Balancing Equations
Balancing, Writing, and Naming
Equations
Balancing Equations
Balancing Equations

Law of Conservation
of Matter:
In a chemical reaction,
matter can be neither
created nor destroyed.
 In a chemical reaction,
the amount of
reactants equal the
amount of products.


Balancing Equations
Paraphrase:
 Law of Conservation of
Atoms:


The number of atoms of
each type of element
must be the same on
each side of the
equation.
Balancing Equations
 Hydrogen
 H2



+ oxygen
+ O2
water
H2O
Hydrogen and oxygen are diatomic
elements.
Their subscripts cannot be changed.
The subscripts on water cannot be
changed.
Balancing Equation
 H2

+ O2
H2O
Count the atoms on each side.
Reactant side:
 2 atoms H
 2 atoms O

Product side:
2 atoms H
1 atom O
Balancing Equations
 H2


+ O2
H2O
If the subscripts cannot be altered,
how can the atoms be made equal?
Adjust the number of molecules by
changing the coefficients.
Balancing Equations
 H2
+ O2
2H2O
Balancing Equations
 2H2




Reactant side:
4 atoms of H
2 atoms of O
It’s Balanced!
+ O2
2H2O
Product side:
4 atoms of H
2 atoms of O
Balancing Equations
 N2


+ H2
NH3
Nitrogen + hydrogen
ammonia
Count atoms.
Reactants:
 2 atoms N
 2 atoms H

Products:
 1 atom N
 3 atoms of H

Balancing Equations
Nothing is balanced.
 Balance the nitrogen first by placing a
coefficient of 2 in front of the NH3.

 N2
+ H2
2NH3
Balancing Equations
Hydrogen is not balanced.
 Place a 3 in front of H2.

 N2
+ 3H2
Reactant side:
 2 atoms N
 6 atoms H

2NH3
Product side:
2 atoms N
6 atoms H
Balancing Equations








Ca3(PO4)2 + H2SO4
Count atoms.
Reactants:
Ca – 3
P–2
O – 12
H–2
S–1
CaSO4 + H3PO4
product.
Ca – 1
P–1
O–8
H–3
S–1
Balancing Equations


Start by balancing the calcium atoms,
placing a coefficient of 3 in front of CaSO4.
Ca3(PO4)2 + H2SO4
3CaSO4 + H3PO4
Balancing Equations


The coefficient of 3 also multiplies the
sulfur atom by 3, so balance sulfur next.
Ca3(PO4)2 + 3H2SO4
3CaSO4 + H3PO4
Balancing Equations


A coefficient of 2 placed in front of
H3PO4 which balances both hydrogen
and phosphate.
Ca3(PO4)2 + 3H2SO4
3CaSO4 + 2H3PO4
Balancing Equations
Cu + H2SO4






CuSO4 + H2O + SO2
The sulfate group breaks up. Each atom
must be counted individually. Ugh!
Reactants:
 Products:
Cu – 1
 Cu – 1
H–2
 S – 2
S–1
 O - 6
O–4
 H – 2
Balancing Equations
Sulfur is not balanced.
 Place a two in front of sulfuric acid.
 Count atoms: 2 H2SO4 H – 4, S – 2,
O-8

Cu + 2H2SO4
CuSO4 + H2O + SO2
Balancing Equations
Hydrogen needs to be balanced so
place a 2 in front of the H2O.
 Count the number of atoms.

Cu + 2H2SO4
CuSO4 + 2H2O + SO2
Balancing Equations


Reactants: Cu – 1, H – 4, S – 2, O – 8
Products: Cu – 1, S – 1, O – 4, H – 4, O –
2, S – 1, O – 2 = Cu – 1, S – 2, H – 4, O
–8
 It’s balanced!
Cu + 2H2SO4
CuSO4 + 2H2O + SO2
Balancing Equations
 Balancing
 Balance
hints:
the metals first.
 Balance the ion groups next.
 Balance the other atoms.
 Save the non ion group oxygen and
hydrogen until the end.
Balancing Equations
This method of
balancing
equations is the
inspection
method.
 The method is
trial and error.
 Practice.

Writing and Naming
Nickel + hydrochloric acid
hydrogen

Nickel(II) chloride +
Write the corresponding formula
equation and then balance the
equation.
Writing and Naming



Write each formula independently.
Ignore the rest of the equation.
Balance the equation after writing the
formulas.
Ni + HCl
NiCl2 + H2
Ni + 2HCl
NiCl2 + H2


Writing and Naming

Remember the diatomic elements: H2, N2,
O2, F2, Cl2, Br2, and I2.
Writing and Naming
Cu + H2SO4
 CuSO4 + H2O + SO2

Balance the formula equation.
 Write the word equation.

Writing and Naming
Cu + 2H2SO4
 CuSO4 + 2H2O + SO2





Write the names:
Cu by itself is just copper. Copper(I) or
copper(II) would be incorrect.
H2SO4 should be named as an acid.
Sulfuric acid
Writing and Naming

CuSO4 has a SO42- group so Cu must
be 2+. Some metals must have
Roman Numerals. Copper(II)
sulfate
H2O is known as water.
 SO2 is a nonmetal compound. Its
name is either sulfur dioxide or
sulfur(IV) oxide.

Writing and Naming
Cu + 2H2SO4
 CuSO4 + 2H2O + SO2

Copper + sulfuric acid 
 Copper(II) sulfate + water + sulfur
dioxide

Balancing Equations
 Chapter
8
 Practice!
 Practice!
 Practice!