• Ask students to suggest three or more everyday situations that are analogous to
synthesis reactions. Some examples are: students in a class forming groups to
work on a project, two companies merging to form a new company, or a baker
Chapter 6 Answers
combining ingredients to make a cake.
Answers to Practice Problems 6.1, p. 226
1. This is a synthesis reaction (between a metal and a non-metal).
The balanced chemical equation is: 2Li + Cl2 ĺ 2LiCl.
2.
This is a synthesis reaction (between a metal and a non-metal).
The balanced chemical equation is: 2Ca + O2 ĺ 2CaO.
3.
This is a synthesis reaction (between two non-metals). The
balanced chemical equation is: C(s) + O2(g) ĺ CO2(g).
Answers to Practice Problems 6.2, p. 227
1. This is a decomposition reaction (for an ionic compound). The
balanced chemical equation is: 8MgS ĺ 8Mg + S8.
2. This is a decomposition reaction (for an ionic compound). The
balanced chemical equation is: 2NaI ĺ 2Na + I2. Note that iodine
is diatomic; many students miss this fact. See Table 6.2, student
book page 225.
3. This is a decomposition reaction (for an ionic compound). The
balanced chemical equation is: 2NaCl(s) ĺ 2Na(s) + Cl2(g). Note
that chlorine is diatomic; many students miss this fact. See Table
6.2, student book page 225.
Unit B: Chemical Reactions
103
Chapter 6 Answers
nit B: Chemical Reactions
!"#$
Key Concept Review
1. Two types of chemical reactions discussed in this section are
synthesis reactions and decomposition reactions.
2. The products of a neutralization reaction are a salt (a compound
consisting of a positive metal ion or polyatomic ion and a non-metal
ion or polyatomic ion) and water.
3. (a) synthesis chemical reaction: A + B ĺ AB
(b) decomposition chemical reaction: AB ĺ A + B
(c) neutralization reaction: HB +XOH ĺ XB + H2O
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Connect Your Understanding
4. (a) decomposition
(b) decomposition
(c) synthesis
(d) synthesis
(e) decomposition
(f) decomposition
5. (a) This is a synthesis reaction because the reactants are both
elements and the product is a compound.
(b) Iron(II) is in the compound FeO.
(c) The form of iron involved in the chemical reaction is iron(II)
because the ion charge of the single oxygen atom in the
compound FeO is 2í. Since the each molecule of this compound
contains only a single atom of iron, it must be the iron(II) form.
6. (a) word equation: potassium chlorate ĺ potassium chloride +
oxygen
(b) skeleton equation: KClO3(s) ĺ KCl(s) + O2(g)
(c) balanced chemical equation: 2KClO3(s) ĺ 2KCl(s) + 3O2(g)
7. The decomposition reaction for water is 2H2O(l) ĺ 2H2(g) + O2(g).
8. word equation: zinc + nitrogen ĺ zinc nitride
skeleton equation: Zn(s) + N2(g) ĺ Zn3N2(s)
balanced chemical equation: 3Zn(s) + N2(g) ĺ Zn3N2(s)
9. word equation: magnesium + chlorine ĺ magnesium chloride
skeleton equation: Mg(s) + Cl2(g) ĺ MgCl2(s)
balanced chemical equation: Mg(s) + Cl2(g) ĺ MgCl2(s)
10. It is important to know about the chemical reaction for rusting
because it is common to use metals out of doors, where they are
exposed to oxygen gas in the air. Examples are automobile frames
and bodies, bicycles, railings, statues, and the steel used for
supporting roadways and buildings.
course, states are therefore not included in the answers.
• As students read section 6.2, you may wish to provide Literacy
Strategy Line Masters 2, 3, 4, and 8 to help them understand and record
Chapter
6 Answers
the content.
Answers to Practice Problems 6.3, p. 233
1. This is a single displacement reaction in which one metal
displaces the metal in an ionic compound.
Balanced equation: Mg + Zn(NO3)2 ĺ Mg(NO3)2 + Zn
2. This is a single displacement reaction in which one metal
displaces the metal in an ionic compound.
Balanced equation: Fe(s) + 2AgNO3(aq) ĺ Fe(NO3)2(aq) +
2Ag(s)
Answers to Practice Problems 6.4, p. 234
1. This is a single displacement reaction in which one non-metal
displaces the non-metal in an ionic compound.
Balanced equation: 3F2 + 2AlBr3 ĺ 3Br2+ 2AlF3
2. This is a single displacement reaction in which one non-metal
displaces the non-metal in an ionic compound.
Balanced equation: Cl2 + 2AgBr ĺ Br2+ 2AgCl
3. This is a single displacement reaction where one non-metal
displaces the non-metal in an ionic compound.
Balanced equation: 3Cl2(g) + 2NiBr3(aq) ĺ 2NiCl3(aq) +
3Br2(l)
Answers to Practice Problems 6.5, p. 235
1. This is a double displacement reaction.
Balanced equation:
AlCl3(aq) + 3NaOH (aq) ĺ Al(OH)3(s) + 3NaCl(aq)
2. This is a double displacement reaction.
Balanced equation: CuNO3(aq) + KBr(aq) ĺ CuBr(s) +
KNO3(aq)
Unit B: Chemical Reactions
113
Take It Further
Students are asked to prepare a classroom poster that displays and
describes how we use hydrocarbons to produce energy. Ask students to
first generate a mind map of hydrocarbon fuels. Examples are gasoline,
natural gas (methane), propane, jet fuel, diesel fuel, gasohol, and ethanol.
Ask students to then provide information about the ways in which we use
Chapter 6 Answers
B: Chemical Reactions
10. This is a single displacement reaction: Cl2(aq) + 2KBr(aq) ĺ
2KCl(aq) + Br2(aq).
11. (a) When the log burns, carbon dioxide gas and water vapour are
produced.
(b) No, the law of conservation of mass still holds, but the log burned
in an open system. The mass of the gases produced account for
the difference in mass between the log and the ashes.
12. (a) Mg + Zn(NO3)2 ĺ Zn + Mg(NO3)2
(b) F2 + CaBr2 ĺ Br2 + CaF2
(c) Li + KClO3 ĺ K + LiClO3
Reflection
13. Student answers will vary, but they might include the surprising
colour changes they observed in Quick Lab B22, the formation of
copper on the nail in Design a Lab Activity B25 Iron and Copper(II)
Chloride, or the beautiful silver and copper crystals they observed in
Inquiry Activity B26 Single Displacement Reactions. Students might
suggest that they are surprised that there are only six different types
of chemical reactions.
Reteaching Strategy
Ask students to compose their own multiple choice questions for the
content of this section. Each question should have four (A, B, C, D)
choices. Students can prepare a separate answer key. This strategy works
well for review prior to a section, chapter, or unit test.
ESL/ELL Strategy
To help students understand the various types of reactions, you may wish
to photocopy Line Master B-13 Summary Chart of Types of Chemical
reactions and cut it up to separate the various cells. Place the set of items
in an envelope. Have students reassemble the table without the aid of
their textbooks. Prepare as many sets as you need for classroom use. You
may wish to photocopy a set on manila tag, which is more durable than
standard photocopy paper.
Chapter 6 Answers
!"
Key Concept Review
1. The opposite of a decomposition chemical reaction is a synthesis
chemical reaction.
2. “Syn-” means together. It is a suitable prefix for describing a
synthesis chemical reaction because in this type of reaction, two
single elements (either two metals or two non-metals) combine (“get
together”) to form a compound.
3. The two types of displacement chemical reactions are single
displacement reactions and double displacement reactions.
4. The general formula for a hydrocarbon compound is CxHy.
5. Fossil fuels are hydrocarbons formed from the remains of once-living
organisms.
6. The six different types of chemical reactions are: synthesis,
decomposition, combustion, single displacement, double
displacement, and neutralization.
7. Water is always produced in combustion reactions and in
neutralization reactions.
8. (a) double displacement reaction
(b) neutralization reaction
Connect Your Understanding
9. Scientists need to study many examples of chemical reactions
because there are so many different elements on Earth and so many
different compounds. Each set of reactions is unique and can have
important and often surprising applications.
10. (a) potassium and iodine ĺ potassium iodide
(b) cesium and chlorine ĺ cesium chloride
11. Carbon dioxide gas (CO2) and water (H2O) are always produced by
the combustion of hydrocarbons and carbohydrates.
12. word equation: magnesium chloride ĺ magnesium + chlorine
skeleton equation: MgCl2(s) ĺ Mg(s) + Cl2(g)
balanced chemical equation: MgCl2(s) ĺ Mg(s) + Cl2(g)
13. When combustion reactions release carbon dioxide gas into the
atmosphere, they contribute to global warming. Atmospheric carbon
dioxide gas prevents thermal energy from escaping into space. As the
levels of carbon dioxide gas have increased over the past century, the
average temperature on Earth has also increased. This global
warming will have large environmental, social, and economic effects.
Unit B: Chemical Reactions
125
Chapter 6 Answers
B: Chemical Reactions
14. (a)
(b)
(c)
(d)
(e)
(f)
(g)
synthesis
decomposition
single displacement
double displacement
combustion
double displacement
decomposition
15. This is a double displacement reaction. The balanced chemical
equation is: FeCl2(aq) + K2S(aq) ĺ FeS(s) + 2KCl(aq).
16. You would be able to see the iron(II) sulphide, FeS, in the bottom of
the container. You know this because the equation indicates that FeS
is a solid.
17. (a) decomposition: CaCl2(g) ĺ Ca(s) + Cl2(g)
(b) decomposition: 2NaN3(s) ĺ 2Na(s) + 3N2(g)
(c) double displacement: Pb(NO3)2(aq) + Cu2SO4(aq) ĺ PbSO4(s) +
2CuNO3(aq)
(d) decomposition: 2Ni2O3(s) ĺ 4Ni(s) + 3O2(g)
(e) combustion: CH4(g) + 2O2(g) ĺ CO2(g) + 2H2O(g)
(f) double displacement: 3NaI(aq) + AlCl3(aq) ĺ 3NaCl(aq)
+AlI3(s)
18. (a) double displacement: Na2SO4 + CaCl2 ĺ 2NaCl + CaSO4
(b) synthesis: 3Mg + 2N2 ĺ Mg3N2
(c) double displacement: Sr(OH)2 + PbBr2 ĺ SrBr2 + Pb(OH)2
(d) synthesis: 4Na + O2 ĺ 2Na2O
(e) synthesis: N2 + 3H2 ĺ 2NH3
(f) decomposition: 2HCl ĺ H2 + Cl2
(g) single displacement: 2AlI3 + 3Br2 ĺ 2AlBr3 + 3I2
(h) neutralization: HCl + NaOH ĺ NaCl + H2O
19. This is a synthesis reaction: Ca + I2 ĺ CaI2.
20. This is a single displacement reaction: Zn(s) + CuSO4(aq) ĺ Cu(s) +
ZnSO4(aq).
21. Mg(s) + Br2(g) ĺ MgBr2(s)
22. This is a double displacement reaction.
Word equation: zinc bromide + silver nitrate ĺ silver bromide + zinc
nitrate
Skeleton equation: ZnBr2(aq) + AgNO3(aq) ĺ AgBr(s) +
Zn(NO3)2(aq)
Balanced equation: ZnBr2(aq) + 2AgNO3(aq) ĺ 2AgBr(s) +
Zn(NO3)2(aq)
23. Yes, she is correct. The reactants for a neutralization reaction are
always an acid and a base, both of which are compounds.