CHAPTER 5: Chemical reactions
Worksheet 5.2
Science Quest 10: pages 199–201
Balancing chemical
equations
Answers
1. Word equations and formula equations can be used to describe a chemical reaction.
Example
Word equation:
methane + oxygen  carbon dioxide + water
Formula equation:
CH4 + 2O2  CO2 + 2H2O
Check that the number of atoms of each element is the same for the reactants and products.
Use the tabulated information to construct formula equations from the supplied word equations.
Name
Formula
Calcium oxide
CaO
Sodium
carbonate
Calcium
nitrate
Na2CO3
Ca(NO3)2
Name
Hydrochloric
acid
Formula
HCl
Name
Formula
Ethane
C2H6
Nitric acid
HNO3
Acetylene
C2H2
Sodium
chloride
NaCl
Calcium
carbonate
CaCO3
Formula equation
Calcium oxide + nitric acid  calcium nitrate
+ water
CaO + 2HNO3  Ca(NO3)2 + H2O
Sodium carbonate + hydrochloric acid
 sodium chloride + carbon dioxide + water
Na2CO3 + 2HCl  2NaCl + CO2 + H2O
Ethane + oxygen gas  carbon dioxide
+ water
2C2H6 + 7O2  4CO2 + 6H2O
Acetylene + oxygen  carbon dioxide
+ water
2C2H2 + 5O2  4CO2 + 2H2O
Calcium carbonate  calcium oxide
+ carbon dioxide
CaCO3  CaO + CO2
2. Iron (III) nitrate Fe(NO3)3 solution reacts with sodium hydroxide NaOH solution to form a
brown precipitate of iron (III) hydroxide Fe(OH)3. Sodium nitrate NaNO3 remains in solution as
it is a soluble compound.
Write the word equation and the balanced formula equation for this reaction.
Iron
(III) nitrate + sodium hydroxide  iron (III) hydroxide + sodium nitrate
.........................................................................................................................................................
Fe(NO
3)3 + 3NaOH  Fe(OH)3 + 3NaNO3
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Science Quest 10 Student Workbook