UNIT 4: CHEMICAL REACTIONS STUDY GUIDE
Multiple choice:
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C__1.
Chemical reactions _____.
a. simply change the form or state of the reactants.
b. create new atoms.
c. always produce new substances.
d. create more matter than what they started with.
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B__2.
Which of the following is the correct skeleton equation for the
combination of solid zinc with liquid bromine to produce solid zinc bromide?
a. Zn2(s) + Br(l)  ZnBr2(s)
b. Zn(s) + Br2(l)  ZnBr2(s)
c. Zn(s) + Br2(aq)  ZnBr2(s)
d. ZnBr2(s)  Zn(s) + Br2(l)
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A__3.
A substance that is needed to speed up a reaction but is not a product or
a reactant is known as a ____.
a. catalyst
b. coefficient
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d. steroid
D__4. In a combustion reaction, one of the reactants is always ____.
a. a liquid
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c. spectator ion
b. water
c. a metal
d. oxygen
B__5. Which of the following statements is true about the decomposition of a
simple binary compound?
a. The products cannot be predicted.
b. The reactant is a single substance.
c. The reactant must always be a molecular substance.
d. The product is a single substance.
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C__6.
The reaction 2P2O5  4P + 5O2 is an example of which type of
reaction?
a. double replacement
b. single replacement
c. decomposition
d. combustion
e. synthesis
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D__7.
The equation CH4 + 2O2  CO2 + 2H2O is an example of which type of
reaction?
a. double replacement
b. single replacement
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c. decomposition
d. combustion
e. synthesis
E__8. The equation: 2Na + Cl2  2NaCl is an example of which type of reaction?
a. double replacement
b. single replacement
c. decomposition
d. combustion
e. synthesis
9. List 5 observations that, when seen, usually indicate a chemical change has
occurred:
1. color change
2. production of bubbles
3. new odor is produced
4. spontaneous temperature change
5. formation of a precipitate
Complete the following equations by predicting what products will form. Make sure
you balance each equation when finished. (Honors chem must also predict any
equations that are no reactions).
SINGLE REPLACEMENT:
10. 2Al + 3CuCl2  3Cu + 2AlCl3
11. Hg + CaSO4  Ca + HgSO4 (NR)
12. Sn + Mg(ClO3)2  Mg + Sn(ClO3)2 (NR)
13. Zn + H2SO4  H2 + ZnSO4
14. 2K + 2HOH  H2 +
2KOH
DOUBLE REPLACEMENTS: (Honors chem should mark all precipitates with a downward arrow and
write net ionic equations for those reactions that happen).
15. Pb(NO3)2 + K2S  2KNO3 + PbS↓
Pb2+ + S2-  PbS↓
16. MgCl2 + 2AgNO3  Mg(NO3)2 + 2AgCl↓
2Cl1- + 2Ag1+  2AgCl↓
17. 3KOH + H3PO4  3HOH + K3PO4 (NR)
18. MgI2 + 2KClO3  Mg(ClO3)2 + 2KI (NR)
19. (NH4)2SO4 + Ca(OH)2  2NH4OH + CaSO4↓
SO42- + Ca2+  CaSO4↓
Write balanced chemical equations for the following chemical changes. Be sure to include all phase notation and
indicate the catalyst where appropriate.
20. Calcium metal is moderately reactive. If solid turnings of calcium metal are added to water,
the metal begins to bubble. Hydrogen gas is formed and the water begins to turn cloudy as
relatively insoluble calcium hydroxide also forms.
Ca(s) + 2H2O(l)  H2↑ + Ca(OH)2↓
21. Magnesium hydroxide solution has been used for many years as an antacid (“milk of
magnesia”) because it reacts with the solution of hydrochloric acid in the stomach, producing
aqueous magnesium chloride and water.
Mg(OH)2(aq) + 2HCl(aq)  MgCl2(aq) + 2H2O(l)