General Chemistry: Atoms First, 2e (McMurry and Fay)
Chapter 13 Chemical Equilibrium: The Extent of Chemical Reactions
13.1 Multiple Choice Questions
1) Which one of the following statements does not describe the equilibrium state?
A) Equilibrium is dynamic and there is no net conversion to reactants and products.
B) The concentration of the reactants is equal to the concentration of the products.
C) The concentration of the reactants and products reach a constant level.
D) The rate of the forward reaction is equal to the rate of the reverse reaction.
2) The equilibrium equation is also known as the law of
A) coefficients.
B) constant concentration.
C) dynamic equilibrium.
D) mass action.
3) Which of the following statements is false regarding the equilibrium constant, Kc?
A) Kc for a reaction at a particular temperature always has the same value.
B) Kc for the reverse reaction is the negative of Kc for the forward reaction.
C) The numerical value of Kc depends on the form of the balanced equation.
D) When quoting Kc it is customary to omit units.
4) Which statement about the equilibrium constant is true? The value of Kc
A) changes as product concentration changes.
B) changes as reactant concentration changes.
C) changes as temperature changes.
D) never changes.
5) If Kc is the equilibrium constant for a forward reaction what is Kc‘ for the reverse reaction?
A) –Kc
B) Kc
C) (Kc)-1
D) none of these
6) If Kc is the equilibrium constant for a forward reaction, 2 A⇌ B, what is Kc” for the reaction 4
A⇌ 2B?
A) Kc
B) Kc
C) 2 Kc
D) (Kc)2
7) Write the equilibrium constant expression for the following reaction in the forward direction:
2 CH4 (g) + 3 O2 (g) ⇌ 2 CO (g) + 4 H2O (g)
A) Kc =
B) Kc =
C) Kc =
D) Kc =
8) Write the equilibrium constant expression for the following reaction in the reverse direction:
2 CH4 (g) + 3 O2 (g) ⇌ 2 CO (g) + 4 H2O (g)
A) Kc‘ =
B) Kc‘ =
C) Kc‘ =
D) Kc‘ =
9) Nitric oxide reacts with oxygen to form nitrogen dioxide:
2 NO(g) + O2(g) ⇌ 2 NO2(g)
What is Kc for the forward reaction if the equilibrium concentration of NO is 0.200 M, O2 is
0.100 M, and NO2 is 0.250 M at 25°C?
A) 8.00 × 10-2
B) 6.41 × 10-2
C) 12.5
D) 15.6
10) Nitric oxide reacts with oxygen to form nitrogen dioxide:
2 NO(g) + O2(g) ⇌ 2 NO2(g)
What is Kc‘ for the reverse reaction if the equilibrium concentration of NO is 0.300 M, O2 is
0.200 M, and NO2 is 0.530 M at ?
A) 0.0340
B) 0.0641
C) 0.624
D) 15.6
4
11) A mixture of carbon monoxide, hydrogen, and methanol is at equilibrium. The balanced
chemical equation is: . At 250°C, the mixture contains 0.0960 M CO,
0.191 M H2, and 0.150 M CH3OH. What is the value for Kc?
A) 2.33 × 10-2
B) 0.244
C) 4.09
D) 42.8
12) Given the reaction: 2 HI ⇌ H2 + I2. If Kc‘ for the reverse reaction is 1.85 × 10-2 at 425°C,
what is Kc for the forward reaction at the same temperature?
A) -1.85 × 10-2
B) 1.85 × 10-2
C) 3.70 × 10-2
D) 54.1
13) For the reaction: N2(g) + 2 O2(g) ⇌ 2 NO2(g), Kc = 8.3 × 10-10 at 25°C. What is the
concentration of N2 gas at equilibrium when the concentration of NO2 is twice the concentration
of O2 gas?
A) 2.1 × 10-10 M
B) 4.2 × 10-10 M
C) 2.4 × 109 M
D) 4.8 × 109 M
14) If Kc = 7.04 × 10-2 for the reaction: 2 HBr(g) ⇌ H2(g) + Br2(g), what is the value of Kc for
the reaction: ?
A) 3.52 × 10-2
B) 0.265
C) 3.77
D) 28.4
15) If Kc equals 0.11 at 25°C for the reaction: N2O4(g) ⇌ 2 NO2(g), what is Kc for the reaction:
NO2(g) ⇌ 1/2 N2O4(g)?
A) 0.33
B) 3.0
C) 4.5
D) 9.1
16) Which one of the following statements about the equilibrium constant, Kp, is false?
A) Δn is equal to the sum of the coefficients of the gaseous products minus the sum of the
coefficients of the gaseous reactants.
B) The relationship between Kp and Kc is: Kp = Kc (RT)Δn
C) The units for Kp are usually omitted.
D) Total pressures are used in the equilibrium equation in place of molar concentrations.
17) Write the equilibrium constant expression for the following reaction in the forward
direction:
2 CH4(g) + 3 O2(g) ⇌ 2 CO(g) + 4 H2O(g)
A) Kp =
B) Kp=
C) Kp =
D) Kp =
18) Write the equilibrium constant expression for the following reaction in the reverse direction:
2 CH4(g) + 3 O2(g) ⇌ 2 CO(g) + 4 H2O(g)
A) Kp‘ =
B) Kp‘ =
C) Kp‘ =
D) Kp‘ =
19) What is true about the relationship of Kp and Kc for the reaction:
2 CH4(g) + 3 O2(g) ⇌ 2 CO(g) + 4 H2O(g)?
A) Kp < Kc
B) Kp = Kc
C) Kp > Kc
D) Kp and Kc are not related.
20) The oxidation of sulfur dioxide by oxygen to sulfur trioxide has been implicated as an
important step in the formation of acid rain: 2 SO2(g) + O2(g) ⇌ 2 SO3(g). If the equilibrium
partial pressures of SO2, O2, and SO3 are 0.564 atm, 0.102 atm, and 0.333 atm respectively at
1000 K, what is Kp at that temperature?
A) 0.292
B) 3.42
C) 5.79
D) 8.11
7
21) Given the reaction at a certain temperature: 2 HI(g) ⇌ H2(g) + I2(g). At equilibrium, the
partial pressure of HI is 1.8 × 10-3 atm, and the partial pressures for H2 and I2 are 0.10 atm each.
Find Kp at that temperature.
A) 3.2 × 10-4
B) 5.6 × 101
C) 3.1 × 103
D) 3.1 × 104
22) If Kc = 2.0 x 1033 at 25°C, for the following reaction: H2(g) + Cl2(g) ⇌ 2 HCl(g), then find
Kp at the same temperature.
A) 8.2 × 1031
B) 9.7 × 1032
C) 2.0 × 1033
D) 4.9 × 1034
23) Phosphorus pentachloride decomposes to phosphorus trichloride and chlorine gas at elevated
temperatures by the following reaction:
PCl5(g) ⇌ PCl3(g) + Cl2(g). If Kc = 1.8 at 250°C, what is the value of Kp at the same
temperature?
A) 4.2 × 10-2
B) 8.8 × 10-2
C) 65
D) 77
24) The decomposition of ammonia is: 2 NH3(g) = N2(g) + 3 H2(g). If Kp is 1.5 × 103 at 400°C,
what is the partial pressure of ammonia at equilibrium when N2 is 0.10 atm and H2 is 0.15 atm?
A) 2.2 × 10-7 atm
B) 4.7 × 10-4 atm
C) 2.1 × 103 atm
D) 4.4 × 106 atm
8
25) The decomposition of ammonia is: 2 NH3(g) ⇌ N2(g) + 3 H2(g). If the partial pressure of
ammonia is 1.6 × 10-3 atm and the partial pressures of N2 and H2 are each 0.25 atm at
equilibrium, what is the value for Kc at 400°C for the forward reaction?
A) 0.50
B) 1.4
C) 1.5 × 103
D) 4.6 × 106
26) The decomposition of ammonia is: 2 NH3(g) ⇌ N2(g) + 3 H2(g). If the pressure of ammonia
is 1.0 × 10-3 atm, and the pressures of N2 and H2 are each 0.20 atm, what is the value for Kp‘ at
400°C for the reverse reaction?
A) -6.2 × 10-4
B) -1.6 × 103
C) 6.2 × 10-4
D) 1.6 × 103
27) A 1.50 L vessel contains an equilibrium mixture of 0.100 mol of NO, 0.150 mol of Br2, and
0.250 mol of NOBr at 25°C. What is the value of Kp for the reaction below?
2 NO(g) + Br2(g) ⇌ 2 NOBr(g)?
A) 2.56
B) 62.5
C) 1.28 × 102
D) 1.53 × 103
28) As a rule, which of the following phases are not included in the equilibrium constant
expression?
I. pure liquids II. pure solids III. aqueous solutions IV. gases
A) I, II
B) I, IV
C) III, IV
D) II, III
29) Which equilibrium below is homogeneous?
A) BaSO4(s) ⇌ Ba2+(aq) + SO42-(aq)
B) 2 H2O2(l) ⇌ 2 H2O(l) + O2(g)
C) NH4NO3(s) ⇌ N2O(g) + 2 H2O(g)
D) 2 CO(g) + O2(g) ⇌ 2 CO2(g)
30) What is the equilibrium equation for the dissociation of formic acid in water?
HCOOH (aq) + H2O (l) ⇌ H3O+ (aq) + HCOO– (aq)
A) Kc =
B) Kc =
C) Kc =
D) Kc =
31) What is the equilibrium equation for the following reaction?
C2H4 (g) + 3 O2 (g) ⇌ 2 CO2 (g) + 2 H2O (l)
A) Kp =
B) Kp =
C) Kp =
D) Kp =
32) What is the equilibrium equation for the following reaction?
FeS(s) + 2 H3O+ (aq) ⇌ Fe2+(aq) + H2S (aq) + 2 H2O (l)
A) Kc =
B) Kc =
C) Kc =
D) Kc =
33) What is the equilibrium equation for the following reaction?
2 H2O (l) ⇌ H3O+ (aq) + OH– (aq)
A) Kc =
B) Kc =
C) Kc =
D) Kc = [H3O+] [OH–]
34) What is the value for Kc for the following reaction:
PbCl2(s) ⇌ Pb2+(aq) + 2 Cl–(aq), if PbCl2(s) = 1.50 grams, [Pb2+] = 1.6 × 10-2 M and [Cl–] =
3.2 × 10-2 M at equilibrium? (The molar mass of PbCl2(s) is 278 g/mol and its density is 5.85
g/cm3.)
A) 7.6 × 10-7
B) 1.6 × 10-5
C) 6.2 × 104
D) 1.3 × 106
11
35) What is the equilibrium constant, Kc, for the reaction: 2 Hg(l) + O2(g) ⇌ 2 HgO(s) if the
amounts of reactants and products at equilibrium are: 1.00 g of HgO(s), 2.00 mL of Hg(l), and
1.60 M O2(g)? (The molar mass and density of HgO(s) is 217 g/mol, and 1.10 g/cm3. The molar
mass and density of Hg(l) is 201 g/mol, and 13.6 g/mL.)
A) 6.85 × 10-4
B) 4.66 × 10-2
C) 0.625
D) 1.46 × 103
36) For which one of the following reactions will Kc = Kp?
A) CO(g) + 2 H2(g) ⇌ CH3OH(g)
B) ZnO(s) + CO(g) ⇌ Zn(s) + CO2(g)
C) 2 O3(g) ⇌ 3 O2(g)
D) COCl2(g) ⇌ CO(g) + Cl2(g)
37) If Kc = 0.900, and Kp = 538 for a hypothetical reaction, which of the equations below could
represent the reaction at 25°C?
A) A(g) + B(s) ⇌ 3 C(g)
B) A(l) + 2 B(g) ⇌ 2 C(g)
C) B(g) ⇌ C(l) + D(l)
D) A(g) ⇌ 2 C(s) + D(g)
38) Given the hypothetical reaction: 2 A(s) + x B(g) ⇌ 3 C(g), Kp = 0.0105 and Kc = 0.45 at
250°C. What is the value of the coefficient x?
A) 1
B) 2
C) 3
D) 4
39) For the reaction, A(g) + 2 B(g) ⇌ 2 C(g), Kc = 1 × 10-10 at 25°C. Which of the following
statements is true?
A) Δn = +1
B) The concentration of the products is greater than the concentration of the reactants.
C) The reaction is favored in the reverse direction.
D) The value of Kp will be larger than the value for Kc.
40) Which statement is true for a reaction with Kc equal to 2.43 × 10-12?
A) Increasing the temperature will not change the value of Kc.
B) There are appreciable concentrations of both reactants and products.
C) The reaction proceeds hardly at all towards completion.
D) The reaction proceeds nearly all the way to completion.
41) For the reaction: 4 HCl(g) + O2(g) ⇌ 2 Cl2(g) + 2 H2O(l), the equilibrium constant is 0.063
at 400 K. If the reaction quotient is 0.100, which of the following statements is not correct?
A) [HCl] will increase.
B) [O2] will increase.
C) [Cl2] will decrease.
D) [H2O] will increase.
42) The equilibrium constant is equal to 5.00 at 1300 K for the reaction:
2 SO2(g) + O2(g) ⇌ 2 SO3(g).
If initial concentrations are [SO2] = 1.20 M, [O2] = 0.45 M, and [SO3] = 1.80 M, the system is
A) at equilibrium.
B) not at equilibrium and will remain in an unequilibrated state.
C) not at equilibrium and will shift to the left to achieve an equilibrium state.
D) not at equilibrium and will shift to the right to achieve an equilibrium state.
43) The equilibrium constant, Kp, equals 3.40 at 25°C for the isomerization reaction:
cis-2-butene ⇌ trans-2-butene.
If a flask initially contains 1.00 atm of each gas, in what direction will the system shift to reach
equilibrium?
A) It will shift left.
B) It will shift right.
C) The system is already at equilibrium.
D) The system is not at equilibrium and will remain in an unequilibrated state.
44) Cyclohexane (C6H12) undergoes a molecular rearrangement in the presence of AlCl3 to
form methylcyclopentane (MCP) according to the equation:
C6H12 ⇌ MCP
If Kc = 0.143 at 25°C for this reaction, predict the direction the reaction will shift if the initial
concentrations of C6H12 and MCP are 0.200 M and 0.100 M, respectively. The system
A) will shift left.
B) will shift right.
C) is already at equilibrium.
D) is not at equilibrium and will remain in an unequilibrated state.
45) At a certain temperature, bromine and nitric oxide react to form nitrosyl bromide:
Br2(g) + 2 NO(g) ⇌ 2 NOBr(g).
When initial amounts of Br2, NO, and NOBr are mixed, the concentration of NOBr increases.
Which statement below is true?
A) Kc < Q
B) Kc > Q
C) Kc = Q
D) More information is needed to make a statement about Kc.
46) At a certain temperature, bromine and nitric oxide react to form nitrosyl bromide:
Br2(g) + 2 NO(g) ⇌ 2 NOBr(g). When 0.010 mol Br2 is mixed with 0.025 mol NO and 0.015
mol NOBr in a 2.50 L flask, the concentration of NOBr decreases. Which statement below is
true?
A) Kc < 36
B) Kc > 36
C) Kc < 90
D) Kc > 90
47) An equilibrium mixture of CO, O2 and CO2 at a certain temperature contains 0.0010 M CO2
and 0.0015 M O2. At this temperature, Kc, equals 1.4 × 102 for the reaction:
2 CO(g) + O2(g) ⇌ 2 CO2(g).
What is the equilibrium concentration of CO?
A) 4.8 × 10-6 M
B) 2.2 × 10-3 M
C) 9.3 × 10-2 M
D) 3.1 × 10-1 M
48) At a certain temperature, Kc equals 1.4 × 102 for the reaction:
2 CO(g) + O2(g) ⇌ 2 CO2(g).
If a 2.50-L flask contains 0.400 mol of CO2 and 0.100 mol of O2 at equilibrium, how many
moles of CO are also present in the flask?
A) 0.422 mol
B) 0.169 mol
C) 0.107 mol
D) 0.0114 mol
49) For the isomerization reaction:
butane ⇌ isobutane
Kp equals 25 at 500°C. If the initial pressures of butane and isobutane are 10. atm and 0.0 atm,
respectively, what are the pressures of the two gases at equilibrium?
A) P(butane) = 0.38 atm and P(isobutane) = 9.6 atm
B) P(butane) = 0.40 atm and P(isobutane) = 10. atm
C) P(butane) = 9.6 atm and P(isobutane) = 0.38 atm
D) P(butane) = 10 atm and P(isobutane) = 0.40 atm
50) The following two isomers of C3H7NO exist in equilibrium with each other in solution:
If Kc = 0.57 at 25°C and the initial concentration of the reactant is 0.50 M and the product is 0.70
M, what are the concentrations at equilibrium?
A) [reactant] = 0.43 M and [product] = 0.24 M
B) [reactant] = 0.67 M and [product] = 0.38 M
C) [reactant] = 0.76 M and [product] = 0.44 M
D) [reactant] = 0.82 M and [product] = 0.47 M
51) Cyclohexane (C6H12) undergoes a molecular rearrangement in the presence of AlCl3 to
form methylcyclopentane (CH3C5H9) according to the equation:
C6H12 ⇌ CH3C5H9
If Kc = 0.143 at 25°C for this reaction, find the equilibrium concentrations of C6H12 and
CH3C5H9 if the initial concentrations are 0.200 M and 0.100 M, respectively.
A) [C6H12] = 0.0625 and [CH3C5H9] = 0.062 M
B) [C6H12] = 0.138 and [CH3C5H9] = 0.162 M
C) [C6H12] = 0.262 M and [CH3C5H9] = 0.038 M
D) [C6H12] = 0.282 and [CH3C5H9] = 0.018 M
52) At a certain temperature the equilibrium constant, Kc, equals 0.11 for the reaction:
2 ICl(g) ⇌ I2(g) + Cl2(g).
What is the equilibrium concentration of ICl if 0.75 mol of I2 and 0.75 mol of Cl2 are initially
mixed in a 2.0-L flask?
A) 0.23 M
B) 0.28 M
C) 0.45 M
D) 0.56
53) The equilibrium constant, Kp, equals 3.40 for the isomerization reaction:
cis-2-butene ⇌ trans-2-butene.
If a flask initially contains 0.250 atm of cis-2-butene and 0.125 atm of trans-2-butene, what is
the equilibrium pressure of each gas?
A) P(cis-2-butene) = 0.037 atm, P(trans-2-butene) = 0.125 atm
B) P(cis-2-butene) = 0.048 atm, P(trans-2-butene) = 0.165 atm
C) P(cis-2-butene) = 0.074 atm, P(trans-2-butene) = 0.250 atm
D) P(cis-2-butene) = 0.085 atm, P(trans-2-butene) = 0.290 atm
54) Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures
according to the reaction:
At 250°C, 0.250 M PCl5 is added to a flask. If Kc = 1.80, what are the equilibrium
concentrations of each gas?
A) [PCl5] = 0.0280 M, [PCl3] = 0.222 M, [Cl2] = 0.222 M
B) [PCl5] = 1.25 M, [PCl3] = 0.474 M, [Cl2] = 0.474 M
C) [PCl5] = 1.80 M, [PCl3] = 1.80 M, [Cl2] = 1.80 M
D) [PCl5] = 2.27 M, [PCl3] = 2.02 M, [Cl2] = 2.02 M
55) The esterification of acetic acid and ethanol is given by the reaction below:
C2H5OH(aq) + CH3COOH(aq) ⇌ CH3COOC2H5(aq) + H2O(l)
When 1.00 mol of ethanol was mixed with 2.00 mol of acid in a 1.00 L flask, 0.86 mol of ester
was formed at room temperature. What is the value of the equilibrium constant, Kc?
A) 0.43
B) 2.3
C) 4.6
D) 5.4
56) Kp is equal to 48.70 at 731 K for the reaction: H2(g) + I2(g) ⇌ 2 HI(g). Initially the mixture
contains 0.08592 atm each of H2 and I2 and 1.0000 atm of HI. What is the pressure of HI at
equilibrium?
A) 0.7955 atm
B) 0.9108 atm
C) 0.9140 atm
D) 0.9498 atm
57) When baking soda is heated it decomposes according to the following reaction:
2 NaHCO3(s) ⇌ Na2CO3(s) + H2O(g) + CO2(g)
If sufficient baking soda is placed in a container and heated to 90°C, the total pressure of the
gases is 0.5451 atm. What is the value of Kp at that temperature?
A) 0.07428
B) 0.2973
C) 0.4228
D) 1.091
58) Ammonium carbamate can dissociate into gases at 25°C according to the reaction:
NH2COONH4(s) ⇌ 2 NH3(g) + CO2(g)
If sufficient ammonium carbamate is sealed in a flask, the total pressure will be 0.117 atm at
equilibrium. What is the value of Kp at 25°C?
A) 2.37 × 10-4
B) 2.00 × 10-4
C) 1.60 × 10-3
D) 3.42 × 10-1
59) Gaseous hydrogen bromide decomposes at elevated temperatures according to the following
equation: . At a certain temperature a 2.00 L flask is initially filled only
with 0.600 mol of HBr. What is the value of Kc at that temperature if the flask contains 0.104
mol of H2 at equilibrium?
A) 7.04 × 10-2
B) 4.40 × 10-2
C) 3.00 × 10-2
D) 2.10 × 10-1
60) When reaction (1) and (2) below are added together, the result is reaction (3).
1) H2O(l) + HNO2(aq) ⇌ H3O+(aq) + NO2–(aq)
2) H3O+(aq) + OH–(aq) ⇌ 2 H2O(l)
3) HNO2(aq) + OH–(aq) ⇌ NO2–(aq) + H2O(l)
If K1 = 4.50 × 10-4, and K2 = 1.00 × 1014, find the equilibrium constant, K3.
A) 4.50 × 10-18
B) 4.50 × 1010
C) 1.00 × 1014
D) 2.22 × 1017
61) Oxalic acid can donate two protons to water in successive reactions:
(1) H2C2O4(aq) + H2O(l) ⇌ H3O+(aq) + HC2O4–(aq)
(2) HC2O4–(aq) + H2O(l) ⇌ H3O+(aq) + C2O42-(aq)
If Kc1 = 5.9 × 10-2 and Kc2 = 6.4 × 10-5 at 25°C, what is the value of Kc for reaction (3)?
(3) H2C2O4(aq) + 2 H2O(l) ⇌ 2 H3O+(aq) + C2O42-(aq)
A) 3.8 × 10-6
B) 1.1 × 10-3
C) 5.9 × 10-2
D) 9.2 × 102
62) Acids donate protons to water according to the general equation:
HA(aq) + H2O(l) ⇌ H3O+(aq) + A–(aq)
Consider the following acids and their equilibrium constants for reaction with water at 25°C. If
all the acids have the same initial concentration, which is the strongest acid (i.e. which donates
the most protons to water)?
A) HBrO, Kc = 2.0 × 10-9
B) HNO2, Kc = 4.5 × 10-4
C) HF, Kc = 3.5 × 10-4
D) HIO3, Kc = 1.7 × 10-1
63) For acid solutions of the same molarity acid strength is proportional to the equilibrium
concentration of H3O+. For equimolar solutions of acids, which equilibrium expression below
corresponds to the strongest acid?
A) Kc = = 3.5 × 10–4
B) Kc = = 3.5 × 10–8
C) Kc = = 4.5 × 10–4
D) Kc = = 4.9 × 10–10
20
64) The equilibrium constant Kc for the reaction HF(aq) + H2O(l) ⇌ H3O+(aq) +F–(aq) is 3.5 ×
10-4. What is the equilibrium concentration of H3O+ if the initial concentration of HF is 1.0 M?
A) 1.0 M
B) 3.5 × 10–2 M
C) 1.9 × 10–2 M
D) 1.9 × 10-4 M
65) The solubility of 1:1 salts is measured by the equilibrium constant for the general reaction:
MX(s) = Mn+(aq) + Xn-(aq). Given the following salts and their equilibrium constants for the
reaction above at 25°C, which salt is the least soluble?
A) MgCO3, Kc = 6.8 × 10-6
B) CaCO3, Kc = 5.0 × 10-9
C) SrCO3, Kc = 5.6 × 10-10
D) BaCO3, Kc = 2.6 × 10-9
66) Salt solubilities can be compared by the concentration of cation formed when the salt
dissolves in the general reaction: MaXb(s) ⇌ a Mb+(aq) + b Xa-(aq). Given the following salts
and their equilibrium constants for the reaction above at 25°C, which salt is the least soluble?
A) AgCl, Kc = 1.8 × 10-10
B) Ag2SO4, Kc = 1.2 × 10-5
C) CaCO3, Kc = 2.6 × 10-9
D) CaF2, Kc = 1.5 × 10–10
67) “If a stress is applied to a reaction mixture at equilibrium, the reaction occurs in the direction
that will relieve the stress.” This statement is called
A) the First Law of Thermodynamics.
B) the Law of Combining Volumes.
C) the Law of Mass Action.
D) Le Châtelier’s principle.
68) Which of the following changes in reaction conditions will alter the composition of an