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Chemical Equations Exam Study Guide - ANSWERS
Exam Monday 3/2 and Tuesday 3/3
Be able to define and give examples of: Combustion Reaction, Decomposition Reaction,
Double-Replacement Reaction, Single-Replacement Reaction, Combination (Synthesis)
Reaction, Positive Tests for Products (H2, CO2, O2, H2O, & NH3), Catalyst, Chemical
Equation, Activity Series, Product, Reactant, Subscript, Coefficient, and Yield Sign
**Review over safety rules/procedures in lab**
Similar Multiple Choice Questions will appear on the exam:
1. Symbols used in equations, together with the explanations of the symbols, are shown
below. Which set is correct?
a. (g), grams
c. (aq), dissolved in water
b. (l), liters
d. (s), solid product
2. In the chemical equation H2O2 (aq) ! H2O (l) + O2 (g), the O2 is a ____.
a. catalyst
c. product
b. solid
d. reactant
3. Whatarethecoefficientsthatwillbalancetheskeletonequationbelow?
Fe2O3+CO!Fe+CO2
a.2,1,2,1
c.2,4,3,4
b.1,3,2,3 d.1,2,1,2
4.If you rewrite the following word equation as a balanced chemical equation, what will
the coefficient and symbol for Chlorine be?
Iron + Chlorine ! Iron (III) Chloride
a. 4 Cl2
c. 3 Cl2
b. 3 Cl
d. 4 Cl
5. The type of reaction that takes place when one element reacts with a compound to
form a new compound and a different element is a ________.
a. comination reaction
c. single-replacement reaction
b. decomposition reaction d. double-replacement reaction
6. If a comination reaction takes place between rubidium and bromine, the chemical
formula for the product is ______.
a. RuBr
c. RbBr2
b. Rb2Br
d. RbBr
7. Which of the following is a balanced equation representing the decomposition of lead
(IV) oxide?
a. 2 PbO ! Pb + 2 O
c. Pb2O ! 2 Pb + O
b. PbO2 ! Pb + O2
d. 2 PbO ! 2 Pb + O2
8. In the activity series of metals, which metal(s) will displace hydrogen from an acid?
a. only metals below hydrogen
c. only metals above hydrogen
b. any metal
d. only metals Li to Na
Short Answer: Complete and balance the following reactions.
9. 2 Zn + O2 ! 2 ZnO
10. 2 Ag2O ! 4 Ag + O2
11. Ca + 2 HNO3 ! Ca(NO3)2 + H2
12. SrCl2 (aq) + 2 AgNO3 (aq) ! Sr(NO3)2 + 2 AgCl
*13. 2 C2H2 + 5 O2 ! 2 H2O + 4 CO2
*14. 2 C6H6 + 15 O2 ! 6 H2O + 12 CO2
*15. 2 C6H14 + 19 O2 ! 14 H2O + 12 CO2
Below are word reactions. Write the formulas (Use the periodic table for charges, then
criss-cross), then balance. Hints: Don’t forget “Seven Heave Rule.”
16. silver nitrate + sodium bromide ! sodium nitrate + silver bromide
AgNO3 + NaBr ! NaNO3 + AgBr
17. potassium iodide + lead (II) nitrate ! lead (II) iodide + potassium nitrate
2 KI + PB(NO3)2 ! PBI2 + 2 KNO3
18. magnesium chloride + ammonium nitrate ! magnesium nitrate + ammonium chloride
MgCl2 + 2 NH4NO3 ! Mg(NO3)2 + 2 NH4Cl
19. iron (III) oxide + carbon ! iron + carbon monoxide
Fe2O3 + 3 C ! 2 Fe + 3 CO
20. sodium + water ! sodium hydroxide + hydrogen
2 Na + 2 H2O ! 2 NaOH + H2
Below are combination word reactions. Write the reactants formulas; predict the
products produced, (Use the periodic table for charges, then criss-cross), then balance.
Hints: Don’t forget “Seven Heaven Rule.”
Example problem: Calcium reacts with nitrogen
Answer:
3 Ca + 1 N2 ! 1 Ca3N2
21. calcium reacts with oxygen
2 Ca + O2 ! 2 CaO
22. hydrogen reacts with nitrogen
3 H2 + 1 N2 ! 2 H3N
23. silver reacts with sulfur
2 Ag + S ! Ag2S
24. chromium reacts with oxygen
4 Cr + 3 O2 ! 2 Cr2O3
25. aluminum reacts with bromine
2 Al + 3 Br2 ! 2 AlBr3
26. sodium reacts with iodine
2 Na + I2 ! 2 NaI
27. hydrogen reacts with chlorine
H2 + Cl2 ! 2 HCl
28. zinc metal reacts with oxygen gas
2 Zn + O2 ! 2 ZnO