How to balance chemical equations

BALANCING EQUATIONS HELP

When balancing equations

• Write the correct chemical formula for each chemical species in the equation.
• Change the co-efficients (whole numbers on the left of a chemical formula) so that,

 the number and type of atoms on the reactants (left) = the number and type of atoms on the products (right)

When this is achieved the chemical equation is balanced.

Determine the number of atoms for each element in the following equations

1. Sodium + oxygen → sodium oxide

Unbalanced	Balanced
Na + O2 → Na2O  Element Reactants Products Balanced  Na atoms 1 How many? 2 How many?  O atoms 2 How many? 1 How many?   Look for an uneven number of O atoms. Double it.   ie. 2Na2O Na + O2 → 2Na2O  Element Reactants Products Balanced  Na atoms 1 How many? 4 How many?  O atoms 2 How many? 2 How many?   Finally, balance the number of Na atoms.	4Na + O2 → 2Na2O  Element Reactants Products Balanced  Na atoms 4 How many? 4 How many?  O atoms 2 How many? 2 How many?

  

2. Sodium + chlorine → sodium chloride

Unbalanced	Balanced
Na + Cl2 → NaCl  Element Reactants Products Balanced Na atoms 1 How many? 1 How many? Cl atoms 2 How many? 1 How many?	2Na + Cl2 → 2NaCl  Element Reactants Products Balanced Na atoms 2 How many? 2 How many? Cl atoms 2 How many? 2 How many?

 

3. Sodium + water → sodium hydroxide + hydrogen

Unbalanced	Balanced
Na + H2O → NaOH + H2  Element Reactants Products Balanced Na atoms 1 How many? 1 How many? H atoms 2 How many? 3 How many? O atoms 1 How many? 1 How many?	2Na + 2H2O → 2NaOH + H2  Element Reactants Products Balanced Na atoms 2 How many? 2 How many? H atoms 4 How many? 4 How many? O atoms 2 How many? 2 How many?

 

4. Sodium + hydrogen → sodium hydride

Unbalanced	Balanced
Na + H2 → NaH  Element Reactants Products Balanced Na atoms 1 How many? 1 How many? H atoms 2 How many? 1 How many?	2Na + H2 → 2NaH  Element Reactants Products Balanced Na atoms 2 How many? 2 How many? H atoms 2 How many? 2 How many?

 

5. Sodium + nitrogen → sodium nitride

Unbalanced	Balanced
Na + N2 → Na3N  Element Reactants Products Balanced Na atoms 1 How many? 3 How many? N atoms 2 How many? 1 How many?	6Na + N2 → 2Na3N  Element Reactants Products Balanced Na atoms 6 How many? 6 How many? N atoms 2 How many? 2 How many?