Because of the principle of the conservation of matter,

1
Chemical Equations

• Because of the principle of the conservation of
  matter,
• an equation must be balanced.
• It must have the same number of atoms of the
  same kind on both sides.

2
Scientists know that there must be the same
number of atoms on each side of the arrow.
3
To balance the chemical equation, you must add
COEFFICIENTS to the different parts of the
equation.
4
Step 1

• Determine the number of atoms for each element.

5
Determine the number of atoms for each element.

• Mg O2
  MgO

6
Determine the number of atoms for each element.

• Mg O2
  MgO
• 1 Magnesium 1 Magnesium
• 2 Oxygen 1 Oxygen

7
Try to add coefficients to the equation to get
the same number of atoms on each side.

• Mg O2
  MgO
• 1 Magnesium 1 Magnesium
• 2 Oxygen 1 Oxygen

8
Recount the atoms after adding a coefficient.

• Mg O2
  MgO
• 1 Magnesium 2 Magnesium
• 2 Oxygen 2 Oxygen
• Still out of balance

9
Add a coefficient to the other side

• Mg O2
  MgO
• 1 Magnesium 2 Magnesium
• 2 Oxygen 2 Oxygen
• Recount again

2
10
Recount the atoms

• Mg O2
  MgO
• 2 Magnesium 2 Magnesium
• 2 Oxygen 2 Oxygen
• Its balanced!!!

2
11
Types of reactions

• Synthesis
• Decomposition
• Single replacement
• Double replacement
• Combustion

12
Try this one

• H2O2 H2O
  O2

13
Problems

• Remember, count the atoms first
• Add coefficients to balance one of the atoms
  first
• Recount atoms
• Keep working the coefficients until atoms are
  balanced

14
Problems

• Na MgF2 NaF Mg

15
Problems

• Mg HCl MgCl2 H2

16
Problems

• H2 O2 H2O

17
Problems

• MgCO3 NaF Na2CO3 MgF2

18
Solutions

1. 2 Na MgF2 2 NaF Mg
2. 2 Mg 4 HCl 2 MgCl2 2 H2
3. 2H2 O2 2H2O
4. MgCO3 2NaF Na2CO3 MgF2

19
Challenge

• CO2 H2O C6H12O6 O2

20
Challenge solution

• 6 CO2 6 H2O C6H12O6 6 O2