Deck 17: Equilibrium: the Extent of Chemical Reactions

Question 1

There is a direct correlation between the speed of a reaction and its equilibrium constant.

Answer 1

False

Question 2

Consider the equilibrium reaction shown below. B₂(g) ⇄ 2B(g)
If the rate constants are: k_fwd = 7.00 × 10⁻⁵s⁻¹ and k_rev = 2.00 × 10⁻⁵ L mol⁻¹ s⁻¹, what is the value of K_c under these conditions?

A)1.75 × 10 ⁵
B)3.50
C)0.286
D)5.71 × 10 ⁻⁶
E)1.40 × 10 ⁻¹⁰

Answer 2

3.50

Question 3

If all of the coefficients in the balanced equation for an equilibrium reaction are doubled, then the value of the equilibrium constant, K_c, will also be doubled.

Answer 3

False

Question 4

Changing the amount of a solid reactant or product in an equilibrium reaction will not affect the amounts of the other reactants and products present at equilibrium.

Question 5

Increasing the initial amount of the limiting reactant in a reaction will increase the value of the equilibrium constant, K_c.

Question 6

For a gas-phase equilibrium, a change in the pressure of any single reactant or product will affect the amounts of other substances involved in the equilibrium.

Question 7

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

Question 8

For some gas-phase reactions, K_p = K_c.

Question 9

In a chemical reaction, if the starting concentrations of reactants are increased, then the equilibrium constant K_c will also increase.

Question 10

For a solution equilibrium, a change in concentration of a reactant or product does not change K_c.

Question 11

If Q > K, more products need to be formed as the reaction proceeds to equilibrium.

Question 12

A good catalyst for a reaction will speed up the forward reaction and slow down the reverse reaction.

Question 13

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

Question 14

For a gas-phase equilibrium, a change in the pressure of any single reactant or product will change K_p.

Question 15

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

Question 16

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

Question 17

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

Question 18

A chemical reaction will reach equilibrium when the limiting reactant is used up.

Question 19

An equilibrium is established in which both the forward (fwd) and the reverse (rev) reactions are elementary. If the equilibrium constant K_c = 1.6 × 10⁻² and the rate constant k_fwd = 8.0 × 10⁻⁷ s⁻¹ what is the value of k_rev?

A)1.3 × 10 ⁻⁸ s ⁻¹
B)7.8 × 10 ⁷ s ⁻¹
C)2 × 10 ⁴ s ⁻¹
D)5.0 × 10 ⁻⁵ s ⁻¹
E)None of these choices are correct.

Question 20

Unless ΔH°_rxn = 0, a change in temperature will affect the value of the equilibrium constant K_c.

Question 21

Write the mass-action expression, Q_c, for the following chemical reaction. 3ClO₂⁻(aq) ⇄ 2ClO₃⁻(aq) + Cl⁻(aq)

A)
B)
C)
D)
E)

Question 22

Which of the following has an effect on the magnitude of the equilibrium constant?

A)Removing products as they are formed
B)Adding more of a reactant
C)Adding a catalyst
D)Increasing the pressure, in a gas-phase reaction
E)Change in temperature

Question 23

Write the mass-action expression, Q_c, for the following chemical reaction equation. 2C₆H₆(g) + 15O₂(g) ⇄ 12CO₂(g) + 6H₂O(g)

A)
B)
C)
D)
E)

Question 24

The two equilibrium constants for the same reaction, K_c and K_p, will always equal one another when

A)all of the reactants and products are gases.
B)in the reaction equation, the number of moles of gaseous products equals the number of moles of gaseous reactants.
C)in the reaction equation, the number of moles of gaseous products is greater than the number of moles of gaseous reactants.
D)in the reaction equation, the number of moles of gaseous products is smaller than the number of moles of gaseous reactants.
E)in the reaction equation, the total number of moles of reactants equals that of the products.

Question 25

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?

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.

Question 26

What is the mass-action expression, Q_c, for the following chemical reaction? 4H₃O⁺(aq) + 2Cl⁻(aq) + MnO₂(s) ⇄ Mn²⁺(aq) + 6H₂O(l) + Cl₂(g)

A)
B)
C)
D)
E)None of these choices are correct.

Question 27

A chemical reaction has an equilibrium constant of 2 × 10⁶. If this reaction is at equilibrium, select the one correct conclusion that can be made about the reaction.

A)The forward and back reactions have stopped.
B)The limiting reactant has been used up.
C)The forward and reverse rate constants are equal.
D)The forward and reverse reaction rates are equal.
E)None of these choices are correct.

Question 28

Carbon monoxide and chlorine combine in an equilibrium reaction to produce the highly toxic product, phosgene (COCl₂) CO(g) + Cl₂(g) ⇄ COCl₂(g)
If the equilibrium constant for this reaction is K_c = 248, predict, if possible, what will happen when the reactants and product are combined with the concentrations shown.
[CO] = [Cl₂] = 0.010 M; [COCl₂] = 0.070 M

A)The reaction will proceed to the right.
B)The reaction will proceed to the left.
C)The reaction is at equilibrium, and no change in concentrations will occur.
D)The container volume needs to be specified before a prediction can be made.
E)The temperature needs to be specified before a prediction can be made.

Question 29

The reaction quotient, Q_c, for a reaction has a value of 75 while the equilibrium constant, K_c, has a value of 195. Which of the following statements is accurate?

A)The reaction must proceed to the left to establish equilibrium.
B)The reaction must proceed to the right to establish equilibrium.
C)The concentrations of the products will be much smaller than the concentrations of the reactants when the system is at equilibrium.
D)The concentrations of the products will be about the same as the concentrations of the reactants when the system is at equilibrium.
E)None of these choices are correct.

Question 30

What is the mass-action expression, Q_c, for the following chemical reaction? PbO(s) + CO(g) ⇄ Pb(l) + CO₂(g)

A)
B)
C)
D)
E)None of these choices are correct.

Question 31

Write the mass-action expression, Q_c, for the following chemical reaction. MgO(s) + SO₂(g) + ½O₂(g) ⇄ MgSO₄(s)

A)
B)
C)
D)
E)None of these choices are correct.

Question 32

In order to write the correct mass-action expression for a reaction one must

A)know the kinetic rate law for the reaction.
B)know the mechanism for the reaction.
C)have a properly balanced chemical equation.
D)have values for the concentrations of the reactants.
E)know the limiting reactant.

Question 33

Write the mass-action expression, Q_c, for the following chemical reaction. 2Cu²⁺(aq) + 4I⁻(aq) ⇄ 2CuI(s) + I₂(aq)

A)
B)
C)
D)
E)

Question 34

Write the mass-action expression, Q_c, for the following chemical reaction. Fe³⁺(aq) + 3OH⁻(aq) ⇄ Fe(OH)₃(s)

A)
B)
C)
D)
E)

Question 35

What is the mass-action expression, Q_p, for the following reaction? SbF₅(g) + 4Cl₂(g) ⇄ SbCl₃(g) + 5ClF(g)

A)
B)
C)
D)
E)None of these choices are correct.

Question 36

What is the mass-action expression, Q_c, for the following chemical reaction? Cu²⁺(aq) + 4NH₃(aq) ⇄ Cu(NH₃)₄²⁺(aq)

A)
B)
C)
D)
E)None of these choices are correct.

Question 37

Carbon monoxide and chlorine combine in an equilibrium reaction to produce the highly toxic product, phosgene (COCl₂) CO(g) + Cl₂(g) ⇄ COCl₂(g)
If the equilibrium constant for this reaction is K_c = 248, predict, if possible, what will happen when the reactants and product are combined with the concentrations shown.
[CO] = [Cl₂] = 0.0200 M; [COCl₂] = 0.0992 M

A)The reaction will proceed to the right.
B)The reaction will proceed to the left.
C)The reaction is at equilibrium, and no change in concentrations will occur.
D)The container volume needs to be specified before a prediction can be made.
E)The temperature needs to be specified before a prediction can be made.

Question 38

When a chemical system is at equilibrium,

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.

Question 39

Write the mass-action expression, Q_c, for the following chemical reaction. Zn(s) + 2Ag⁺(aq) ⇄ Zn²⁺(aq) + 2Ag(s)

A)
B)
C)
D)
E)

Question 40

Write the mass-action expression, Q_c, for the following chemical reaction. NO(g) + ½Br₂(g) ⇄ NOBr(g)

A)
B)
C)
D)
E)

Question 41

Consider the equilibrium reaction: H₂(g) + Br₂(g) ⇄ 2HBr(g) Which of the following correctly describes the relationship between K_c and K_p for the reaction?

A)K _p = K _c
B)K _p = ( RT)K _c
C)K _p = ( RT)² K _c
D)K _p = K _c / RT
E)K _p = K _c / ( RT)²

Question 42

The equilibrium constant for the reaction of bromine with chlorine to form bromine monochloride is 58.0 at a certain temperature. Br₂(g) + Cl₂(g) ⇄ 2BrCl(g)
What is the equilibrium constant for the following reaction?
BrCl(g) ⇄ ½Br₂(g) + ½Cl₂(g)

A)2.97 × 10 ⁻⁴
B)1.72 × 10 ⁻²
C)3.45 × 10 ⁻²
D)1.31 × 10 ⁻¹
E)> 1.00

Question 43

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?

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)²

Question 44

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)

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

Question 45

The equilibrium constant for reaction (1) below is 276. Under the same conditions, what is the equilibrium constant of reaction (2)? (1) ½X₂(g) + ½Y₂(g) ⇄ XY(g)
(2) 2XY(g) ⇄ X₂(g) + Y₂(g)

A)6.02 × 10 ⁻²
B)7.25 × 10 ⁻³
C)3.62 × 10 ⁻³
D)1.31 × 10 ⁻⁵
E)None of these choices are correct.

Question 46

In water, the following equilibrium exists: H⁺(aq) + OH⁻(aq) ⇄ H₂O(l)
In pure water at 25°C, the concentration of H⁺ ions is 1.00 × 10⁻⁷ mol/L. Calculate the value of the equilibrium constant for the reaction as written above.

A)1.00 × 10 ¹⁴
B)1.00 × 10 ¹²
C)1.00 × 10 ⁻¹⁴
D)1.00 × 10 ⁻¹²
E)5.55 × 10 ¹⁵

Question 47

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)?

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.

Question 48

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)

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

Question 49

The equilibrium constant, K_p, for the reaction H₂(g) + I₂(g) ⇄ 2HI(g)
Is 55.2 at 425°C. A rigid cylinder at that temperature contains 0.127 atm of hydrogen, 0.134 atm of iodine, and 1.055 atm of hydrogen iodide. Is the system at equilibrium?

A)Yes.
B)No, the forward reaction must proceed to establish equilibrium.
C)No, the reverse reaction must proceed to establish equilibrium.
D)Need to know the volume of the container before deciding.
E)Need to know the starting concentrations of all substances before deciding.

Question 50

The equilibrium constant, K_p, has a value of 6.5 × 10⁻⁴ at 308 K for the reaction of nitrogen monoxide with chlorine. 2NO(g) + Cl₂(g) ⇄ 2NOCl(g)
What is the value of K_c?

A)2.5 × 10 ⁻⁷
B)6.5 × 10 ⁻⁴
C)1.6 × 10 ⁻²
D)1.7
E)None of these choices are correct.

Question 51

Nitrogen dioxide decomposes according to the reaction 2NO₂(g) ⇄ 2NO(g) + O₂(g)
Where K_p = 4.48 × 10⁻¹³ at 25°C. What is the value for K_c?

A)1.81 × 10 ⁻¹⁶
B)1.83 × 10 ⁻¹⁴
C)4.48 × 10 ⁻¹³
D)1.10 × 10 ⁻¹¹
E)1.11 × 10 ⁻⁹

Question 52

Write the mass-action expression, Q_c, for the following chemical reaction. Sn²⁺(aq) + ½O₂(g) + 3H₂O(l) ⇄ SnO₂(s) + 2H₃O⁺(aq)

A)
B)
C)
D)
E)None of these choices are correct.

Question 53

Hydrogen sulfide will react with water as shown in the following reactions. H₂S(g) + H₂O(l) ⇄ H₃O⁺(aq) + HS⁻(aq) K₁ = 1.0 × 10⁻⁷
HS⁻(aq) + H₂O(l) ⇄ H₃O⁺(aq) + S²⁻(aq) K₂ = ?
H₂S(g) + 2H₂O(l) ⇄ 2H₃O⁺(aq) + S²⁻(aq) K₃ = 1.3 × 10⁻²⁰
What is the value of K₂?

A)1.3 × 10 ⁻²⁷
B)2.3 × 10 ⁻⁷
C)1.3 × 10 ⁻¹³
D)7.7 × 10 ¹²
E)7.7 × 10 ²⁶

Question 54

Consider the following two equilibria and their respective equilibrium constants: (1) NO(g) + ½O₂(g) ⇄ NO₂(g)
(2) 2NO₂(g) ⇄ 2NO(g) + O₂(g)
Which one of the following is the correct relationship between the equilibrium constants K₁ and K₂?

A)K ₂ = 2/ K ₁
B)K ₂ = (1/ K ₁)²
C)K ₂ = − K ₁/2
D)K ₂ = 1/(2 K ₁)
E)K ₂ = 1/(2 K ₁)²

Question 55

The reaction of nitrogen with oxygen to form nitrogen monoxide can be represented by the following equation. N₂(g) + O₂(g) ⇄ 2NO(g)
At 2000°C, the equilibrium constant, K_c, has a value of 4.10 × 10⁻⁴. What is the value of K_p?

A)2.17 × 10 ⁻⁸
B)4.10 × 10 ⁻⁴
C)7.65 × 10 ⁻²
D)7.75
E)None of these choices are correct.

Question 56

The equilibrium constant, K_p, for the reaction CO(g) + H₂O(g) ⇄ CO₂(g) + H₂(g)
At 986°C is 0.63. A rigid cylinder at that temperature contains 1.2 atm of carbon monoxide, 0.20 atm of water vapor, 0.30 atm of carbon dioxide, and 0.27 atm of hydrogen. Is the system at equilibrium?

A)Yes.
B)No, the forward reaction must proceed to establish equilibrium.
C)No, the reverse reaction must proceed to establish equilibrium.
D)Need to know the volume of the container before deciding.
E)Need to know the starting concentrations of all substances before deciding.

Question 57

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)?

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.

Question 58

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)

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

Question 59

Consider the equilibrium reaction: N₂O₄(g) ⇄ 2NO₂(g) Which of the following correctly describes the relationship between K_c and K_p for the reaction?

A)K _p = K _c
B)K _p = RT × K _c
C)K _p = ( RT × K _c)⁻¹
D)K _p = K _c / RT
E)K _p = RT / K _c

Question 60

The equilibrium constant, K_c, for the decomposition of COBr₂ COBr₂(g) ⇄ CO(g) + Br₂(g)
Is 0.190. What is K_c for the following reaction?
2CO(g) + 2Br₂(g) ⇄ 2COBr₂(g)

A)0.0361
B)2.63
C)5.62
D)10.5
E)27.7

Question 61

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?

A)0.309
B)0.601
C)1.66
D)3.24
E)> 10

Question 62

10.0 mL of a 0.100 mol L⁻¹ solution of a metal ion M²⁺ is mixed with 10.0 mL of a 0.100 mol L⁻¹ solution of a substance L. The following equilibrium is established: M²⁺(aq) + 2L(aq) ⇄ ML₂²⁺(aq)
At equilibrium the concentration of L is found to be 0.0100 mol L⁻¹. What is the equilibrium concentration of ML₂²⁺, in mol L⁻¹?

A)0.100 mol L ⁻¹
B)0.050 mol L ⁻¹
C)0.025 mol L ⁻¹
D)0.0200 mol L ⁻¹
E)0.0100 mol L ⁻¹

Question 63

SO₂ reacts with O₂ to produce SO₃. If 86.0 g of SO₂ is placed in a reaction vessel along with excess oxygen gas, how many moles of SO₂ remain when 50.0 g of SO₃ have been formed?

A)0.56 mol
B)0.62 mol
C)0.72 mol
D)0.78 mol
E)1.34 mol

Question 64

Nitric oxide is formed in automobile exhaust when nitrogen and oxygen in air react at high temperatures. N₂(g) + O₂(g) ⇄ 2NO(g)
The equilibrium constant K_p for the reaction is 0.0025 at 2127°C. If a container is charged with 8.00 atm of nitrogen and 5.00 atm of oxygen and the mixture is allowed to reach equilibrium, what will be the equilibrium partial pressure of nitrogen?

A)0.16 atm
B)0.31 atm
C)3.1 atm
D)7.7 atm
E)7.8 atm

Question 65

Hydrogen iodide, HI, is formed in an equilibrium reaction when gaseous hydrogen and iodine gas are heated together. If 20.0 g of hydrogen and 20.0 g of iodine are heated, forming 10.0 g of hydrogen iodide, what mass of hydrogen remains unreacted?

A)10.0 g hydrogen remains
B)10.9 g hydrogen remains
C)15.0 g hydrogen remains
D)19.9 g hydrogen remains
E)Need to know the equilibrium constant in order to calculate the answer.

Question 66

At 25°C, the equilibrium constant K_c for the reaction 2A(aq) ⇄ B(aq) + C(aq)
Is 65. If 2.50 mol of A is added to enough water to prepare 1.00 L of solution, what will the equilibrium concentration of A be?

A)0.038 M
B)0.14 M
C)0.28 M
D)1.18 M
E)2.4 M

Question 67

The reaction system POCl₃(g) ⇄ POCl(g) + Cl₂(g)
Is at equilibrium. Which of the following statements describes the behavior of the system if POCl is added to the container?

A)The forward reaction will proceed to establish equilibrium.
B)The reverse reaction will proceed to establish equilibrium.
C)The partial pressures of POCl ₃ and POCl will remain steady while the partial pressure of chlorine increases.
D)The partial pressure of chlorine remains steady while the partial pressures of POCl ₃ and POCl increase.
E)The partial pressure of chlorine will increase while the partial pressure of POCl decreases.

Question 68

A mixture of 0.600 mol of bromine and 1.600 mol of iodine is placed into a rigid 1.000-L container at 350°C. Br₂(g) + I₂(g) ⇄ 2IBr(g)
When the mixture has come to equilibrium, the concentration of iodine monobromide is 1.190 M. What is the equilibrium constant for this reaction at 350°C?

A)3.55 × 10 ⁻³
B)1.24
C)1.47
D)282
E)325

Question 69

The equilibrium constant K_c 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?

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

Question 70

The equilibrium constant K_c for the reaction A(g) + B(g) ⇄ C(g)
Is 0.76 at 150°C. If 0.800 mol of A is added to 0.600 mol of B in a 1.00-L container at 150°C, what will be the equilibrium concentration of C?

A)0.19 M
B)0.29 M
C)0.36 M
D)0.41 M
E)0.51 M

Question 71

Consider the reversible reaction: 2NO₂(g) ⇄ N₂O₄(g) If the concentrations of both NO₂ and N₂O₄ are 0.016 mol L⁻¹, what is the value of Q_c?

A)0.016
B)0.50
C)1.0
D)2.0
E)63

Question 72

The following reaction, in CCl₄ solvent, has been studied at 25°C. 2BrCl ⇄ Br₂ + Cl₂
The equilibrium constant K_c is known to be 0.141. If the initial concentration of chlorine is 0.0300 M and of bromine monochloride is 0.0200 M, what is the equilibrium concentration of bromine?

A)1.35 × 10 ⁻³ M
B)2.70 × 10 ⁻³ M
C)8.82 × 10 ⁻³ M
D)9.70 × 10 ⁻² M
E)None of these choices are correct.

Question 73

The reaction system POCl₃(g) ⇄ POCl(g) + Cl₂(g)
Is at equilibrium. Which of the following statements describes the behavior of the system if the partial pressure of chlorine is reduced by 50%?

A)POCl ₃ will be consumed as equilibrium is established.
B)POCl will be consumed as equilibrium is established.
C)Chlorine will be consumed as equilibrium is established.
D)The partial pressure of POCl will decrease while the partial pressure of Cl ₂ increases as equilibrium is established.
E)The volume will have to decrease before equilibrium can be reestablished.

Question 74

At high temperatures, carbon reacts with O₂ to produce CO as follows: C(s) + O₂(g) ⇄ 2CO(g).
When 0.350 mol of O₂ and excess carbon were placed in a 5.00-L container and heated, the equilibrium concentration of CO was found to be 0.060 M. What is the equilibrium constant, K_c, for this reaction?

A)0.010
B)0.072
C)0.090
D)0.17
E)1.2

Question 75

At 25°C, the equilibrium constant K_c for the reaction 2A(g) ⇄ B(g) + C(g)
Is 0.035. A mixture of 8.00 moles of B and 12.00 moles of C in a 20.0 L container is allowed to come to equilibrium. What is the equilibrium concentration of A?

A)< 0.100 M
B)0.339 M
C)0.678 M
D)6.78 M
E)13.56 M

Question 76

At 850°C, the equilibrium constant K_p for the reaction C(s) + CO₂(g) ⇄ 2CO(g)
Has a value of 10.7. If the total pressure in the system at equilibrium is 1.000 atm, what is the partial pressure of carbon monoxide?

A)0.362 atm
B)0.489 atm
C)0.667 atm
D)0.915 atm
E)0.921 atm

Question 77

At a certain temperature the reaction CO₂(g) + H₂(g) ⇄ CO(g) + H₂O(g)₂
Has K_c = 2.50. If 2.00 mol of carbon dioxide and 1.5 mol of hydrogen are placed in a 5.00 L vessel and equilibrium is established, what will be the concentration of carbon monoxide?

A)0.091 M
B)0.191 M
C)0.209 M
D)0.913 M
E)1.05 M

Question 78

The reaction system CS₂(g) + 4H₂(g) ⇄ CH₄(g) + 2H₂S(g)
Is at equilibrium. Which of the following statements describes the behavior of the system if the partial pressure of hydrogen is doubled?

A)As equilibrium is reestablished, the partial pressure of carbon disulfide increases.
B)As equilibrium is reestablished, the partial pressure of methane, CH ₄, decreases.
C)As equilibrium is reestablished, the partial pressure of hydrogen decreases.
D)As equilibrium is reestablished, the partial pressure of hydrogen sulfide decreases.
E)As equilibrium is reestablished, all the partial pressures will decrease.

Question 79

Ammonium iodide dissociates reversibly to ammonia and hydrogen iodide. NH₄I(s) ⇄ NH₃(g) + HI(g)
At 400°C, K_p = 0.215. Calculate the partial pressure of ammonia at equilibrium when a sufficient quantity of ammonium iodide is heated to 400°C.

A)0.103 atm
B)0.215 atm
C)0.232 atm
D)0.464 atm
E)2.00 atm

Question 80

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 the value of K_c for this reaction? CO(g) + Br₂(g) ⇄ COBr₂(g)

A)5.23
B)1.22
C)1.165
D)0.858
E)0.191