Balancing Equations Practice
Name ______________________
Part A: Identify the following parts of each chemical formula by circling the subscripts
and drawing a square around the coefficients.
H2
2HCl
4O2
CH4
3CO3
2NaOH
Part B: List the symbols for the atoms in each formula and give the number of each.
C2H6
2MgO
4P4O10
C=
Mg =
P=
H=
O=
O=
NH3
3 Al(OH)3
2 H2O2
Part C: Balance each of the following equations following the procedure described in
class. Be sure to show your work.
P + O2  P4O10
Mg + O2  MgO
P=
P=
Mg =
Mg =
O=
O=
O=
O=
HgO Hg + O2
Al2O3  Al + O2
Hg =
Hg =
Al =
Al =
O=
O=
O=
O=
BaCl2 + H2SO4  BaSO4 + HCl
Ba =
Ba =
Cl =
Cl =
H=
H=
S=
S=
O=
O=
T. Trimpe 2006 http://sciencespot.net/
Part D: Practice Problems – Balance each equation using the process from Part C.
Cl2 + NaBr 
NaCl +
Br2
H2 + N2 NH3
Na + Br2  NaBr
CuCl2 + H2S  CuS + HCl
HgO + Cl2  HgCl + O2
C + H2  CH4
Challenge Problem: Give it your best shot!
C2H6 + O2 
CO2 + H2O
T. Trimpe 2006 http://sciencespot.net/
INFORMATION SHEET TO THE WORKSHEET.
PART A:
H2
HCl
O2
CH4
CO3
-Hydrogen as it naturally occurs.
-Hydrochloric acid, reacts mostly with metals to
-Oxygen as it naturally occurs.
-Methane gas; a natural hydrocarbon gas used as a combustible fuel.
-“Carbon trioxide can be made by blowing ozone at dry ice (solid CO2),
NaOH
and it has also been detected in reactions between carbon monoxide (CO)
and molecular oxygen (O2).”
-Sodium hydroxide a common ingredient in soaps and liquid plumber.
PART B:
C2H6
MgO
P4O10
NH3
Al(OH)3
H2O2
- Ethane; a natural hydrocarbon gas used as a combustible fuel.
- Magnesium oxide
- Tetraphosphorous decoxide
- Ammonia
- Aluminum hydroxide
- Hydrogen peroxide
PART C:
P + O2  P4O10
- Phospohorus & oxygen combining to form Tetraphosphorous
decoxide will react with water to make phosphoric acid. This is a
synthesis reaction.
Mg + O2  MgO - The bright white light in most fireworks and flares; Magnesium
oxide. This is a synthesis reaction.
HgO Hg + O2
- Mercuric oxide is a yellow pigment in paint. When heated the
compound decomposes into Mercury metal and oxygen gas.
Decomposition reaction.
Al2O3  Al + O2
- “By itself aluminum oxide does not decompose. By electrolysis it
gets split up into Al and O2.” Decomposition reaction.
BaCl2 + H2SO4  BaSO4 + HCl
- Barium chloride reacting with sulfuric acid to
produce Barium sulfate, which is “used as a … contrast medium in x-ray photography of the
digestive tract.” Hydro chloric acid is also formed as a product from this double-displacement
reaction.
M. W. Hall 2011
PART D:
Cl2 + NaBr 
NaCl +
Br2
- Chlorine reacting with Sodium bromide to produce
table salt and bromine liquid. Single-displacement
reaction.
H2 + N2 NH3
- Hydrogen reacts with nitrogen to produce ammonia.
This is a synthesis reaction.
Na + Br2  NaBr
- Sodium reacts with Bromine to produce sodium
bromide; the tablets that are placed in hot tubs and
pools. This is a synthesis reaction.
CuCl2 + H2S  CuS + HCl - Copper chloride reacts with Hydrogen sulfide to
produce copper sulfide and hydrochloric acid.
Decomposition reaction.
HgO + Cl2  HgCl + O2
- Mercuric oxide reacts with Chlorine to produce
Mercuric chloride and oxygen gas, this is a doubledisplacement reaction.
C + H2  CH4
- Carbon reacting with Hydrogen to produce the
hydrocarbon methane. This is a synthesis reaction.
CHALLENGE PROBLEM:
C2H6 + O2 
CO2 + H2O
- This is a combustion reaction of Ethane burning to
produce carbon dioxide and water.
M. W. Hall 2011