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7. What must occur in order for an ion exchange reaction to take 3. Provide several examples of each of the four basic categories of
place? What is the result if this does not happen? chemical reactions, and describe how each illustrates a clear
8. Predict the products for the following reactions: (a) the combustion representation of the category.
of ethyl alcohol, C 2 H 5 OH, (b) the rusting of aluminum, and (c) the 4. Summarize for another person the steps needed to successfully
reaction between iron and sodium chloride. write a balanced chemical equation.
9. The formula for butane is C 4 H 10 . Is this an empirical formula
or a molecular formula? Explain the reason(s) for your
answer. INVITATION TO INQUIRY
10. How is the activity series for metals used to predict whether a
Rate of Chemical Reactions
replacement reaction will occur?
Temperature is one of the more important factors that influence the
11. What is a gram-formula weight? How is it calculated?
rate of a chemical reaction. You can use a “light stick” or “light tube” to
12. What are the meaning and the value of Avogadro’s number?
study how temperature can influence a chemical reaction. Light sticks
What is a mole?
and tubes are devices that glow in the dark and have become very pop-
ular on July 4 and other times when people are outside after sunset.
FOR FURTHER ANALYSIS They work from a chemical reaction that is similar to the chemical re-
action that produces light in a firefly. Design an experiment that uses
1. Analyze how you would know for sure that a pure substance you light sticks to find out the effect of temperature on the brightness of
have is a compound and not an element.
light and how long the device will provide light. Perhaps you will be
2. What are the advantages and disadvantages of writing a chemical able to show by experimental evidence that use at a particular tempera-
equation with chemical symbols and formulas rather than just ture produces the most light for the longest period of time.
words?

PARALLEL EXERCISES

The exercises in groups A and B cover the same concepts. Solutions to group A exercises are located in appendix E.
Group A Group B
1. Identify the following as empirical formulas or molecular 1. Identify the following as empirical formulas or molecular
formulas and indicate any uncertainty with (?): formulas and indicate any uncertainty with (?):
(a) MgCl 2 (a) CH 2 O
(b) C 2 H 2 (b) C 6 H 12 O 6
(c) NaCl
(c) BaF 2
(d) C 8 H 18 (d) CH 4
(e) CH 4 (e) F 6
(f) S 8 (f) CaF 2
2. What is the formula weight for each of the following compounds? 2. Calculate the formula weight for each of the following compounds:
(a) Copper(II) sulfate (a) Dinitrogen monoxide
(b) Carbon disulfide (b) Lead(II) sulfide
(c) Calcium sulfate (c) Magnesium sulfate
(d) Sodium carbonate (d) Mercury(II) chloride
3. What is the mass percentage composition of the elements in the 3. What is the mass percentage composition of the elements in the
following compounds? following compounds?
(a) Fool’s gold, FeS 2 (a) Potash, K 2 CO 3

(b) Boric acid, H 3 BO 3 (b) Gypsum, CaSO 4

(c) Baking soda, NaHCO 3 (c) Saltpeter, KNO 3
(d) Aspirin, C 9 H 8 O 4 (d) Caffeine, C 8 H 10 N 4 O 2
4. Write balanced chemical equations for each of the following 4. Write balanced chemical equations for each of the following
unbalanced reactions: unbalanced reactions:
(a) SO 2 + O 2 → SO 3 (a) NO + O 2 → NO 2
(b) P + O 2 → P 2 O 5 (b) KClO 3 → KCl + O 2
(c) Al + HCl → AlCl 3 + H 2 (c) NH 4 Cl + Ca(OH) 2 → CaCl 2 + NH 3 + H 2 O
(d) NaOH + H 2 SO 4 → Na 2 SO 4 + H 2 O (d) NaNO 3 + H 2 SO 4 → Na 2 SO 4 + HNO 3
(e) PbS + H 2 O 2 → PbSO 4 + H 2 O
(e) Fe 2 O 3 + CO → Fe + CO 2
(f) Mg(OH) 2 + H 3 PO 4 → Mg 3 (PO 4 ) 2 + H 2 O (f) Al 2 (SO 4 ) 3 + BaCl 2 → AlCl 3 + BaSO 4

272 CHAPTER 10 Chemical Reactions 10-22