General, Organic, and Biological Chemistry, 3e (Timberlake)
Chapter 6 Chemical Reactions and Quantities
6.1 Multiple-Choice Questions
1) A chemical equation is balanced when
A) the total number of molecules is the same in reactants and products.
B) the total number of ions is the same in reactants and products.
C) the sum of the coefficients of the reactants is equal to the sum of the coefficients of the
products.
D) the number of atoms of each element is the same in reactants and products.
E) the charge on each atom is the same in reactants and products.
2) Which of the following gives the balanced equation for this reaction?
K3PO4 + Ca(NO3)2 → Ca3(PO4)2 + KNO3
A) KPO4 + CaNO3 + KNO3
B) K3PO4 + Ca(NO3)2 → Ca3(PO4)2 + 3KNO3
C) 2 K3PO4 + Ca(NO3)2 → Ca3(PO4)2 + 6KNO3
D) 2 K3PO4 + 3Ca(NO3)2 → Ca3(PO4)2 + 6KNO3
E) K3PO4 + Ca(NO3)2 → Ca3(PO4)2 + KNO3
3) Which of the following correctly gives the best coefficients for the reaction below?
N2H4 + H2O2 → N2 + H2O
A)
B)
C)
D)
E)
1, 1, 1 ,1
1, 2, 1, 4
2, 4, 2, 8
1, 4, 1, 4
2, 4, 2, 4
4) What coefficient is placed in front of O2 to complete the balancing of the following equation?
C5H8 + ? O2 → 5CO2 + 4 H2O
A)
B)
C)
D)
E)
1
3
5
7
9
1
5) What is the coefficient of hydrogen, H2, when the following equation is balanced?
Al + H2SO4 → Al2(SO2)3 + ? H2
A)
B)
C)
D)
E)
1
2
3
4
5
Pentane (C5H12) reacts with oxygen (O2) to form carbon dioxide (CO2) and water (H2O) according to the
following reaction. Answer the question(s) that follow about this reaction.
C5H12 + ? O2 → ? CO2 + ? H2O
6) What is the coefficient for oxygen in the balanced equation?
A) 2
B) 4
C) 5
D) 6
E) 8
7) What is the coefficient for carbon dioxide in the balanced equation?
A) 2
B) 4
C) 5
D) 6
E) 8
8) What is the coefficient for water in the balanced equation?
A) 2
B) 4
C) 5
D) 6
E) 8
9) In a __________ reaction, two or more elements or compounds form one product.
A) decomposition
B) single replacement
C) dehydration
D) double replacement
E) combination
2
10) The following reaction takes place when an electric current is passed through water. It is an
example of a __________ reaction.
2 H2O → 2H2 + O2
A)
B)
C)
D)
E)
combination
single replacement
dehydration
decomposition
double replacement
11) Which of the following is an oxidation-reduction reaction?
A) CaCl2 + Na2SO4 → CaSO4 + 2NaCl
B) KOH + HNO3 → H2O + KNO3
C) N2 + O2 → 2NO
D) AgNO3 + NaCl → AgCl + NaNO3
E) Al2(SO4)3 + 6KOH → 2Al(OH)3 + 3K2SO4
12) What is oxidized and what is reduced in the following reaction?
2Al(s) + 3Br2 (g) → 2AlBr3 (s)
A) Al is oxidized and Br2 is reduced.
B) AlBr3 is reduced and Br2 is oxidized.
C) Al is reduced and Br2 is oxidized.
D) AlBr3 is reduced and Al is oxidized.
E) AlBr3 is oxidized and Al is reduced.
13) Which of the following describes an oxidation?
A) loss of electrons or loss of oxygen
B) loss of electrons or gain of oxygen
C) loss of electrons or gain of hydrogen
D) gain of electrons or gain of oxygen
E) gain of electrons or loss of H
14) In an oxidation-reduction reaction, the substance oxidized always
A) takes on oxygen atoms.
B) shows a loss of electrons.
C) gives up hydrogen atoms.
D) shows a gain of electrons.
E) becomes a charged species.
3
15) In this reaction, what is the substance oxidized?
Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g)
A)
B)
C)
D)
E)
chlorine
zinc chloride
hydrogen
Zn
oxygen
16) In an oxidation-reduction reaction, the substance reduced always
A) takes on oxygen atoms.
B) shows a loss of electrons.
C) gives up hydrogen atoms.
D) shows a gain of electrons.
E) becomes a charged species.
17) In this reaction, what is the coefficient for calcium oxide?
CaO(s) + CO2(g) → CaCO3(s)
A)
B)
C)
D)
E)
1
2
3
4
5
18) In this reaction, what is the correct coefficient for sodium chloride?
Pb(NO3)2 (aq) + NaCl(aq) → PbCl2 (s) + NaNO3 (aq)
A)
B)
C)
D)
E)
1
2
3
4
5
19) In the following reaction, what is the correct coefficient for aluminum chloride?
Al(s) + Cl2 (g) → AlCl3 (s)
A)
B)
C)
D)
E)
1
2
3
4
5
4
20) What is the classification for this reaction?
SO3 (g) + H2O (l) → H2SO4 (l)
A)
B)
C)
D)
E)
decomposition
combination
replacement
double replacement
oxidation reduction
21) The reaction of carbon with oxygen to produce carbon monoxide is an example of which
class of reaction?
2C(s) + O2 (g) → 2CO(g)
A)
B)
C)
D)
E)
single replacement
double replacement
combination
catalytic
endothermic
22) For the following reaction, what is the correct coefficient for the H2?
Fe(s) + HCl(aq) → FeCl3 (aq) + H2 (g)
A) 1
B) 2
C) 3
D) 4
E) 5
23) What is the classification for this unbalanced reaction?
Fe + HCl → FeCl3 + H2
A) dehydration
B) combination
C) decomposition
D) single replacement
E) double replacement
24) In any balanced chemical equation, the number of each type of atom on both sides of the
equation is
A) doubled.
B) the same.
C) decreased by one.
D) increased by one.
E) dependent on the temperature.
5
25) How many molecules of water, H2O, are present in 75.0 g of H2O?
A) 75.0 molecules
B) 4.17 molecules
C) 7.53 x 1024 molecules
D) 2.51 x 1024 molecules
E) 5.02 x 1024 molecules
26) How many hydrogen atoms are present in 75.0 of g H2O?
A) 75.0 atoms
B) 4.17 atoms
C) 7.53 x 1024 atoms
D) 2.51 x 1024 atoms
E) 5.02 x 1024 atoms
27) How many moles of water, H2O, are present in 75.0 g of H2O?
A)
B)
C)
D)
E)
4.41 moles
4.17 moles
75.0 moles
7.50 moles
1.35 x 103 moles
28) How many moles of iron are present in 3.15 x 1024 atoms of iron?
A) 5.23 moles
B) 1.90 moles
C) 292 moles
D) 0.523 moles
E) 1.90 x 1048 moles
29) One mole of particles of any substance contains how many particles?
A) 106
B) 3 x 10-10
C) 3 x 1010
D) 6.02 x 1023
E) 6.02 x 10-23
30) Avogadro's number is the number of
A) particles in 1 mole of a substance.
B) amu in 1 mole of a substance.
C) grams in 1 mole of a substance.
D) moles in 6.02 x 1023 grams of an element.
E) moles in 6.02 x 1023 amu of an element.
6
31) The molar mass of potassium is
A) 19 g.
B) 31.0 g.
C) 6.02 x 1023 grams.
D) 39.1 g.
E) 15g.
32) One mole of helium gas weighs
A) 1.00 g.
B) 2.00 g.
C) 3.00 g.
D) 4.00 g.
E) 8.00 g.
33) 0.100 mole of lithium weighs
A) 3.00 g.
B) 0.300 g.
C) 6.94 g.
D) 0.694 g.
E) 0.700 g.
34) Calculate the molar mass of potassium chloride, KCl.
A) 74.6 g
B) 54.5 g
C) 6.74 g
D) 67.4 g
E) 19.0 g
35) What is the molar mass of copper(II) sulfate, CuSO4?
A)
B)
C)
D)
E)
16.0 g
63.6 g
111.6 g
159.6 g
319.2 g
36) Calculate the molar mass of magnesium chloride, MgCl2.
A)
B)
C)
D)
E)
24.3 g
95.2 g
125.9 g
59.8 g
70.0 g
7
37) What is the molar mass of sodium phosphate, Na3PO4?
A)
B)
C)
D)
E)
119.0 g
308.0 g
164.0 g
226.0 g
354.0 g
38) How many moles of carbon atoms are there in 0.500 mole of C2H6?
A)
B)
C)
D)
0.500 moles
1.00 moles
3.00 moles
6.02 x 1023 moles
E) 4.00 moles
39) What is the molar mass of sucrose (C12H22O11)?
A)
B)
C)
D)
E)
29.0 g
50.2 g
210 g
342 g
182 g
40) One mole of neon atoms has a mass of
A) 6.02 x 1023 grams.
B)
C)
D)
E)
14.0 g.
10.0 g.
20.2 g.
30.2 g.
41) The molar mass of C3H8O2 is
A)
B)
C)
D)
E)
76.0 g.
60.0 g.
29.0 g.
69.0 g.
52.0 g.
42) The molar mass of calcium hydroxide, Ca(OH)2, is
A)
B)
C)
D)
E)
58.1 g.
57.1 g.
74.1 g.
114.2 g.
38.0 g.
8
43) What is the molar mass of Mg3(PO4)2, a substance formerly used in medicine as an antacid?
A)
B)
C)
D)
E)
71.3 g
118.3 g
150.3 g
214.3 g
262.9 g
44) 4.00 moles of sodium have a mass of
A) 4.60 g.
B) 11.0 g.
C) 23.0 g.
D) 44.0 g.
E) 92.0 g.
45) How many moles of K2SO4 are in 15.0 g of K2SO4?
A) 0.172 moles
B) 2.61 x 103 moles
C) 0.111 moles
D) 0.0861 moles
E) 0.119 moles
46) 3.00 moles of NO2 have a mass of
A)
B)
C)
D)
E)
138 g.
46.0 g.
30.0 g.
90.0 g.
45.0 g.
47) How many grams of Fe2O3 are there in 0.500 mole of Fe2O3?
A)
B)
C)
D)
E)
79.8 g
35.9 g
63.8 g
51.9 g
160. g
48) How many grams of glucose (C6H12O6) are in 3.55 moles of glucose?
A)
B)
C)
D)
E)
180. g
639 g
103 g
426 g
50.7 g
9
49) Given the following equation, what is the correct form of the conversion factor needed to
convert the number of moles of O2 to the number of moles of Fe2O3 produced?
4Fe(s) + 3O2 (g) → 2Fe2O3 (s)
A)
B)
C)
D)
E)
For the question(s) that follow, consider the following equation.
2Mg + O2 → 2MgO
50) The number of moles of oxygen gas needed to react with 4.0 moles of Mg is
A) 1.0 mole.
B) 2.0 moles.
C) 3.0 moles.
D) 4.0 moles.
E) 6.0 moles.
51) The number of moles of MgO produced when 0.20 mole of O2 reacts completely is
A)
B)
C)
D)
E)
0.10 mole.
0.20 mole.
0.40 mole.
0.60 mole.
0.80 mole.
52) How many moles of magnesium are needed to react with 16 g of O2?
A)
B)
C)
D)
E)
0.50 mole
1.0 moles
2.0 moles
3.0 moles
4.0 moles
10
53) How many grams of MgO are produced when 40.0 grams of O2 react completely with Mg?
A)
B)
C)
D)
E)
30.4 g
50.4 g
60.8 g
101 g
201 g
For the question(s) that follow, consider the following balanced equation.
Mg3N2 (s) + 6H2O(l) → 3 Mg(OH)2 (s) + 2NH3 (g)
54) What is the correct form of the conversion factor needed to convert the number of moles of
H2O to the number of moles of NH3 produced?
A)
B)
C)
D)
E)
55) When 2 moles of Mg3N2 are allowed to react, how many moles of H2O also react?
A)
B)
C)
D)
E)
1 mole
4 moles
6 moles
8 moles
12 moles
56) When 2.00 moles of H2O react, how many grams of NH3 are produced?
A)
B)
C)
D)
E)
34.0 g
10.0 g
5.67 g
11.3 g
102 g
11
57) How many grams of H2O are needed to produce 150 g of Mg(OH)2?
A)
B)
C)
D)
E)
46 g
18 g
130 g
93 g
23 g
58) When 4 moles of aluminum are allowed to react with an excess of chlorine gas, Cl2, how
many moles of aluminum chloride are produced?
A) 1 mole
B) 2 moles
C) 3 moles
D) 4 moles
E) 5 moles
59) In the reaction of nitrogen gas, N2, with hydrogen gas, H2, to form ammonia gas, NH3 , how
many moles of hydrogen are needed to react with two moles of nitrogen?
A) 2 moles
B) 4 moles
C) 6 moles
D) 8 moles
E) 10 moles
60) How many grams of hydrogen are needed to produce 1.80 g of water according to this
equation?
2H2 + O2 → 2H2O
A)
B)
C)
D)
E)
0.100 g
0.180 g
0.200 g
2.00 g
4.00 g
61) In the reaction of silver nitrate with sodium chloride, how many grams of silver chloride will
be produced from 100. g of silver nitrate when it is mixed with an excess of sodium chloride?
The equation for the reaction is below.
AgNO3 (aq) + NaCl(aq) → AgCl(s) + NaNO3 (aq)
A)
B)
C)
D)
E)
107.9 g
169.9 g
84.4 g
0.589 g
58.9 g
12
62) Find the mass of AlCl3 that is produced when 25.0 grams of Al2O3 react with HCl according
to the following equation.
Al2O3 (s) + 6HCl(aq) → 2AlCl3 (aq) + 3H2O(l)
A)
B)
C)
D)
E)
155 g
72.9 g
65.4 g
32.6 g
16.3 g
63) How many grams of NO are required to produce 145 g of N2 in the following reaction?
4NH3 (g) + 6NO(g) → 5N2 (g) + 6 H2O(l)
A)
B)
C)
D)
E)
186 g
155 g
125 g
129 g
145 g
64) The _____ is the minimum energy needed for a chemical reaction to begin.
A) reaction energy
B) activation energy
C) energy of reactants
D) energy of products
E) heat of reaction
65) How many grams of CO2 are produced from 125 g of O2 and excess CH4?
CH4 + 2 O2 → CO2 + 2H2O
A) 125 g of CO2
B) 62.5 g of CO2
C) 172 g of CO2
D) 85.9 g of CO2
E) 250. g of CO2
13
66) When 3.05 moles of CH4 are mixed with 5.03 moles of O2 the limiting reactant is __________.
CH4 + 2 O2 → CO2 + 2H2O
A) CH4
B) O2
C) CO2
D) H2O
67) A reaction that releases energy as it occurs is classified as a(n) __________.
A) endothermic reaction
B) exothermic reaction
C) oxidation-reduction reaction
D) catalyzed reaction
E) decomposition reaction
68) When 85.0 g of CH4 are mixed with 160. g of O2 the limiting reactant is __________.
CH4 + 2O2 → CO2 + 2 H2O
A) CH4
B) O2
C) CO2
D) H2O
69) When 85.0 g of CH4 are mixed with 160. g of O2 what is the maximum amount of CO2 that
can be produced?
CH4 + 2O2 → CO2 + 2H2O
A) 2.50 moles
B) 5.00 moles
C) 5.31 moles
D) 7.81 moles
70) What type of reaction is: CH4 + 2O2 → CO2 + 2H2O + 218 kcal?
A)
B)
C)
D)
E)
an endothermic reaction
an exothermic reaction
a single replacement reaction
a combination reaction
a decomposition reaction
14
71) How many kcal are produced when 32.0 g of CH4 react?
CH4 + 2O2 → CO2 + 2H2O + 218 kcal
A) 218 kcal
B) 109 kcal
C) 436 kcal
D) 6.81 kcal
E) 698 kcal
72) For the reaction: 2H2O(l) + 137 kcal → 2H2 (g) + O2 (g)
how many kcal are needed to form 2.00 moles O2 (g)?
A)
B)
C)
D)
E)
68.5 kcal
137 kcal
274 kcal
190. kcal
548 kcal
73) For the reaction: 2H2O(l) + 137 kcal → 2H2 (g) + O2 (g)
how many kcal are needed to react 50.0 g H2O(l)?
A)
B)
C)
D)
E)
380. kcal
137 kcal
274 kcal
190. kcal
760. kcal
74) If the reaction shown below is exothermic, the energy level of the reactants is __________.
H2 + O2 → 2H2O
A)
B)
C)
D)
E)
lower than that of the products
higher than that of the products
the same as that of the products
possibly lower, possibly higher than that of the products
higher than the activation energy of the reaction
75) In an endothermic reaction,
A) heat flows out of the system.
B) energy is absorbed by the system.
C) the temperature of the system increases.
D) the products have less energy that the reactants.
E) the products have the same energy that the reactants.
15
76) Any reaction that absorbs 150 kcal of energy can be classified as __________.
A) endothermic
B) exothermic
C) activated
D) reduction
E) oxidation
77) The __________ is the energy difference between reactants and products in a chemical
reaction.
A) transition energy
B) activation energy
C) product energy
D) overall energy
E) heat of reaction
78) Find the mass of AlCl3 that is produced when 10.0 grams of Al2O3 react with 10.0 g of HCl
according to the following equation.
Al2O3 (s) + 6HCl(aq) → 2 AlCl3 (aq) + 3 H2O(aq)
A)
B)
C)
D)
E)
16.2 g
20.0 g
12.2 g
10.0 g
6.10 g
79) When 10.0 g of NH3 reacts, the actual yield of N2 is 8.50 g. What is the percent yield?
4 NH3 (g) + 6NO(g) → 5N2 (g) + 6 H2O(l)
A)
B)
C)
D)
E)
85.0%
51.5%
20.6%
41.3%
8.5%
16
6.2 Bimodal Questions
1) In this reaction, what is the correct coefficient for hydrogen gas?
? H2 + ? O2 → ? H2O
A)
B)
C)
D)
E)
1
2
3
4
5
Barium chloride and sodium sulfate react according to the following equation.
BaCl2 + Na2SO4 → BaSO4 + 2NaCl
Answer the question(s) that follow about this reaction.
2) How many moles of barium sulfate are produced from 0.100 mole of barium chloride?
A) 0.0100 mole
B) 0.100 mole
C) 0.200 mole
D) 1.00 mole
E) 2.00 moles
3) How many grams of barium sulfate can be produced from 0.100 mole of barium chloride?
A) 1.37 g
B) 2.33 g
C) 23.3 g
D) 137 g
E) 233 g
4) How many grams of barium chloride are needed to make 100. grams of barium sulfate?
A) 44.9 g
B) 89.3 g
C) 208.3 g
D) 233.3 g
E) 46.6 g
17
Answer the question(s) that follow about the following reaction.
2 H2O2 → 2 H2O + O2
5) How many moles of oxygen gas can 30. g of hydrogen peroxide ( H 2O2) produce, if
decomposition is complete?
A) 0.50 mole
B) 0.88 mole
C) 1.0 mole
D) 2.0 mole
E) 0.44 mole
6) How many grams of water will 100. grams of hydrogen peroxide ( H 2O2 → H2 + O2)
produce?
A) 3600 g
B) 360. g
C) 5.88 g
D) 52.9 g
E) 106 g
7) How many grams of hydrogen peroxide are needed to produce 25.0 g of oxygen?
A) 106 g
B) 26.6 g
C) 5.88 g
D) 25.0 g
E) 53.1 g
8) How many grams of hydrogen peroxide ( H2O2) are needed to produce 5.0 moles of water?
A)
B)
C)
D)
E)
90. g
180 g
3060 g
306 g
170 g
6.3 Short Answer Questions
1) The number of particles in 1 mole of hydrogen gas is __________.
2) The molar mass of copper(II) nitrate, Cu(NO3)2 is __________.
3) What is the mass of 1 mole of argon gas?
4) What is the mass of 1 mole of helium gas?
18
5) Acetylene gas, C2H2, reacts with oxygen according to the following equation. If 2.00 moles
of acetylene react completely with sufficient oxygen, how many grams of carbon dioxide are
produced?
2 C2H2 + 5O2 → 4CO2 + 2H2O
6) What type of reaction is the following?
2KClO3 → 2KCl + 3O2
7) What type of reaction is the following?
Zn + 2HCl → ZnCl2 + H2
6.4 True/False Questions
1) The molar mass of silver is 47 g.
2) The molar mass of magnesium is 24.3 g.
3) The mass of one mole of water is 18.0 g
4) The molar mass of chlorine gas is 35.5 g.
5) The molar mass of copper(II) chloride is 134.6 g.
6) In the reaction of hydrogen gas with oxygen gas to produce water, 1 mole of oxygen gas can
produce 2 moles of water, given sufficient hydrogen available.
7) Avogadro's number is the number of grams in a mole.
8) The following is a decomposition reaction.
2KClO3 → 2KCl + 3O2
19
6.5 Matching Questions
Identify the energy associated with each of the labeled parts of the following diagram.
1) Region A
A) heat of reaction
2) Region B
B) energy of reactants
3) Region C
C) activation energy
4) Region D
D) energy of products
Identify the letter of the diagram corresponding to the given type of reaction.
A
B
5) endothermic reaction
A) Diagram B
6) exothermic reaction
B) Diagram A
20