# Holt Chemistry

## Educators

Problem 1

Describe the relationship between a synthesis reaction and a decomposition reaction.

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Problem 2

How does a coefficient in front of a formula
affect the number of each type of atom in
the formula?

Matthew L.

Problem 3

Define each of the following terms:
$$\begin{array}{l}{\text { a. decomposition reaction }} \\ {\text { b. double-displacement reaction }} \\ {\text { c. spectator ions }} \\ {\text { d. activity series }}\end{array}$$

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Problem 4

How does a coefficient differ from a
subscript?

Matthew L.

Problem 5

Give an example of a word equation, a
formula equation, and a chemical equation.

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Problem 6

A student writes the following statement in a
lab report: "During the reaction, the particles
of the reactants are lost. The reaction creates
energy and particles of the products"
$$\begin{array}{l}{\text { a. Explain the scientific inaccuracies in the }} \\ {\text { student's statement. }} \\ {\text { b. How could the student correct the }} \\ {\text { inaccurate statement? }}\end{array}$$

Matthew L.

Problem 7

Write an unbalanced chemical equation for
each of the following.
$$\begin{array}{l}{\text { a. Aluminum reacts with oxygen to produce }} \\ {\text { aluminum oxide. }} \\ {\text { b. Phosphoric acid, } \mathrm{H}_{3} \mathrm{PO}_{4} \text { , is produced }} \\ {\text { through the reaction between tetraphosphorus}} \\ {\text { decoxide and water. }}\end{array}$$

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Problem 8

Write the symbol used in a chemical equation to represent each of the following:
$$\begin{array}{l}{\text { a. an aqueous solution }} \\ {\text { b. heated }} \\ {\text { c. a reversible reaction }} \\ {\text { d. a solid }} \\ {\text { e. at a temperature of } 25^{\circ} \mathrm{C}}\end{array}$$

Matthew L.

Problem 9

Write an unbalanced formula equation for
each of the following. Include symbols for
physical states in the equation.
$$\begin{array}{c}{\text { a. solid zinc sulfide + oxygen gas } \longrightarrow} \\ {\text { solid zinc oxide + sulfur dioxide gas }} \\ {\text { b. aqueous hydrochloric acid + solid }} \\ {\text { magnesium hydroxide } \longrightarrow \text { aqueous }} \\ {\text { magnesium chloride + liquid water }}\end{array}$$

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Problem 10

Calcium oxide, $\mathrm{CaO}$ , is an ingredient in
cement mixes. When water is added, the
mixture warms up and calcium hydroxide,
$\mathrm{Ca}(\mathrm{OH})_{2}$ , forms.
$$\begin{array}{l}{\text { a. Is there any evidence of a chemical }} \\ {\text { reaction? }} \\ {\text { b. In the reaction above, how can you prove }} \\ {\text { that a chemical reaction has taken place? }}\end{array}$$

Matthew L.

Problem 11

Evaporating ocean water leaves a mixture
of salts. Is this a chemical change? Explain.

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Problem 12

Translate the following chemical equation
into a sentence:
$$\mathrm{CH}_{4}(g)+2 \mathrm{O}_{2}(g) \rightarrow \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(g)$$

Matthew L.

Problem 13

How does the process of balancing an equation illustrate the law of conservation of
mass?

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Problem 14

In balancing a chemical equation, why can
you change coefficients, but not subscripts?

Matthew L.

Problem 15

The white paste that lifeguards rub on their
nose to prevent sunburn contains zinc oxide,
$\mathrm{ZnO}(s),$ as an active ingredient. Zinc oxide
is produced by burning zinc sulfide.
$$2 \mathrm{ZnS}(s)+3 \mathrm{O}_{2}(g) \rightarrow 2 \mathrm{ZnO}(s)+2 \mathrm{SO}_{2}(g)$$
$$\begin{array}{l}{\text { a. What is the coefficient for sulfur dioxide? }} \\ {\text { b. What is the subscript for oxygen gas? }} \\ {\text { c. How many atoms of oxygen react? }} \\ {\text { d. How many atoms of oxygen react? }} \\ {\text { the total number of sulfur dioxide }} \\ {\text { molecules? }}\end{array}$$

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Problem 16

What are some of the characteristics of each
of these five common chemical reactions?
$$\begin{array}{l}{\text { a. combustion }} \\ {\text { b. synthesis }} \\ {\text { c. decomposition }} \\ {\text { d. displacement }} \\ {\text { e. double-displacement }}\end{array}$$

Matthew L.

Problem 17

What is an activity series?

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Problem 18

When would a displacement reaction cause
no reaction?

Matthew L.

Problem 19

What must form in order for a double-displacement reaction to occur?

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Problem 20

What are the products of the complete
combustion of a hydrocarbon?

Matthew L.

Problem 21

How do total and net ionic equations differ?

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Problem 22

Which ions in a total ionic equation are
called spectator ions? Why?

Matthew L.

Problem 23

Explain why a net ionic equation is the best
way to represent a double-displacement
reaction.

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Problem 24

The saline solution used to soak contact
lenses is primarily NaCl dissolved in water.
Which of the following ways to represent
the solution is not correct?
$$\begin{array}{l}{\text { a. } \operatorname{NaCl}(a q)} \\ {\text { b. } \mathrm{NaCl}(s)} \\ {\text { c. } \mathrm{Na}^{+}(a q)+\mathrm{Cl}^{-}(a q)}\end{array}$$

Matthew L.

Problem 25

How should each of the following substances be represented in a total ionic
equation?
$$\begin{array}{l}{\text { a. } \mathrm{KCl}(a q)} \\ {\text { b. } \mathrm{H}_{2} \mathrm{O}(l)} \\ {\text { c. } \mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}(a q)} \\ {\text { d. } \mathrm{AgCl}(s)}\end{array}$$

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Problem 26

Balance each of the following:
$$\begin{array}{l}{\text { a. } \mathrm{H}_{2}+\mathrm{Cl}_{2} \rightarrow \mathrm{HCl}} \\ {\text { b. } \mathrm{Al}+\mathrm{Fe}_{2} \mathrm{O}_{3} \rightarrow \mathrm{Al}_{2} \mathrm{O}_{3}+\mathrm{Fe}} \\ {\text { c. } \mathrm{Ba}\left(\mathrm{ClO}_{3}\right)_{2} \rightarrow \mathrm{BaCl}_{2}+\mathrm{O}_{2}} \\ {\text { d. } \mathrm{Cu}+\mathrm{HNO}_{3} \rightarrow \mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}+\mathrm{NO}+\mathrm{H}_{2} \mathrm{O}}\end{array}$$

Matthew L.

Problem 27

Write a balanced equation for each of the
following:
$$\begin{array}{c}{\text { a. iron(III) oxide + magnesium } \rightarrow} \\ {\text { magnesium oxide + iron }} \\ {\text { b. nitrogen dioxide + water } \rightarrow} \\ {\text { c. silicon tetrachloride + nitrogen monoxide }} \\ {\text { silicon dioxide + hydrochloric acid }}\end{array}$$

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Problem 28

Balance each of the following:
$$\begin{array}{l}{\text { a. Fe }+\mathrm{O}_{2} \rightarrow \mathrm{Fe}_{2} \mathrm{O}_{3}} \\ {\text { b. } \mathrm{H}_{2} \mathrm{O}_{2} \rightarrow \mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2}} \\ {\text { c. } \mathrm{C}_{8} \mathrm{H}_{18}+\mathrm{O}_{2} \rightarrow \mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O}} \\ {\text { d. } \mathrm{Al}+\mathrm{F}_{2} \rightarrow \mathrm{AlF}_{3}}\end{array}$$

Matthew L.

Problem 29

Write a balanced equation for each of the
following:
$$\begin{array}{r}{\text { a. propanol }\left(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{OH}\right)+\text { oxygen } \longrightarrow} \\ {\text { carbon dioxide }+\text { water }}\\{\text { b. aluminum }+\text { iron ( II) nitrate } \longrightarrow} \\ {\text { aluminum nitrate + iron }}\\{\text { c. lead(IV) oxide } \longrightarrow} {\text { lead(II) oxide + oxygen }}\end{array}$$

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Problem 30

Balance each of the following:
$$\begin{array}{l}{\text { a. } \mathrm{Zn}+\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2} \rightarrow \mathrm{Pb}+\mathrm{Zn}\left(\mathrm{NO}_{3}\right)_{2}} \\ {\text { b. } \mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}+\mathrm{NaOH} \rightarrow \mathrm{Na}_{2} \mathrm{C}_{2} \mathrm{O}_{4}+\mathrm{H}_{2} \mathrm{O}} \\ {\text { c. } \mathrm{Al}+\mathrm{CuSO}_{4} \rightarrow \mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}+\mathrm{Cu}}\end{array}$$

Matthew L.

Problem 31

Write a balanced equation for each of the
following:
$$\begin{array}{c}{\text { a. copper(II) sulfate }+\text { ammonium sulfide } \rightarrow} \\ {\text { copper(II) sulfide + ammonium sulfate }} \\ {\text { b. nitric acid + barium hydroxide } \rightarrow} \\ {\text { water + barium nitrate }}\end{array}$$
$$\begin{array}{c}{\text { c. barium chloride + phosphoric acid } \rightarrow} \\ {\text { barium phosphate + hydrochloric acid }}\end{array}$$

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Problem 32

Complete and balance the equation for each
of the following synthesis reactions.
$$\begin{array}{ll}{\text { a. } Z n+O_{2} \longrightarrow} & {\text { c. } C l_{2}+K \longrightarrow} \\ {\text { b. } F_{2}+M g \rightarrow} & {\text { d. } H_{2}+I_{2} \longrightarrow}\end{array}$$

Matthew L.

Problem 33

Complete and balance the equation for the
decomposition of each of the following.
$$\begin{array}{ll}{\text { a. } \mathrm{HgO} \rightarrow} & {\text { c. AgCl } \rightarrow} \\ {\text { b. } \mathrm{H}_{2} \mathrm{O} \longrightarrow} & {\text { d. } \mathrm{KOH} \longrightarrow}\end{array}$$

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Problem 34

Complete and balance the equation for the
complete combustion of each of the following.
$$\begin{array}{ll}{\text { a. } C_{3} \mathrm{H}_{6}} & {\text { c. } C \mathrm{H}_{3} \mathrm{OH}} \\ {\text { b. } C_{5} \mathrm{H}_{12}} & {\text { d. } C_{12} \mathrm{H}_{22} \mathrm{O}_{11}}\end{array}$$

Matthew L.

Problem 35

Each of the following reactions is a synthesis,
decomposition, or combustion reaction. For
each reaction, determine the type of reaction
and complete and balance the equation.
$$\begin{array}{l}{\text { a. } C_{3} \mathrm{H}_{8}+\mathrm{O}_{2} \rightarrow} \\ {\text { b. } \mathrm{Na}_{2} \mathrm{CO}_{3} \rightarrow} \\ {\text { c. } \mathrm{Ba}(\mathrm{OH})_{2} \rightarrow} \\ {\text { d. } \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}+\mathrm{O}_{2} \rightarrow}\end{array}$$

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Problem 36

Using the activity series in Appendix A, predict whether each of the possible reactions
listed below will occur. For the reactions that will occur, write the products and balance the equation.
$$\begin{array}{l}{\text { a. } \operatorname{Mg}(s)+\operatorname{CuCl}_{2}(a q) \rightarrow} \\ {\text { b. } \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(a q)+\mathrm{Zn}(s) \rightarrow} \\ {\text { c. } \mathrm{KI}(a q)+\mathrm{Cl}_{2}(g) \rightarrow} \\ {\text { d. } \mathrm{Cu}(s)+\mathrm{FeSO}_{4}(a q) \rightarrow}\end{array}$$

Matthew L.

Problem 37

Using the activity series in Appendix A, predict whether each of the possible reactions
listed below will occur. For the reactions that will occur, write the products and balance the equation.
$$\begin{array}{l}{\text { a. } \mathrm{H}_{2} \mathrm{O}(l)+\mathrm{Ba}(s) \rightarrow} \\ {\text { b. } \mathrm{Ca}(s)+\mathrm{O}_{2}(g) \rightarrow} \\ {\text { c. } \mathrm{O}_{2}(g)+\mathrm{Au}(s) \rightarrow}\end{array}$$

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Problem 38

Identify the type of reaction for each of the
following. Then, predict products for the
reaction and balance the equation. If no
reaction occurs, write "no reaction."
$$\begin{array}{l}{\text { a. } \mathrm{C}_{2} \mathrm{H}_{6}+\mathrm{O}_{2} \rightarrow} \\ {\text { b. } \mathrm{H}_{2} \mathrm{SO}_{4}+\mathrm{Al} \rightarrow} \\ {\text { c. } \mathrm{N}_{2}+\mathrm{Mg} \rightarrow} \\ {\text { d. } \mathrm{Na}_{2} \mathrm{CO}_{3} \rightarrow} \\ {\text { e. } \mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}+\mathrm{Na}_{2} \mathrm{SO}_{4} \longrightarrow}\end{array}$$

Matthew L.

Problem 39

Identify the type of reaction for each of the
following. Then, predict products for the
reaction, and balance the equation."
reaction occurs, write "no reaction."
$$\begin{array}{l}{\text { a. water }+\text { lithium } \longrightarrow} \\ {\text { b. silver nitrate + hydrochloric acid } \rightarrow} \\ {\text { c. hydrogen iodide } \rightarrow}\end{array}$$

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Problem 40

Identify the type of reaction for each of the
following. Then, predict products for the
reaction, and balance the equation."
reaction occurs, write "no reaction."
$$\text{a}. \mathrm{HCl}(a q)+\mathrm{NaOH}(a q) \rightarrow\mathrm{NaCl}(a q)+\mathrm{H}_{2} \mathrm{O}(l)$$
$$\text{b}. \mathrm{Mg}(s)+2 \mathrm{HCl}(a q) \rightarrow \mathrm{MgCl}_{2}(a q)+\mathrm{H}_{2}(g)$$
$$\text{c}. \mathrm{CdCl}_{2}(a q)+\mathrm{Na}_{2} \mathrm{CO}_{3}(a q) \rightarrow 2 \mathrm{NaCl}(a q)+\mathrm{CdCO}_{3}(s)$$

Matthew L.

Problem 41

Write a total ionic equation and a net ionic
equation for each of the following reactions.
$$\begin{array}{l}{\text { a. ethanol }\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)+\text { oxygen } \longrightarrow} \\ {\text { b. nitric acid }+\text { lithium hydroxide } \longrightarrow} \\ {\text { c. lead(II) nitrate + sodium carbonate } \rightarrow}\end{array}$$

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Problem 42

Identify the spectator ions in each reaction
in item $41 .$

Matthew L.

Problem 43

Predict the products and write a net ionic
equation for each of the following reactions.
If no reaction occurs, write "no reaction."
$$\begin{array}{l}{\text { a. } \mathrm{K}_{2} \mathrm{CO}_{3}(a q)+\mathrm{CaCl}_{2}(a q) \longrightarrow} \\ {\text { b. } \mathrm{Na}_{2} \mathrm{SO}_{4}(a q)+\mathrm{AgNO}_{3}(a q) \rightarrow} \\ {\text { c. } \mathrm{NH}_{4} \mathrm{Cl}(a q)+\mathrm{AgNO}_{3}(a q) \rightarrow} \\ {\text { d. } \mathrm{Pb}(s)+\mathrm{ZnCl}_{2}(a q) \rightarrow}\end{array}$$

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Problem 44

Identify the spectator ions in each reaction
in item $43 .$

Matthew L.

Problem 45

Balance the following equations.
$$\text{a}. \mathrm{CaH}_{2}(s)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow\mathrm{Ca}(\mathrm{OH})_{2}(a q)+\mathrm{H}_{2}(g)$$
$$\text{b}. \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CCH}(g)+\mathrm{Br}_{2}(l) \longrightarrow\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CBr}_{2} \mathrm{CHBr}_{2}(l)$$
$$\text{c} \cdot \mathrm{Pb}^{2+}(a q)+\mathrm{OH}^{-}(a q) \rightarrow \mathrm{Pb}(\mathrm{OH})_{2}(s)$$
$$\text{d} . \mathrm{NO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l) \rightarrow \mathrm{HNO}_{3}(a q)+\mathrm{NO}(g)$$

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Problem 46

Write and balance each of the following
equations, and then identify each equation
by type.
$$\begin{array}{c}{\text { a. hydrogen }+\text { iodine } \rightarrow \text { hydrogen iodide }} \\ {\text { b. lithium + water } \longrightarrow} \\ {\text { lithium hydroxide + hydrogen }} \\ {\text { c. mercury(II) oxide } \longrightarrow \text { mercury + oxygen }} \\ {\text { d. copper + chlorine } \rightarrow \text { copper(II) chloride }}\end{array}$$

Matthew L.

Problem 47

Write a balanced equation, including all of
the appropriate notations, for each of the
following reactions.
$$\begin{array}{l}{\text { a. Steam reacts with solid carbon to form }} \\ {\text { the gases carbon monoxide and hydrogen. }} \\ {\text { b. Heating ammonium nitrate in aqueous }} \\ {\text { solution forms dinitrogen monoxide gas }} \\ {\text { and liquid water. }} \\ {\text { c. Nitrogen dioxide gas forms from the }} \\ {\text { reaction of nitrogen monoxide gas and }} \\ {\text { oxygen gas. }}\end{array}$$

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Problem 48

Methanol, $\mathrm{CH}_{3} \mathrm{OH},$ is a clean-burning fuel.
$$\begin{array}{l}{\text { a. Write a balanced chemical equation for }} \\ {\text { the synthesis of methanol from carbon }} \\ {\text { monoxide and hydrogen gas. }} \\ {\text { b. Write a balanced chemical equation for }} \\ {\text { the complete combustion of methanol. }}\end{array}$$

Matthew L.

Problem 49

Use the activity series to predict whether
the following reactions are possible.
$$\text {a}.\mathrm{Ni}(s)+\mathrm{MgSO}_{4}(a q) \longrightarrow{\mathrm{NiSO}_{4}(a q)+\mathrm{Mg}(s)}$$
$$\begin{array}{r}{\text { b. } 3 \mathrm{Mg}(s)+\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}(a q) \longrightarrow} {3 \mathrm{MgSO}_{4}(a q)+2 \mathrm{Al}(s)}\end{array}$$
$$\text{c} \cdot \mathrm{Pb}(s)+2 \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow{\mathrm{Pb}(\mathrm{OH})_{2}(a q)+\mathrm{H}_{2}(g)}$$

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Problem 50

Write the balanced equation for each of the
following:
$$\begin{array}{l}{\text { a. the complete combustion of propane gas, }} \\ {\mathrm{C}_{3} \mathrm{H}_{8}} \\ {\text { b. the decomposition of magnesium carbonate }} \\ {\text { c. the synthesis of platinum(IV) fluoride }} \\ {\text { from platinum and fluorine gas }} \\ {\text { d. the reaction of zinc with lead(II) nitrate }}\end{array}$$

Matthew L.

Problem 51

Predict the products for each of the following reactions. Write a total ionic equation
and a net ionic equation for each reaction. If no reaction occurs, write "no reaction."
$$\begin{array}{l}{\text { a. } \mathrm{Li}_{2} \mathrm{CO}_{3}(a q)+\mathrm{BaBr}_{2}(a q) \longrightarrow} \\ {\text { b. } \mathrm{Na}_{2} \mathrm{SO}_{4}(a q)+\mathrm{Sr}\left(\mathrm{NO}_{3}\right)_{2}(a q) \rightarrow} \\ {\text { c. } \mathrm{Al}(s)+\mathrm{NiCl}_{2}(a q) \rightarrow} \\ {\text { d. } \mathrm{K}_{2} \mathrm{CO}_{3}(a q)+\mathrm{FeCl}_{3}(a q) \rightarrow}\end{array}$$

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Problem 52

Identify the spectator ions in each reaction
in item $51 .$

Matthew L.

Problem 53

The following equations are incorrect in
some way. Identify and correct each error,
and then balance each equation.
$$\begin{array}{l}{\text { a. } \mathrm{Li}+\mathrm{O}_{2} \rightarrow \mathrm{LiO}_{2}} \\ {\text { b. } \mathrm{MgCO}_{3} \rightarrow \mathrm{Mg}+\mathrm{C}+3 \mathrm{O}_{2}} \\ {\text { c. } \mathrm{NaI}+\mathrm{Cl}_{2} \rightarrow \mathrm{NaCl}+\mathrm{I}} \\ {\text { d. } \mathrm{AgNO}_{3}+\mathrm{CaCl}_{2} \rightarrow \mathrm{Ca}\left(\mathrm{NO}_{3}\right)+\mathrm{AgCl}_{2}} \\ {\text { e. } 3 \mathrm{Mg}+2 \mathrm{FeBr}_{3} \rightarrow \mathrm{Fe}_{2} \mathrm{Mg}_{3}+3 \mathrm{Br}_{2}}\end{array}$$

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Problem 54

Although cesium is not listed in the activity
series in this chapter, predict where cesium
would appear based on its position in the
periodic table.

Matthew L.

Problem 55

Create an activity series for the hypothetical elements $\mathrm{A}, \mathrm{J}, \mathrm{Q},$ and $\mathrm{Z}$ by using the reaction information provided below.
$$\begin{array}{c}{\mathrm{A}+\mathrm{ZX} \rightarrow \mathrm{AX}+\mathrm{Z}} \\ {\mathrm{J}+\mathrm{ZX} \rightarrow \text { no reaction }} \\ {\mathrm{Q}+\mathrm{AX} \rightarrow \mathrm{QX}+\mathrm{A}}\end{array}$$

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Problem 56

When wood burns, the ash weighs much less
than the original wood did. Explain why the
law of conservation of mass is not violated
in this situation.

Matthew L.

Problem 57

Write the total and net ionic equations for
the reaction in which the antacid Al(OH) $_{3}$
neutralizes the stomach acid HCl. Identify
the type of reaction.
$$\begin{array}{l}{\text { a. Identify the spectator ions in this reaction. }} \\ {\text { b. What would be the advantages of using }} \\ {\text { Al(OH) }_{3} \text { as an antacid rather than }} \\ {\text { NaHCO_ }_{3} \text { , which undergoes the following }} \\ {\text { reaction with stomach acid? }}\end{array}$$
$$\begin{array}{c}{\mathrm{NaHCO}_{3}(a q)+\mathrm{HCl}(a q) \rightarrow}{\mathrm{NaCl}(a q)+\mathrm{H}_{2} \mathrm{O}(l)+\mathrm{CO}_{2}(g)}\end{array}$$

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Problem 58

The images below represent the reactants of
a chemical reaction. Study the images, then
$$\begin{array}{l}{\text { a. Write a balanced chemical equation for }} \\ {\text { the reaction that shows the states of all }} \\ {\text { substances. }} \\ {\text { b. What type of reaction is this? }}\end{array}$$

Matthew L.

Problem 59

Using the materials listed below, describe
a procedure that would enable you to
organize the metals in order of reactivity.
The materials are pieces of aluminum,
chromium, and magnesium and solutions
of aluminum chloride, chromium (III)
chloride, and magnesium chloride.

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Problem 60

Design an experiment for judging the value
and efficacy of different antacids. Include
NaHCO $_{3}, \operatorname{Mg}(\mathrm{OH})_{2}, \mathrm{CaCO}_{3},$ and $\mathrm{Al}(\mathrm{OH})_{3}$
in your tests. Discover which one neutralizes
the most acid and what byproducts form.
your experiment is approved, obtain the
necessary chemicals from your teacher and

Matthew L.

Problem 61

For one day, record situations that suggest that a chemical change has occurred.
Identify the reactants and the products, and state whether there is proof of a chemical
reaction. Classify each of the chemical reactions according to the five common reaction
types discussed in the chapter.

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Problem 62

Research safety tips for dealing with fires.
Create a poster or brochure about fire
safety in which you explain both these tips
and their basis in science.

Matthew L.

Problem 63

Choose several biodegradable items on the
market, and research the decomposition
reactions that occur. Take into account any
special conditions that must occur for the
information to the class to help inform the
students about which products are best for
the environment.

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Problem 64

Use the following terms to create a concept
map: a synthesis reaction, a decomposition
reaction, coefficients, a chemical reaction,
and a chemical equation.

Matthew L.

Problem 65

Which halogen has the shortest single
bond with hydrogen?

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Problem 66

What is the difference in length between
an $\mathrm{H}-\mathrm{Br}$ bond and an $\mathrm{H}-\mathrm{I}$ bond?

Matthew L.

Problem 67

Describe the trend in bond length as you
move down the elements in Group 17 on
the periodic table.

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Problem 68

Based on this graph, what conclusion can
be drawn about the relative sizes of halo-
gen atoms? Could you draw the same
conclusion if an atom of an element
other than hydrogen was bonded to an
atom of each halogen?

Matthew L.

Problem 69

Graphing Calculator
Least Common Multiples When writing
chemical formulas or balancing a chemical
equation, being able to identify the least com-
mon multiple of a set of numbers can often
help. Your graphing calculator has a least
common multiple function that can compare
two numbers. On a TI-83 Plus or similar
graphing calculator, press MATH 8 . The
screen should read "lcm(." Next, enter one
number and then a comma followed by the
other number and a closing parenthesis. Press
ENTER, and the calculator will show the least
common multiple of the pair you entered.
Use this function as needed to find the
$$\begin{array}{l}{\text { a. Tin(IV) sulfate contains } \mathrm{Sn}^{4+} \text { and } \mathrm{SO}_{4}^{2-}} \\ {\text { ions. Use the least common multiple of } 2} \\ {\text { and } 4 \text { to determine the empirical formula }} \\ {\text { for this compound. }}\end{array}$$
$$\begin{array}{l}{\text { b. Aluminum ferrocyanide contains } \mathrm{Al}^{3+} \text { ions }} \\ {\text { and } \mathrm{Fe}(\mathrm{CN})_{6}^{4} \text { ions. Use the least common }} \\ {\text { multiple of } 3 \text { and } 4 \text { to determine the empiri- }} \\ {\text { cal formula for this compound. }}\end{array}$$
$$\text{c. Balance the following unbalanced equation}.$$$$\text{___}\mathrm{P}_{4} \mathrm{O}_{10}(s)+\text{___}\mathrm{H}_{2} \mathrm{O}(g) \rightarrow\text{___}\mathrm{H}_{3} \mathrm{PO}_{4}(a q)$$
$$\text{d. Balance the following unbalanced equation}.$$
$$\text{___}\mathrm{KMnO}_{4}(a q)+\text{___}\mathrm{MnCl}_{2}(a q)+2 \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow\text{___}\mathrm{MnO}_{2}(s)+4 \mathrm{HCl}(a q)+2 \mathrm{KCl}(a q)$$