Deck 14: Chemical Equilibrium-Equal but Opposite Reaction Rates

Question 1

Consider the equilibrium that exists between Fe²⁺ and Fe³⁺ ions in solution.The extra electron originally on one Fe²⁺ ion can be transferred to an Fe³⁺ ion.This amounts to no net reaction because iron(II)becomes iron(III)and iron(III)becomes iron(II).What is true about this equilibrium?

A)There is no activation energy for this reaction.
B)K = 1.
C)K = 0.
D)There is no net reaction,so there is no value for K.
E)The concentrations of iron(II)and iron(III)change because of the electron transfer.

Answer 1

K = 1.

Question 2

The equilibrium constant for the formation of hydrogen iodide from hydrogen and iodine is 45.0 at a certain temperature.H₂(g)+ I₂(s) $\leftrightarrows$ 2 HI(g)Which of the following is true regarding this equilibrium?
I.The reaction is product favored.
II.The reaction is reactant favored.
III.Equilibrium lies to the right.
IV.Equilibrium lies to the left.

A)I and III
B)I and IV
C)II and III
D)II and IV
E)None are true,as the concentrations of reactants and products are essentially the same.

Answer 2

I and III

Question 3

A chemical equilibrium 2 A $\leftrightarrows$ B has a forward rate constant,k_f = 10 M ^-1 s^-1,and a reverse rate constant,k_r = 5 s^-1.What is the value of the equilibrium constant for this system?

A)0.5
B)2
C)20
D)0.05
E)5

Answer 3

2

Question 4

A chemical equilibrium may be established by starting a reaction with __________

A)reactants only.
B)products only.
C)equal quantities of reactants and products.
D)any quantities of reactants and products.
E)all of the above

Question 5

The forward rate constant,k_f,and reverse rate constant,k_r,for a chemical reaction are not equal.Which of the following must be true?

A)The reaction will be unable to achieve equilibrium.
B)k_f and k_r will become equal as equilibrium is approached owing to concentration changes.
C)k_f and k_r will become equal as equilibrium is approached owing to temperature changes.
D)k_f and k_r will remain unequal,but the rates will become equal owing to concentration changes.
E)k_f and k_r will remain unequal,but the rates will become equal owing to temperature changes.

Question 6

For the equilibrium CO₂(g)+ N₂(g) $\leftrightarrows$ CO(g)+ N₂O(g),the forward and reverse rate constants at 1200 K are 9.1 $\times$ 10^-11 M ^-1 s^-1 and 1.5 $\times$ 10⁵ M ^-1 s^-1,respectively.What is the value of the equilibrium constant for CO(g)+ N₂O(g) $\leftrightarrows$ CO₂(g)+ N₂(g)?

A)1.6 $\times$ 10¹⁵
B)1.4 $\times$ 10^-5
C)6.1 $\times$ 10^-16
D)7.1 $\times$ 10⁴
E)1.0

Question 7

For an equilibrium reaction with K = 1.2 $\times$ 10⁸,the forward rate constant was found to be 3.5 $\times$ 10⁵.What is the value of the reverse rate constant?

A)3.5 $\times$ 10⁵
B)3.4 $\times$ 10²
C)4.2 $\times$ 10¹³
D)6.0 $\times$ 10^-5
E)2.9 $\times$ 10^-3

Question 8

A chemical equilibrium 2 A $\leftrightarrows$ B has a forward rate constant,k_f = 10 M ^-1 s^-1,and a reverse rate constant,k_r = 5 s^-1.If the system has a concentration of [A] = 0.10 M at equilibrium,what is the concentration of B at equilibrium?

A)20
B)2
C)0.2
D)0.02
E)200

Question 9

Which of the following is true for a chemical reaction at equilibrium?

A)only the forward reaction stops
B)only the reverse reaction stops
C)both the forward and reverse reactions stop
D)the rate constants for the forward and reverse reactions are equal
E)the rates of the forward and reverse reactions are equal

Question 10

For the equilibrium 2 HI(g) $\leftrightarrows$ H₂(g)+ I₂(g),the equilibrium constant at 700 K is approximately 1.75 $\times$ 10^-2,and the rate constant of the forward reaction is approximately 1.16 $\times$ 10^-3 M ^-1 s^-1.What is the value of the reverse rate constant?

A)6.63 $\times$ 10^-2 M ^-1 s^-1
B)1.51 $\times$ 10¹ M ^-1 s^-1
C)1.16 $\times$ 10^-3 M ^-1 s^-1
D)2.03 $\times$ 10^-5 M ^-1 s^-1
E)1.00 M ^-1 s^-1

Question 11

The law of mass action is a result of __________

A)the law of conservation of matter.
B)the law of conservation of energy.
C)kinetics of reversible reactions.
D)limiting reagent stoichiometry.
E)the third law of thermodynamics.

Question 12

Identify the equilibrium expression for the following reaction: CH₃CHO(g) $\leftrightarrows$ CH₄(g)+ CO(g).

A)
B)
C)
D)
E)

Question 13

For the equilibrium NO₂(g)+ O₂(g) $\leftrightarrows$ NO(g)+ O₃(g),the equilibrium constant at 300.0 K is approximately 2.9 $\times$ 10^-35,and the rate constant of the reverse reaction is approximately 8.5 $\times$ 10⁶ M ^-1 s^-1.What is the value of the forward rate constant?

A)2.1 $\times$ 10^-21 M ^-1 s^-1
B)3.4 $\times$ 10^-42 M ^-1 s^-1
C)2.5 $\times$ 10^-28 M ^-1 s^-1
D)4.1 $\times$ 10²⁷ M ^-1 s^-1
E)1.0 M ^-1 s^-1

Question 14

The equilibrium constant for the acid ionization of mercaptoethanol (HSCH₂CH₂OH )is 1.91 $\times$ 10^-10. HSCH₂CH₂OH(aq) $\leftrightarrows$ H⁺(aq)+ SCH₂CH₂OH^-(aq).Which of the following is true regarding this equilibrium?
I.The reaction is product favored.
II.The reaction is reactant favored.
III.Equilibrium lies far to the right.
IV.Equilibrium lies far to the left.

A)I and III
B)I and IV
C)II and III
D)II and IV
E)None are true,as the concentrations of reactants and products are comparable.

Question 15

Which of the following statements regarding the law of mass action and the mass action expression is NOT true?

A)The law of mass action defines the equilibrium constant to be the ratio of the forward and reverse rate constants for a particular equilibrium expression.
B)The law of mass action states that the ratio of product concentrations to reactant concentrations,raised to powers equal to their coefficients in a balanced chemical reaction,has a characteristic value at a given temperature.
C)The mass action expression is equivalent to the equilibrium expression in form but may be applied to reaction mixtures that are not at equilibrium.
D)At a given temperature,the characteristic ratio of products to reactants at equilibrium will be the same regardless of the composition of the starting mixture.
E)At a given temperature,the equilibrium concentrations of products and reactants depend on the composition of the starting mixture.

Question 16

Consider the equilibrium 2 NO(g) $\leftrightarrows$ N₂(g)+ O₂(g).At 1400 K,the equilibrium constant is approximately 2.6 $\times$ 10⁵.What is true about this equilibrium?

A)There is no activation energy for this reaction.
B)There is no net reaction,so there is no value for K.
C)K = 1.
D)k_f is greater than k_r at equilibrium.
E)The forward reaction rate is greater than the reverse reaction rate.

Question 17

Which of the following is/are equal once equilibrium is established?

A)the concentrations of reactant and products
B)the rates of the forward and reverse reactions
C)the time that a particular atom or molecule spends as a reactant and product
D)the rate constants of the forward and reverse reactions
E)all of the above are equal

Question 18

Which of the following statements regarding reaction rates and equilibrium is NOT true?

A)For a reaction to attain equilibrium,reactants and products must remain in contact with each other.
B)The rate of the forward reaction is at its maximum when the reactants are first mixed.
C)The rate of the reverse reaction is at its maximum when the reactants are first mixed.
D)The rate of the forward reaction decreases as the system approaches equilibrium.
E)The rate of the reverse reaction increases as the system approaches equilibrium.

Question 19

Which of the following statements regarding the equilibrium constant is NOT true?

A)When K >> 1,the concentration of products is much greater than the concentrations of reactants at equilibrium.
B)When K << 1,the concentration of reactants is much greater than the concentrations of products at equilibrium.
C)When K = 1,the concentration of products and reactants at equilibrium are equal.
D)When K = 1,the forward and reverse rate constants are equal.
E)When K >> 1,the products and reactants come to equilibrium rapidly.

Question 20

Which of the following is true for a chemical reaction at equilibrium regarding the concentration of products?

A)They will not change because there are no more reactants.
B)They will not change because the limiting reagent is gone.
C)They will not change because this is a constant for each reaction.
D)They will not change because the forward and reverse rates are equal.
E)They will change continually because of reversibility.

Question 21

Consider the following equilibrium: CH₄(g)+ H₂O(g) $\leftrightarrows$ CO(g)+ 3 H₂(g).When 1.00 M CH₄ and 1.00 M H₂O are placed in a reaction vessel at 1400.0 K,their equilibrium concentrations are 0.530 M.Calculate K_p at 1400 K.

A)4.69
B)3.55 $\times$ 10^-4
C)6.19 $\times$ 10⁴
D)539
E)0.0408

Question 22

Consider the following equilibrium: CH₄(g)+ 2 H₂S(g) $\leftrightarrows$ CS₂(g)+ 4 H₂(g).If K_p = 33.0 at 1400.0 K,calculate K_c.

A)3.79 $\times$ 10³
B)2.50 $\times$ 10^-3
C)0.287
D)4.36 $\times$ 10⁵
E)3.48

Question 23

An increase in the number of moles of gas as the reaction goes from reactants to products in a gas-phase equilibrium results in __________

A)K_p > K_c.
B)K_p < K_c.
C)K_p = K_c.
D)K_p + K_c = (RT) ^{$\Delta$ n}.
E)K_pK_c = (RT) ^{$\Delta$ n}.

Question 24

For the chemical equilibrium aA + bB $\leftrightarrows$ cC,the value of the equilibrium constant K is 10.What is the value of the equilibrium constant for the reaction cC $\leftrightarrows$ aA + bB?

A)0.1
B)10
C)1
D)100
E)-10

Question 25

For the equilibrium,2 PH₃(g) $\leftrightarrows$ P₂(g)+ 3 H₂(g),the equilibrium partial pressures are = 0.022 atm, = 0.289 atm,and = 0.867 atm at 873 K.Calculate K_p.

A)0.0585
B)17.1
C)0.0441
D)2.50 $\times$ 10^-3
E)389

Question 26

The equilibrium constant for the formation of calcium carbonate from the ions in solution is 2.2 $\times$ 10⁸ according to the reaction Ca²⁺(aq)+ CO₃^2-(aq) $\leftrightarrows$ CaCO₃(s).What is the value of the equilibrium constant for the reverse of this reaction?

A)the same,2.2 $\times$ 10⁸
B)-2.2 $\times$ 10⁸
C)2.2 $\times$ 10^-8
D)4.5 $\times$ 10^-9
E)4.5 $\times$ 10⁹

Question 27

Write the equilibrium expression for the following reaction: CH₄(g)+ 2 H₂S(g) $\leftrightarrows$ CS₂(g)+ 4 H₂(g).

A)
B)
C)
D)
E)

Question 28

For the chemical equilibrium aA + bB $\leftrightarrows$ cC,the value of the equilibrium constant K is 10.What is the value of the equilibrium constant for the reaction 2aA + 2 bB $\leftrightarrows$ 2cC?

A)10
B)20
C)40
D)100
E)400

Question 29

Consider the equilibrium,2 NOCl(g) $\leftrightarrows$ Cl₂(g)+ 2 NO(g).When 2.000 atm NOCl is placed in a tank at 500.0 K and allowed to come to equilibrium,the equilibrium partial pressure of Cl₂ is 0.226 atm.Calculate K_p.

A)0.0115
B)15.2
C)0.0193
D)0.0660
E)52.0

Question 30

Which of the following statements regarding the equilibrium constant and its units is true?

A)K is unitless because the concentrations or partial pressures in the expression are theoretically ratios of concentration or partial pressure to an ideal value of 1.000 M or 1.000 atm.
B)K is unitless because the units of the concentrations or partial pressures in the expression are dropped for convenience.
C)K is unitless because the units of the concentrations or partial pressures in the expression cancel if the equilibrium expression is written correctly.
D)K has units that reflect the units of the concentrations or partial pressures in the K expression.
E)K has units of M or atm depending on whether solutions or gases are involved.

Question 31

For the equilibrium,CH₄(g)+ 2 H₂S(g) $\leftrightarrows$ CS₂(g)+ 4 H₂(g),the concentrations at equilibrium are [CH₄] = 0.3322 M,[H₂S] = 0.6644 M,[CS₂] = 0.0678 M,and [H₂] = 0.2712 M at 1400.0 K.Calculate K _c.

A)0.167
B)2.50 $\times$ 10^-3
C)4.00 $\times$ 10²
D)6.00
E)0.694

Question 32

Write the equilibrium expression for the reaction: Zn²⁺(aq)+ 4 NH₃(aq) $\leftrightarrows$ Zn(NH₃)₄²⁺(aq).

A)
B)
C)
D)
E)

Question 33

Consider the equilibrium A + B $\leftrightarrows$ C.What is significant about the equilibrium state in which [B] = [C]?

A)[A] = K
B)[A] = [B] = [C]
C)[B] = [C] = K
D)[A] = 1/K
E)[C]/[B] = K

Question 34

Consider the following equilibrium: CO(g)+ 3 H₂(g) $\leftrightarrows$ CH₄(g)+ H₂O(g).If K_p = 1.61 $\times$ 10^-5 at 1400.0 K,calculate K_c.

A)1.40 $\times$ 10^-7
B)1.85 $\times$ 10^-3
C)541
D)0.212
E)1.22 $\times$ 10^-9

Question 35

Identify the equilibrium expression for the following reaction: 2 NO(g) $\leftrightarrows$ N₂(g)+ O₂(g).

A)
B)
C)
D)
E)

Question 36

For the following hypothetical equilibrium,A + 2 B $\leftrightarrows$ C,what is the value of the equilibrium constant if the concentrations at equilibrium are [A] = 4.5 * 10^-5 M,[B] = 2.2 *10^-2 M,and [C] = 9.4 * 10^-3 M?

A)0.22
B)9.9
C)4.3 * 10⁵
D)2.3 * 10⁸
E)9.5 * 10³

Question 37

Under what conditions are the values of K_c and K_p for a given gas-phase equilibrium the same?

A)there is no change in the moles of gas in the reaction
B)there is no change in the temperature during the reaction
C)the coefficients of the reactants and products are the same
D)the pressure remains constant
E)either K_c or K_p = 1

Question 38

Consider the equilibrium,Cl₂(g)+ 2 NO(g) $\leftrightarrows$ 2 NOCl(g).When 2.000 M NOCl is placed in a tank at 500.0 K and allowed to come to equilibrium,the equilibrium concentration of Cl₂ is 0.979 M.Calculate K_c.

A)45.6
B)15.2
C)0.938
D)2130
E)4.70 $\times$ 10^-4

Question 39

For the chemical equilibrium aA + bB $\leftrightarrows$ cC,the value of the equilibrium constant K is 10.What is the value of the equilibrium constant for the reaction 2cC $\leftrightarrows$ 2aA + 2bB?

A)0.1
B)0.2
C)0.01
D)20
E)10

Question 40

Consider the following equilibrium: ClF₃(g) $\leftrightarrows$ ClF(g)+ F₂(g).When 0.500 atm ClF₃ is placed in a reaction vessel at 700.0 K,its equilibrium partial pressure is 0.296 atm.Calculate K_c at 700.0 K.

A)408
B)0.123
C)0.429
D)0.141
E)2.45 $\times$ 10^-3

Question 41

Two students measure the equilibrium constant for the same chemical reaction.One student finds K_c to be 130; the other calculates K_c to be 11.4.The instructor checks their results and says they are both correct.Which of the following is a plausible explanation?

A)The values vary according to the way the measurement is made.One student must have measured product concentrations,while the second measured reactant concentrations.
B)The values vary according to the starting conditions of the reaction prior to equilibrium.One student must have started with all reactants,while the second must have started with all products.
C)The values vary according to the stoichiometric coefficients that are used.The balancing coefficients that the first student used must have been twice those that the second used.
D)The values vary according to direction of the reaction.One student must have used the reverse reaction.
E)The instructor must have made a mistake,as the equilibrium constant for a reaction must always be the same.

Question 42

There are many reactions involving nitrogen,oxygen,and nitrogen oxides at high temperatures.At 1000.0 K,the following reactions have the given equilibrium constants: N₂O₄(g) $\leftrightarrows$ 2 NO₂(g)K₁ = 1.5 $\times$ 10⁶ N₂(g)+ O₂(g) $\leftrightarrows$ NO₂(g)K₂ = 1.2 $\times$ 10^-5
Calculate the theoretical value of the equilibrium constant for N₂(g)+ 2 O₂(g) $\leftrightarrows$ N₂O₄(g).

A)9.6 $\times$ 10^-17
B)1.6 $\times$ 10^-11
C)6.7 $\times$ 10^-7
D)1.0 $\times$ 10¹⁶
E)36

Question 43

A series of four equilibrium steps can be defined for the following overall reaction that occurs in aqueous solution:
Cu²⁺ + 4 NH₃ $\leftrightarrows$ [Cu(NH₃)₄]²⁺ $\quad$ $\quad$ K_overall
Cu²⁺ + NH₃ $\leftrightarrows$ [Cu(NH₃)]²⁺ $\quad$ $\quad$ $\quad$ K₁
[Cu(NH₃)]²⁺ + NH₃ $\leftrightarrows$ [Cu(NH₃)₂]²⁺ $\quad$ K₂
etc.
What is true about K₄?

A)K₄ = K_overall
B)
C)
D)K₄ = K₁K₂K₃
E)

Question 44

For the equilibrium 2 PH₃(g) $\leftrightarrows$ P₂(g)+ 3 H₂(g),K_c = 0.0776 at 873 K.What is K_p at 873 K for the equilibrium P₂(g)+ H₂(g) $\leftrightarrows$ PH₃(g)?

A)7.36
B)0.136
C)2.34
D)0.182
E)40.4

Question 45

Chromic acid is a diprotic acid: H₂CrO₄(aq) $\leftrightarrows$ HCrO₄^-(aq)+ H⁺(aq)K_a1 = 3.55
HCrO₄^-(aq) $\leftrightarrows$ CrO₄^2-(aq)+ H⁺(aq)K_a2 = 3.36 $\times$ 10^-7
Calculate the theoretical value of the equilibrium constant for 2 HCrO₄^-(aq) $\leftrightarrows$ H₂CrO₄(aq)+ CrO₄^2-(aq).

A)1.05 $\times$ 10⁷
B)1.19 $\times$ 10^-6
C)9.46 $\times$ 10^-8
D)8.38 $\times$ 10⁵
E)0.282

Question 46

Which of the following statements regarding the mass action expression and the equilibrium constant expression is NOT true?

A)The mass action expression is usually applied to systems that have not attained equilibrium.
B)The mass action expression and the equilibrium constant expression have the same mathematical form.
C)The mass action expression never has the same value as the equilibrium constant expression.
D)There are infinitely many values for the mass action expression at a given temperature.
E)There is only one value of the equilibrium constant expression at a given temperature.

Question 47

Write the expression for the reaction quotient for the reaction,Ag⁺(aq)+ 2 NH₃(aq) $\leftrightarrows$ Ag(NH₃)₂⁺(aq)

A)
B)
C)
D)
E)

Question 48

For the equilibrium 2 HI(g) $\leftrightarrows$ H₂(g)+ I₂(g),K_p = 29.1 at 1000.0 K.What is K_c at 1000.0 K for the equilibrium H₂(g)+ H₂(g) $\leftrightarrows$ HI(g)?

A)0.0344
B)0.185
C)5.39
D)0.0172
E)0.0687

Question 49

If the reaction quotient Q has a larger value than the related equilibrium constant K,__________

A)the reaction is at equilibrium.
B)the reaction will continue to make more products.
C)the reaction will consume products and make reactants.
D)the reaction will release heat to achieve equilibrium.
E)the value of K will increase until it is equal to Q.

Question 50

A series of four equilibrium steps can be defined for the following overall reaction that occurs in aqueous solution:
Cu²⁺ + Cl ^- $\leftrightarrows$ [Cu(Cl)]⁺ $\quad$ $\quad$ $\quad$ K₁
…

[Cu(Cl)₃] ^- + Cl ^- $\leftrightarrows$ [Cu(Cl)₄]^{2 -} $\quad$ K₄
What is true about the equilibrium constant,K_c,for the reaction [Cu(Cl)₄]^{2 -} $\leftrightarrows$ Cu²⁺ + 4 Cl ^- ?

A)
B)
C)
D)
E)

Question 51

The equilibrium constants for the two reactions are known: M^m+ + 4 L^- $\leftrightarrows$ [ML₄]^m-4 K_f
HL $\leftrightarrows$ H⁺ + L^- K_a
What is the equilibrium constant,K_overall,for the reaction,M^m+ + 4 HL $\leftrightarrows$ [ML₄]^m-4 + 4 H⁺?

A)K_fK_a
B)K_f + 4K_a
C)K_f + K_a⁴
D)K_fK_a⁴
E)K_fK_a^1/4

Question 52

For the equilibrium H₂O(g)+ CH₄(g) $\leftrightarrows$ CO(g)+ 3 H₂(g),K_p = 1.61 $\times$ 10^-5 at 1400 K.At a given point,the partial pressures of the gases are = 0.264 atm, = 0.126 atm, = 0.0382 atm,and = 0.0974 atm.Which of the following statements is true?

A)Q < K so the reaction will continue to make more products.
B)Q > K so the reaction will consume products to make more reactants.
C)Q = K so the system is at equilibrium.
D)The value of K will decrease until it is equal to Q.
E)The value of K will increase until it is equal to Q.

Question 53

Consider the equilibrium A + B $\leftrightarrows$ C.What is significant about the reaction quotient when [B] = [C]?

A)only that [B] = [C]
B)[A] = [B] = [C]
C)[B] = [C] = K
D)[A] = K
E)The reaction must run in the forward direction.

Question 54

If the reaction quotient Q has a smaller value than the related equilibrium constant K,__________

A)the reaction is at equilibrium.
B)the reaction will continue to make more products.
C)the reaction will consume products and make reactants.
D)the reaction will release heat to achieve equilibrium.
E)the value of K will decrease until it is equal to Q.

Question 55

For the equilibrium 2 NOBr(g) $\leftrightarrows$ 2 NO(g)+ Br₂(g),K_c = 1.56 $\times$ 10^-3 at 300.0 K.What is K_p at 300.0 K for the equilibrium,NO(g)+ Br₂(g) $\leftrightarrows$ NOBr(g)?

A)5.10
B)126
C)1.58 $\times$ 10⁴
D)0.0384
E)26.0

Question 56

For the equilibrium 2 ClO(g) $\leftrightarrows$ Cl₂O₂(g),K_c = 4.96 $\times$ 10¹¹ at 253 K.What is K_c for the equilibrium Cl₂O₂(g) $\leftrightarrows$ ClO(g)?

A)7.04 $\times$ 10⁵
B)2.02 $\times$ 10^-12
C)9.90 $\times$ 10¹¹
D)1.01 $\times$ 10^-12
E)1.42 $\times$ 10^-6

Question 57

For the chemical equilibrium aA +bB $\leftrightarrows$ cC,the value of the equilibrium constant K is 10.0.What is the value of the equilibrium constant for the reaction cC $\leftrightarrows$ aA + bB?

A)0.316
B)10.0
C)3.16
D)0.200
E)31.6

Question 58

An equilibrium that strongly favors products has __________

A)a value of K <<1.
B)a value of K>>1.
C)a value of Q>>1.
D)a value of Q<<1.
E)K = Q.

Question 59

Cadmium and cyanide ions can form the complex ion,Cd(CN)₄^2-,in aqueous solutions.
Cd²⁺ + CN^- $\leftrightarrows$ [Cd(CN)]⁺ $\quad$ $\quad$ $\quad$$\quad$ K₁
…

[Cd(CN)₃] ^- + CN ^- $\leftrightarrows$ [Cd(CN)₄]^2- $\quad$ K₄
Cd²⁺ + 4 CN ^- $\leftrightarrows$ [Cd(CN)₄]^2- $\quad$ $\quad$ $\quad$ K_formation

The stepwise equilibrium constants are: K₁ = 1.5 *10⁵; K₂ = 2.6 * 10^4; K₃ = 2.1 * 10⁴; and,K₄ = 1.6 * 10³.
Hydrocyanic acid is a weak acid in water: HCN $\leftrightarrows$ H⁺ + CN^-,K_a = 6.2* 10 ^{- 10}.
What is the equilibrium constant,K_overall,for the reaction Cd²⁺ + 4 HCN $\leftrightarrows$ Cd(CN)₄^2- + 4 H⁺?

A)2.1 * 10^-2
B)8.1 * 10⁷
C)1.9 *0 10^-20
D)8.7 * 10⁵³
E)3.2 * 10⁸

Question 60

The following reactions at 1000.0 K have the following K_p values: H₂(g)+ Cl₂(g) $\leftrightarrows$ 2 HCl(g)K_p = 3.8 $\times$ 10⁴
H₂(g)+ Br₂(g) $\leftrightarrows$ 2 HBr(g)K_p = 5.1 $\times$ 10⁸
Br₂(g)+ Cl₂(g) $\leftrightarrows$ 2 BrCl(g)K_p = 0.20
What is K_p for the reaction,HCl(g)+ HBr(g) $\leftrightarrows$ BrCl(g)+ H₂(g),at 1000.0 K?

A)5.1 $\times$ 10^-7
B)1.0 $\times$ 10^-7
C)5.2 $\times$ 10^-15
D)0.45
E)1.0 $\times$ 10^-14

Question 61

Addition of reactants to a chemical reaction in solution or gas phase at equilibrium results in __________

A)an increase in K and a shift in equilibrium to produce more products.
B)an increase in K and a shift in equilibrium to produce more reactants.
C)a decrease in K and a shift in equilibrium to produce more products.
D)a decrease in K and a shift in equilibrium to produce more reactants.
E)no change in K and a shift in equilibrium to produce more products.

Question 62

In equilibrium expressions,the concentrations of pure solids and liquids __________

A)have the assigned value of one.
B)have the assigned value of zero.
C)have constant values,c_s and c₁.
D)are determined from the density and molar mass.
E)are treated as any other solute.

Question 63

If the temperature of an endothermic reaction at equilibrium could be increased instantaneously,what would be the instantaneous effect on Q and K before equilibrium was again achieved?

A)Q would increase and K would stay the same.
B)Q would decrease and K would stay the same.
C)Q would stay the same and K would increase.
D)Q would stay the same and K would decrease.
E)Both Q and K would stay the same.

Question 64

For the equilibrium 2 NOBr(g) $\leftrightarrows$ 2 NO(g)+ Br₂(g),K_c = 1.56 $\times$ 10^-3 at 300 K.Suppose 0.400 M NOBr is placed in a reaction vessel at 300 K.At a given point,the concentration of Br₂ is 0.0134 M.Which of the following statements is true?

A)Q < K so the reaction will continue to make more products.
B)Q > K so the reaction will consume products to make more reactants.
C)Q = K so the system is at equilibrium.
D)The value of K will decrease until it is equal to Q.
E)The value of K will increase until it is equal to Q.

Question 65

For the equilibrium N₂(g)+ O₂(g) $\leftrightarrows$ 2 NO(g),K_p = 0.0017 at 2300 K.At a given point,the partial pressures of the gases are = = 0.660 atm and = 0.0272 atm.Which of the following statements is true?

A)Q < K so the reaction will continue to make more products.
B)Q > K so the reaction will consume products to make more reactants.
C)Q = K so the system is at equilibrium.
D)The value of K will decrease until it is equal to Q.
E)The value of K will increase until it is equal to Q.

Question 66

Which of the following is true regarding the effect of a catalyst on chemical equilibrium?

A)Only the forward rate increases so the quantity of products increases.
B)Only the forward rate increases,but the quantity of products remains the same.
C)Both the forward and reverse rates increase and the quantity of products increases.
D)Both the forward and reverse rates increase,but the quantity of products is unchanged.
E)The effect varies depending on whether the reaction is endothermic or exothermic.

Question 67

Which of A through D is NOT a perturbation or stress to the equilibrium position of an endothermic chemical reaction that involves one or more gases?

A)adding reactants to a gas or solution reaction
B)removing products from a gas or solution reaction
C)decreasing the temperature
D)increasing pressure by adding an inert gas to a reaction in the gas phase
E)All of the above are perturbations to chemical equilibrium.

Question 68

What happens to the equilibrium between NO₂(g)and N₂O₄(g)in inert argon when the volume is increased and additional argon is added to maintain a constant total pressure?

A)The ratio of NO₂ to N₂O₄ increases solely because of the increase in volume.
B)The ratio of NO₂ to N₂O₄ increases solely because of the addition of argon.
C)The ratio of NO₂ to N₂O₄ decreases solely because of the increase in volume.
D)The ratio of NO₂ to N₂O₄ decreases solely because of the addition of argon.
E)The ratio of NO₂ to N₂O₄ remains the same,as the effects of the two processes cancel.

Question 69

For the equilibrium H₂(g)+ S(s) $\leftrightarrows$ H₂S(g),K_c = 6.1 $\times$ 10⁵ at 298 K.If the concentrations of H₂ and H₂S are equal,which of the following statements is true?

A)The concentration of S equals K_c.
B)The equilibrium constant equals 1.
C)The reaction quotient equals 1.
D)The system is at equilibrium.
E)The concentrations of H₂ and H₂S can never be equal.

Question 70

Consider the equilibrium CH₄(g)+ H₂O(g)+ 206 kJ $\leftrightarrows$ CO(g)+ 3 H₂(g).Which of the following disturbances will NOT cause the system to shift to the right to reestablish equilibrium?

A)The partial pressure of CH₄ increases.
B)The partial pressure of CO decreases.
C)The volume decreases.
D)The temperature increases.
E)All of these will cause the system to shift to the right.

Question 71

Which of the following is the equilibrium expression for the oxidation of copper? 2 Cu(s)+ O₂(g) $\leftrightarrows$ 2 CuO(s)

A)
B)
C)
D)
E)

Question 72

Cylinders of NO gas may contain small quantities of oxygen as impurities,leading to the formation of NO₂ in equilibrium with the NO and oxygen.Is this contamination by NO₂ dependent on pressure in the tank?

A)Yes,there will be more NO₂ at higher pressures.
B)Yes,there will be less NO₂ at higher pressures.
C)No,the amount of NO₂ has nothing to do with pressure.
D)No,the amount of NO₂ depends on the partial pressure,not the total pressure.
E)There is no way to tell without additional information.

Question 73

In a simple equilibrium A + B $\leftrightarrows$ C,will there be any stress to the system if both B and C were added to the equilibrium system simultaneously and in the same amount?

A)No,these two stresses will always cancel each other out.
B)No,these two stresses will cancel each other out unless the initial concentrations of B and C are also the same.
C)Yes,the same amount of A is also required for the stresses to cancel.
D)Yes,unless the initial concentrations of B and C are also the same.
E)More than two of the above statements are correct.

Question 74

Naphthalene undergoes sublimation: C₁₀H₈(s) $\leftrightarrows$ C₁₀H₈(g).In a closed container at 300.0 K,the equilibrium vapor pressure is 0.10 torr.What are the values of K_p and K_c?

A)K_p = 0.10; K_c = 4.1 $\times$ 10^-3
B)K_p = 1.3 $\times$ 10^-4; K_c = 1.3 $\times$ 10^-4
C)K_p = 1.3 $\times$ 10^-4; K_c = 3.2 $\times$ 10^-3
D)K_p = 1.3 $\times$ 10^-4; K_c = 5.3 $\times$ 10^-6
E)More information is required.

Question 75

Which of the following occurs when reactants are added to a chemical reaction in solution or the gas phase at equilibrium?

A)Q increases and the equilibrium shifts to produce more products.
B)Q increases and the equilibrium shifts to produce more reactants.
C)Q decreases and the equilibrium shifts to produce more products.
D)Q decreases and the equilibrium shifts to produce more reactants.
E)Q is unchanged by the addition of reactants.

Question 76

Increasing the temperature of an exothermic reaction results in __________

A)more products and fewer reactants.
B)more reactants and fewer products.
C)more reactants and products.
D)fewer reactants and products.
E)no change in the quantities of reactants and products.

Question 77

For the equilibrium (CH₃)₃CCl(g) $\leftrightarrows$ (CH₃)₂C = CH₂(g)+ HCl(g),K_p = 3.45 at 500 K.At a given point,the partial pressures of the gases are = 0.810 atm and = 0.190 atm.Which of the following statements is true?

A)Q < K so the reaction will continue to make more products.
B)Q > K so the reaction will consume products to make more reactants.
C)Q = K so the system is at equilibrium.
D)The value of K will decrease until it is equal to Q.
E)The value of K will increase until it is equal to Q.

Question 78

For a chemical reaction at equilibrium,which of the following will change the value of the equilibrium constant K?
(I)Changing the temperature
(II)Changing the total concentration of reactants and products
(III)Changing the reaction coefficients

A)I only
B)II only
C)III only
D)I and II only
E)I and III only

Question 79

Which of the following is the equilibrium expression for the scrubbing reaction of calcium oxide and sulfur dioxide to make calcium sulfite? CaO(s)+ SO₂(g) $\leftrightarrows$ CaSO₃(s)

A)K_c = [SO₂]
B)
C)K_c = [CaO] + [SO₂]
D)K_c = [CaSO₃] - [CaO] - [SO₂]
E)

Question 80

Which of the following occurs when products are removed from a chemical reaction in solution or the gas phase at equilibrium?

A)Q increases and the equilibrium shifts to produce more products.
B)Q increases and the equilibrium shifts to produce more reactants.
C)Q decreases and the equilibrium shifts to produce more products.
D)Q decreases and the equilibrium shifts to produce more reactants.
E)Q is unchanged by the addition of reactants.