g) \rightleftharpoons 2 \mathrm{NH}_{3}(g) \\\mathrm{H}_{2}(g)+1 / 2 \mathrm{O}_{2}(g) \rightleftharpoons \mathrm{H}_{2} \mathrm{O}(g)\end{array}\begin{array}{lll}K_{1} \\K_{2} \\K_{3} \\\end{array}\end{array}$

Determine the method used to calculate the equilibrium constant for the reaction below.
$4 \mathrm{NH}_{3}(\mathrm{~g})+5 \mathrm{O}_{2}(\mathrm{~g}) \rightleftharpoons 4 \mathrm{NO}(\mathrm{g})+6 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$ $\quad$$\quad$$\quad$ $K_{\mathrm{c}}$

A) $K_{\mathrm{c}}=K_{1} \times K_{2} \times K_{3}$
B) $K_{c}=\frac{K_{1}^{2} \times K_{3}^{6}}{K_{2}^{2}}$
C) $K_{\mathrm{c}}=2 K_{1}-2 K_{2}+3 K_{3}$
D) $K_{\mathrm{c}}=\frac{6\left(K_{1} \times K_{3}\right)}{2 K_{2}}$
E) $K_{\mathrm{c}}=\frac{K_{1}^{2} \times K_{2}^{2}}{K_{3}^{3}}$

Question 16

Which of the following reactions is a homogeneous equilibrium expression?

A) CaCO₃(s) CaO(s)+ CO₂(g)
B) NH₃(g)+ HCl(g) NH₄Cl(s)
C) Mg(s)+ Cl₂(g) MgCl₂(s)
D) FeO(s)+ CO(g) Fe(s)+ CO₂(g)
E) 2NO(g)+ O₂(g) 2NO₂(g)

Question 17

What is the correct equilibrium constant expression for the following reaction? CO₂(g)+ 2H₂O(g) CH₄(g)+ 2O₂(g)

A)
B)
C)
D)
E) none of the above

Question 18

Which of the following reactions is a heterogeneous equilibrium expression?

A) 2NO(g)+ O₂(g) 2NO₂(g)
B) 2NH₃(g) N₂(g)+ 3H₂(g)
C) 2H₂(g)+ O₂(g) 2H₂O(g)
D) 2S(s)+ 3O₂(g) 2SO₃(g)
E) C₂H₄(g)+ H₂(g) C₂H₆(g)

Question 19

At 25°C,the partial pressure of gases at equilibrium are as follows: N₂ = 0.12 atm,O₂ = 0.040 atm,and NO = 4.5 × 10−¹⁷ atm.What is the value of the equilibrium constant,K? N₂(g)+ O₂(g) 2NO(g)

A) 4.2 × 10−³¹
B) 5.2 × 10−²¹
C) 9.4 × 10−¹⁵
D) 1.1 × 10¹⁴
E) 2.4 × 10³⁰

Question 20

The value of the equilibrium constant for the following reaction is 345. A + 2B 3C + D
What is the value of the equilibrium constant for the reaction below?
2A + 4B 6C + 2D

A) K = 345
B) K = (345)² = 1.19 × 10⁵
C) K = (345)^1/2 = 18.6
D) K = (2 × 345)² = 4.76 × 10⁵
E) K = 2 × (345)² = 2.38 × 10⁵

Question 21

Nitrosyl bromide decomposes according to the chemical equation below. 2NOBr(g) 2NO(g)+ Br₂(g)
1)00 atm of NOBr is sealed in a flask.At equilibrium,the partial pressure of NOBr is 0.82 atm.What is the equilibrium constant for the reaction?

A) 3.6 × 10−³
B) 8.7 × 10−³
C) 2.8 × 10−²
D) 3.5 × 10−²
E) 4.3 × 10−³

Question 22

At 25°C,the decomposition of dinitrogen tetraoxide N₂O₄(g) 2NO₂(g)
Has an equilibrium constant (K)of 0.144.If the equilibrium pressure of nitrogen dioxide is 0.298 atm,what is the pressure of dinitrogen tetraoxide?

A) 0.0128 atm
B) 0.617 atm
C) 1.03 atm
D) 1.62 atm
E) 2.07 atm

Question 23

Assume that the following chemical reaction is at equilibrium. 2ICl(g) I₂(g)+ Cl₂(g)
ΔH° = +26.9 kJ
At 25°C,K = 2.0 × 10⁵.If the temperature is increase to 45°C,which statement applies?

A) K will decrease and the reaction will proceed in the backward direction.
B) K will decrease and the reaction will proceed in the forward direction.
C) K will remain unchanged and the reaction will proceed in the forward direction.
D) K will increase and the reaction will proceed in the backward direction.
E) K will increase and the reaction will proceed in the forward direction.

Question 24

For the following reaction,the equilibrium constant (K)equals 21.2. SnO₂(s)+ 2H₂(g) Sn(s)+ 2H₂O(g)
At equilibrium,the total pressure of the system is 0.390 atm.What is the partial pressure of each gas?

A) 0.0303 atm H₂;0.360 atm H₂O
B) 0.0522 atm H₂;0.339 atm H₂O
C) 0.0696 atm H₂;0.320 atm H₂O
D) 0.320 atm H₂;0.0696 atm H₂O
E) 0.339 atm H₂;0.0522 atm H₂O

Question 25

In which of the following equilibrium systems would an increase in volume (at constant temperature)cause the reaction to shift to the right?

A) N₂O₄(g) 2NO₂(g)
B) N₂(g)+ 3H₂(g) 2NH₃(g)
C) H₂(g)+ Cl₂(g) 2HCl(g)
D) Answers a and b are correct.
E) Answers b and c are correct.

Question 26

For the system CO(g)+ H₂O(g) CO₂(g)+ H₂(g)
K is 1.6 at 900 K.If 0.400 atm CO(g)and 0.400 atm H₂O(g)are combined in a sealed flask,what is the equilibrium partial pressure of CO₂(g)?

A) 0.22 atm
B) 0.31 atm
C) 0.47 atm
D) 0.51 atm
E) 0.65 atm

Question 27

In which of the following equilibrium systems will an increase in the pressure have no effect on the concentrations of products and reactants?

A) H₂(g)+ F₂(g) 2 HF(g)
B) N₂(g)+ 3 H₂(g) 2 NH₃(g)
C) CaCO₃(s) CaO(s)+ CO₂(g)
D) 2 NOBr(g) 2 NO(g)+ Br₂(g)
E) 2 H₂O(g)+ O₂(g) 2 H₂O₂(g)

Question 28

The equilibrium constant,K_p,for the reaction below is 0.24 at 1500°C. SO₃(g)+ NO(g) SO₂(g)+ NO₂(g)
If 0.30 atm of sulfur trioxide,0.15 atm of nitrogen monoxide,0.55 atm of sulfur dioxide,and 0.030 atm of nitrogen dioxide are mixed,what changes in pressure will occur?

A) The pressures of SO₃ and NO decrease;the pressures of SO₂ and NO₂ increase.
B) The pressures of SO₃ and NO increase;the pressures of SO₂ and NO₂ decrease.
C) The pressures of SO₃ and SO₂ decrease;the pressures of NO and NO₂ increase.
D) The pressures of SO₃ and SO₂ increase;the pressures of NO and NO₂ decrease.
E) Equal numbers of particles exist on both sides of the equation;no reaction will occur.

Question 29

At 25°C,the decomposition of dinitrogen tetraoxide N₂O₄(g) 2NO₂(g)
Has an equilibrium constant (K)of 0.144.At equilibrium,the total pressure of the system is 0.500 atm.What is the partial pressure of each gas?

A) N₂O₄ = 0.206 atm;NO₂ = 0.294 atm
B) N₂O₄ = 0.212 atm;NO₂ = 0.288 atm
C) N₂O₄ = 0.288 atm;NO₂ = 0.212 atm
D) N₂O₄ = 0.294 atm;NO₂ = 0.206 atm
E) N₂O₄ = 0.437 atm;NO₂ = 0.063 atm

Question 30

The equilibrium constant for a gas phase reaction is measured at two temperatures.At 100°C,the equilibrium constant is 36.At 200°C,the equilibrium constant is 147.Which of the following statements is correct for this equilibrium?

A) The reaction must be first-order.
B) The reaction is endothermic.
C) A catalyst must be present.
D) Each reactant molecule decomposes into two or more product molecules.
E) One of the products must be a solid.

Question 31

Hydrogen iodide can decompose into hydrogen and iodine gases. 2HI(g) H₂(g)+ I₂(g)
K for the reaction is 0.016.If 0.148 atm of HI(g)is sealed in a flask,what is the pressure of each gas when equilibrium is established?

A) HI = 0.118 atm;H₂ = 0.015 atm;I₂ = 0.015 atm
B) HI = 0.133 atm;H₂ = 0.015 atm;I₂ = 0.015 atm
C) HI = 0.110 atm;H₂ = 0.019 atm;I₂ = 0.019 atm
D) HI = 0.126 atm;H₂ = 0.022 atm;I₂ = 0.022 atm
E) HI = 0.174 atm;H₂ = 0.022 atm;I₂ = 0.022 atm

Question 32

The formation of ammonia from elemental nitrogen and hydrogen is an exothermic process. $\mathrm{N}_{2}(g)+3 \mathrm{H}_{2}(g) \rightleftharpoons 2 \mathrm{NH}_{3}(g) \quad\quad\quad\quad\quad\quad \Delta H^{\circ}=-92.2 \mathrm{~kJ} / \mathrm{mol}$
Assuming the reaction is at equilibrium,which one of the following changes will drive the reaction to the right?

A) adding ammonia
B) increasing the temperature
C) increasing the pressure
D) removing hydrogen
E) adding a catalyst

Question 33

Nitrosyl chloride decomposes according to the chemical equation below. 2NOCl(g) 2NO(g)+ Cl₂(g)
A pressure of 0.320 atm of nitrosyl chloride is sealed in a flask and allowed to reach equilibrium.If 22.6% of the NOCl decomposes,what is the equilibrium constant for the reaction?

A) 0.00153
B) 0.00308
C) 0.00611
D) 0.00730
E) 0.02471

Question 34

Hydrogen iodide can decompose into hydrogen and iodine gases. 2HI(g) H₂(g)+ I₂(g)
K_p for the reaction is 0.016.If 0.350 atm of HI(g)is sealed in a flask,what is the total pressure of the system when equilibrium is established?

A) 0.258 atm
B) 0.279 atm
C) 0.350 atm
D) 0.385 atm
E) 0.412 atm

Question 35

Nitrogen can react with oxygen to form nitrogen monoxide. N₂(g)+ O₂(g) 2NO(g)
K = 1.0 × 10−³⁰ at 25°C
When equilibrium is established,the partial pressures of nitrogen and oxygen are 1.2 atm and 3.1 atm,respectively.What is the equilibrium pressure of nitrogen monoxide?

A) 3.7 × 10−³⁰ atm
B) 1.9 × 10−¹⁵ atm
C) 2.7 × 10−¹³ atm
D) 1.9 × 10−¹⁰ atm
E) 3.7 × 10−⁷ atm

Question 36

At sufficiently high temperatures,ammonium iodide decomposes to ammonia and hydrogen iodide. NH₄I(s) NH₃(g)+ HI(g)
A mass of 5.00 g of NH₄I is sealed in a 2.00-L flask and heated to 673 K.If 2.56 g NH₄I(s)remain unreacted when the system has reached equilibrium,what is the equilibrium constant (K_p)for the reaction? (R = 0.0821 L⋅atm/mol⋅K)

A) 0.15
B) 0.22
C) 0.47
D) 0.59
E) 0.89

Question 37

At a given temperature,the equilibrium constant (K_p)for the decomposition of dinitrogen tetraoxide to nitrogen dioxide is 0.172.If 0.224 atm N₂O₄ is sealed in a flask,what partial pressure of NO₂ will exist at equilibrium? N₂O₄(g) 2NO₂(g)

A) 0.0385 atm
B) 0.158 atm
C) 0.196 atm
D) 0.257 atm
E) 0.379 atm

Question 38

For the reaction 2A 3B
K_c = 1.37.If the concentrations of A and B are equal,what is the value of that concentration?

A) 0.685 M
B) 0.822 M
C) 1.17 M
D) 1.37 M
E) 1.88 M

Question 39

Consider the following equilibrium: N₂(g)+ O₂(g) 2NO(g)
At a certain temperature the equilibrium constant for the reaction is 0.0255.What is the partial pressure of NO gas at equilibrium if the initial pressure of all the gases (both reactants and products)is 0.300 atm?

A) 6.65 × 10−²
B) 0.183
C) 0.234
D) 0.252
E) 0.417

Question 40

The reaction of nitrogen gas and oxygen gas to form nitrogen monoxide, N₂(g)+ O₂(g) 2NO(g)
Has an equilibrium constant of 1.0 × 10−³⁰ at 298 K.What equilibrium partial pressure of NO(g)will form if 0.50 atm of N₂ and 0.50 atm of O₂ are sealed in a flask at 298 K?

A) 1.0 × 10−⁶⁰ atm
B) 5.0 × 10−³¹ atm
C) 1.0 × 10−³⁰ atm
D) 1.0 × 10−¹⁵ atm
E) 5.0 × 10−¹⁶ atm

Question 41

"If a chemical system at equilibrium is disturbed by adding a gaseous species (reactant or product),the reaction will proceed in such a direction as to consume part of the added species" is a statement of

A) the ideal gas law.
B) Le Châtelier's principle.
C) the de Broglie equation.
D) the van't Hoff equation.
E) the first law of thermodynamics.

Question 42

Calcium carbonate decomposes to calcium oxide and carbon dioxide. CaCO₃(s) CaO(s)+ CO₂(g)
ΔH° = +179 kJ
The equilibrium constant for this reaction is 9.7 × 10−²⁴ at 298 K.What is the equilibrium constant at 575 K? (R = 8.31 J/mol⋅K)

A) 7.5 × 10−¹⁶
B) 1.3 × 10−⁸
C) 1.4 × 10³⁸
D) 1.3 × 10¹⁵
E) 1.0 × 10²³

Question 43

Consider the reaction A(g) 2B(g)where K_p = 4.1 at 25°C.If 0.75 atm A(g)and 1.5 atm B(g)are initially present in a 1.0 L flask at 25°C,what change in partial pressures (if any)will occur in time?

A) The partial pressure of A will decrease and the partial pressure of B will decrease.
B) The partial pressure of A will decrease and the partial pressure of B will increase.
C) The partial pressure of A will increase and the partial pressure of B will decrease.
D) The partial pressure of A will increase and the partial pressure of B will increase.
E) The partial pressures of both A and B will remain unchanged.

Question 44

The reaction of nitrogen with hydrogen to form ammonia is thermodynamically favorable. N₂(g)+ 3H₂(g) 2NH₃(g)
ΔH° = −92.2 kJ
The equilibrium constant for this reaction is 6.0 × 10⁵ at 298 K.At what temperature is the equilibrium constant equal to 1.0 × 10³? (R = 8.31 J/mol⋅K)

A) 85 K
B) 110 K
C) 310 K
D) 360 K
E) 2800 K

Question 45

If the value of Q is less than K_p,then

A) the system is in equilibrium.
B) a catalyst is necessary to achieve equilibrium.
C) the reaction will go left or right depending upon the reaction stoichiometry.
D) the reaction will proceed to the right until equilibrium is established.
E) the reaction will proceed to the left until equilibrium is established.

Question 46

A 2.5 L flask is filled with 0.25 atm SO₃,0.20 atm SO₂,and 0.40 atm O₂,and allowed to reach equilibrium.Assume the temperature of the mixture is chosen so that K_p = 0.12.Predict the effect on the partial pressure of SO₃ as equilibrium is achieved by using Q,the reaction quotient. 2 SO₃(g) 2 SO₂(g)+ O₂(g)

A) The partial pressure of SO₃ will decrease because Q > K.
B) The partial pressure of SO₃ will decrease because Q < K.
C) The partial pressure of SO₃ will increase because Q < K.
D) The partial pressure of SO₃ will increase because Q > K.
E) The partial pressure of SO₃ will remain the same because Q = K.

Question 47

The Haber process for the production of ammonia relies on high temperatures and pressures.Which of these,high temperatures or pressures,actually reduce the yield of the reaction at equilibrium? N₂(g)+ 3H₂(g) 2NH₃(g)
ΔH° = −92.2 kJ

A) High pressure
B) High temperature
C) Both
D) Neither
E) Can't be determined

Question 48

For the reaction C(s)+ CO₂(g) 2CO(g)
K_c = 168.A mixture contains some C(s),[CO] = 0.50 M and [CO₂] = 0.75 M.Therefore the system ____ at equilibrium,because ____.

A) is not;the value of Q is 0.67
B) is not;the value of Q is 1.5
C) is;the value of Q is 0.67
D) is not;the value of Q is 0.33
E) is;the value of Q is 0.33

Question 49

The Haber process for the production of ammonia relies on a heterogeneous catalyst.How does the use of this catalyst effect the yield of the reaction at equilibrium? $\mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NH}_{3}(\mathrm{~g}) \quad\quad\quad\quad\quad\quad \Delta H^{\circ}=-92.2 \mathrm{~kJ}$

A) Yield is increased
B) Yield is decreased
C) Depends on the catalyst used
D) Doesn't effect yield
E) Can't be determined