Question 1

A chemical equilibrium
2 A  ⇆\leftrightarrows⇆  B
Has a forward rate constant, kf = 10 M -1s-1, and a reverse rate constant, kr = 5.0 s-1. What is the value of the equilibrium constant for this system?

Accepted Answer

A)   0.5
B)   2.0
C)   20
D)   0.050
E)   5.0

Question 2

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

Accepted Answer

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 3

The equilibrium constants for the two reactions are known:  Mm++4 L−⇆[ML4]m−4KaHL⇆H++L−Kb\begin{array}{ll}\mathrm{M}^{\mathrm{m}+}+4 \mathrm{~L}^{-} \leftrightarrows\left[\mathrm{ML}_{4}ight]^{\mathrm{m}-4}&&&K_{a}\\mathrm{HL} \leftrightarrows \mathrm{H}^{+}+\mathrm{L}^{-}&&&K_{b}\\end{array}Mm++4 L−⇆[ML4​]m−4HL⇆H++L−​​​Ka​Kb​​  What must be the value of the equilibrium constant, Koverall for the following overall reaction?
Mm+ + 4HL  ⇆\leftrightarrows⇆ [ML4]m-4 + 4H+ Koverall

Accepted Answer

A)   KaKb
B)   Ka + 4Kb
C)   Ka + Kb4
D)   KaKb4
E)   KaKb1/4

Question 4

The sulfide ion, S2-, reacts with water as a weak base:
S2- + H2O  ⇆\leftrightarrows⇆  SH- + OH- K = 1.0
If sodium sulfide were dissolved in water to make a solution of 0.50 M, what would be the resulting concentration of OH-?

Accepted Answer

A)   0.50 M
B)   0.37 M
C)   0.63 M
D)   1.0 M
E)   0.19 M

Question 5

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

Accepted Answer

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 6

Increasing the temperature of an exothermic reaction results in ________

Accepted Answer

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 7

Water can decompose at an elevated temperature to give hydrogen and oxygen according to the equation below. At a particular temperature, the partial pressures of H2O, H2, and O2 are 0.055 atm, 0.0065 atm, and 0.0045 atm, respectively, at equilibrium. What is the value of the equilibrium constant, KP, for this reaction at this temperature?
2H2O(g)   ⇆\leftrightarrows⇆  2H2(g)  + O2(g)

Accepted Answer

A)   5.3 *10-4
B)   3.5 *10-6
C)   6.3*10-5
D)   1.6 *104
E)   3.0 *104

Question 8

Write the equilibrium expression for the reaction
Zn2+(aq)  + 2 NH3(aq)   ⇆\leftrightarrows⇆  Zn(NH3) 2+(aq)

Accepted Answer

A)    K=[Zn2+]+2[NH3]+[Zn(NH3) 2+]K = \left[ \mathrm { Zn } ^ { 2 + } \right] + 2 \left[ \mathrm { NH } _ { 3 } \right] + \left[ \mathrm { Zn } \left( \mathrm { NH } _ { 3 } \right)  ^ { 2 + } \right]K=[Zn2+]+2[NH3​]+[Zn(NH3​) 2+] 
B)    K=[Zn2+]+2[NH3][Zn(NH3) 2+]K = \frac { \left[ \mathrm { Zn } ^ { 2 + } \right] + 2 \left[ \mathrm { NH } _ { 3 } \right] } { \left[ \mathrm { Zn } \left( \mathrm { NH } _ { 3 } \right)  ^ { 2 + } \right] }K=[Zn(NH3​) 2+][Zn2+]+2[NH3​]​ 
C)    K=[Zn2+][NH3]2[Zn(NH3) 2+]K = \frac { \left[ \mathrm { Zn } ^ { 2 + } \right] \left[ \mathrm { NH } _ { 3 } \right] ^ { 2 } } { \left[ \mathrm { Zn } \left( \mathrm { NH } _ { 3 } \right)  ^ { 2 + } \right] }K=[Zn(NH3​) 2+][Zn2+][NH3​]2​ 
D)    K=[Zn(NH3) 2+][Zn2+][NH3]2K = \frac { \left[ \mathrm { Zn } \left( \mathrm { NH } _ { 3 } \right)  ^ { 2 + } \right] } { \left[ \mathrm { Zn } ^ { 2 + } \right] \left[ \mathrm { NH } _ { 3 } \right] ^ { 2 } }K=[Zn2+][NH3​]2[Zn(NH3​) 2+]​ 
E)    K=[Zn(NH3) 2+]−[Zn2+]−2[NH3]K = \left[ \mathrm { Zn } \left( \mathrm { NH } _ { 3 } \right)  ^ { 2 + } \right] - \left[ \mathrm { Zn } ^ { 2 + } \right] - 2 \left[ \mathrm { NH } _ { 3 } \right]K=[Zn(NH3​) 2+]−[Zn2+]−2[NH3​]

Question 9

The water gas shift reaction shown below can be used to produce hydrogen from water and coal. Given the data in the following table, which experiment will proceed in the forward direction to produce more hydrogen? Under the experimental conditions, Kc = 25 for this reaction.
H2O(g)  + CO(g)   ⇆\leftrightarrows⇆  H2(g)  + CO2(g) 
Initial Concentrations (mol/L)    Experiment [H2O][CO][H2][CO2] I 0.0300.03000 II 000.0300.030 III 0.0200.0200.0500.040 IV 0.0300.0200.0300.020\begin{array} { | c | c | c | c | c | } \hline 	ext { Experiment } & { \left[ \mathrm { H } _ { 2 } \mathrm { O } ight] } & { [ \mathrm { CO } ] } & { \left[ \mathrm { H } _ { 2 } ight] } & { \left[ \mathrm { CO } _ { 2 } ight] } \\hline 	ext { I } & 0.030 & 0.030 & 0 & 0 \\hline 	ext { II } & 0 & 0 & 0.030 & 0.030 \\hline 	ext { III } & 0.020 & 0.020 & 0.050 & 0.040 \\hline 	ext { IV } & 0.030 & 0.020 & 0.030 & 0.020 \\hline\end{array} Experiment  I  II  III  IV ​[H2​O]0.03000.0200.030​[CO]0.03000.0200.020​[H2​]00.0300.0500.030​[CO2​]00.0300.0400.020​​

Accepted Answer

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

Question 10

A 10.0 L flask at 500 K is filled with 0.30 mol of hydrogen and 0.30 mol of iodine. They react as indicated below. The equilibrium constant Kc = 45.0. What are the equilibrium concentrations of the three gases?
H2(g)  + I2(g)   ⇆\leftrightarrows⇆  2HI(g)

Accepted Answer

A)   [H2] = [I2] = 0.023 M, [HI] = 0.046 M
B)   [H2] = [I2] = 0.0069 M, [HI] = 0.046 M
C)   [H2] = [I2] = [HI] = 0.023 M
D)   [H2] = [I2] = 0.0069 M, [HI] = 0.023 M
E)   [H2] = [I2] = 0.23 M, [HI] = 0.46 M

Question 11

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

Accepted Answer

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 removal of products.

Question 12

Lime is obtained ________

Accepted Answer

A)   by heating calcium sulfite at 900 °\degree° C.
B)   as a by-product of burning coal.
C)   from the reaction between calcium oxide and sulfur dioxide.
D)   by heating calcium carbonate at 900 °\degree° C.
E)   from sweet soil.

Question 13

The equilibrium constant for the acid ionization of mercaptoethanol (HSCH2CH2OH )  is 1.91 *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.

Accepted Answer

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 14

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

Accepted Answer

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 15

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

Accepted Answer

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

Question 16

Which of the listed perturbations would change the value of the equilibrium constant for the following reaction? List those that do as a sequence of letters,
e.g., ACE.
NH4CO2NH2(s) $\leftrightarrows$ 
2NH3(g) + CO2(g)
(A) Increasing the quantity of NH4CO2NH2(s)
(B) Removing CO2(g)
(C) Increasing the total pressure by adding argon gas
(D) Increasing the volume of the container
(E) Increasing the temperature

Accepted Answer

Question 17

How and why are the expressions for homogeneous equilibrium constants different from the expressions for heterogeneous equilibrium constants?

Accepted Answer

Heterogeneous equilibrium cons...

Question 18

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

Accepted Answer

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 19

Identify the equilibrium expression for the following reaction, assuming homogeneity:
Boy + girl  ⇆\leftrightarrows⇆  Couple

Accepted Answer

A)    K=[ boy ][ girl ][ couple ]K = \frac { [ 	ext { boy } ] [ 	ext { girl } ] } { [ 	ext { couple } ] }K=[ couple ][ boy ][ girl ]​ 
B)    K=[ boy ]+[ girl ][ couple ]K = \frac { [ 	ext { boy } ] + [ 	ext { girl } ] } { [ 	ext { couple } ] }K=[ couple ][ boy ]+[ girl ]​ 
C)    K=[ boy ][ girl ][ couple ]K = [ 	ext { boy } ] [ 	ext { girl } ] [ 	ext { couple } ]K=[ boy ][ girl ][ couple ] 
D)    K=[ couple ][ boy ][ girl ]K = \frac { [ 	ext { couple } ] } { [ 	ext { boy } ] [ 	ext { girl } ] }K=[ boy ][ girl ][ couple ]​ 
E)    K=[ couple ]−[ boy ]−[ girl ]K = [ 	ext { couple } ] - [ 	ext { boy } ] - [ 	ext { girl } ]K=[ couple ]−[ boy ]−[ girl ]

Question 20

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

Accepted Answer

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.

Exam 15: Chemical Equilibrium: How Much Product Does a Reaction Really Make

Correct Answer
verified

A 10.0 L flask at 500 K is filled with 0.30 mol of hydrogen and 0.30 mol of iodine. They react as indicated below. The equilibrium constant K_c = 45.0. What are the equilibrium concentrations of the three gases? H₂(g) + I₂(g) $\leftrightarrows$ 2HI(g)

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

Correct Answer
verified

How and why are the expressions for homogeneous equilibrium constants different from the expressions for heterogeneous equilibrium constants?

Correct Answer
verified
Heterogeneous equilibrium cons...
View Answer

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

Correct Answer
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Correct Answer
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Increasing the temperature of an exothermic reaction results in ________

Correct Answer
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Lime is obtained ________

Correct Answer
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Correct Answer
verified

Correct Answer
verified

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

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

Correct Answer
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Identify the equilibrium expression for the following reaction, assuming homogeneity: Boy + girl $\leftrightarrows$ Couple

Correct Answer
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The sulfide ion, S²^-, reacts with water as a weak base: S²^- + H₂O $\leftrightarrows$ SH^- + OH^-K = 1.0 If sodium sulfide were dissolved in water to make a solution of 0.50 M, what would be the resulting concentration of OH^-?

Correct Answer
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Write the equilibrium expression for the reaction Zn²⁺(aq) + 2NH₃(aq) $\leftrightarrows$ Zn(NH₃) ²⁺(aq)

Correct Answer
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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?

Correct Answer
verified

A chemical equilibrium 2A $\leftrightarrows$ B Has a forward rate constant, k_f = 10 M ^-¹s^-¹, and a reverse rate constant, k_r = 5.0 s^-¹. What is the value of the equilibrium constant for this system?

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

Exam 15: Chemical Equilibrium: How Much Product Does a Reaction Really Make

Correct AnswerverifiedShow Answer

A 10.0 L flask at 500 K is filled with 0.30 mol of hydrogen and 0.30 mol of iodine. They react as indicated below. The equilibrium constant Kc = 45.0. What are the equilibrium concentrations of the three gases? H2(g) + I2(g) ⇆\leftrightarrows⇆ 2HI(g)

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

How and why are the expressions for homogeneous equilibrium constants different from the expressions for heterogeneous equilibrium constants?

Correct AnswerverifiedHeterogeneous equilibrium cons...View AnswerShow Answer

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

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Increasing the temperature of an exothermic reaction results in ________

Correct AnswerverifiedShow Answer

Lime is obtained ________

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Identify the equilibrium expression for the following reaction, assuming homogeneity: Boy + girl ⇆\leftrightarrows⇆ Couple

Correct AnswerverifiedShow Answer

The sulfide ion, S2-, reacts with water as a weak base: S2- + H2O ⇆\leftrightarrows⇆ SH- + OH- K = 1.0 If sodium sulfide were dissolved in water to make a solution of 0.50 M, what would be the resulting concentration of OH-?

Correct AnswerverifiedShow Answer

Write the equilibrium expression for the reaction Zn2+(aq) + 2 NH3(aq) ⇆\leftrightarrows⇆ Zn(NH3) 2+(aq)

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

A chemical equilibrium 2 A ⇆\leftrightarrows⇆ B Has a forward rate constant, kf = 10 M -1s-1, and a reverse rate constant, kr = 5.0 s-1. What is the value of the equilibrium constant for this system?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Correct Answer
verified

A 10.0 L flask at 500 K is filled with 0.30 mol of hydrogen and 0.30 mol of iodine. They react as indicated below. The equilibrium constant K_c = 45.0. What are the equilibrium concentrations of the three gases? H₂(g) + I₂(g) $\leftrightarrows$ 2HI(g)

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
Heterogeneous equilibrium cons...
View Answer

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

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Identify the equilibrium expression for the following reaction, assuming homogeneity: Boy + girl $\leftrightarrows$ Couple

Correct Answer
verified

The sulfide ion, S²^-, reacts with water as a weak base: S²^- + H₂O $\leftrightarrows$ SH^- + OH^-K = 1.0 If sodium sulfide were dissolved in water to make a solution of 0.50 M, what would be the resulting concentration of OH^-?

Correct Answer
verified

Write the equilibrium expression for the reaction Zn²⁺(aq) + 2NH₃(aq) $\leftrightarrows$ Zn(NH₃) ²⁺(aq)

Correct Answer
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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?

Correct Answer
verified

A chemical equilibrium 2A $\leftrightarrows$ B Has a forward rate constant, k_f = 10 M ^-¹s^-¹, and a reverse rate constant, k_r = 5.0 s^-¹. What is the value of the equilibrium constant for this system?

Correct Answer
verified

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

Correct Answer
verified

Correct Answer
verified