1. Section 7.3 Balancing Chemical Equations 1.To learn to write a balanced equation for a chemical reaction Objectives

2. Section 7.3 Balancing Chemical Equations A chemical reaction is balanced by using a systematic approach: –Write the formulas of the reactants and products to give the unbalanced chemical equation. –Balance by trial and error starting with the most complicated molecule(s). –At the end check to be sure the equation is balanced (same numbers of all types of atoms on the reactant and product sides).

3. Section 7.3 Balancing Chemical Equations Example: Hydrogen gas and oxygen gas combine to form liquid water. –Write the formulas of the reactants and products to give the unbalanced chemical equation. H 2 (g) + O 2 (g)  H 2 O(l)

4. Section 7.3 Balancing Chemical Equations Example: Hydrogen gas and oxygen gas combine to form liquid water. –Balance by trial and error starting with the most complicated molecule(s).

5. Section 7.3 Balancing Chemical Equations Example: Hydrogen gas and oxygen gas combine to form liquid water. –At the end check to be sure the equation is balanced (same numbers of all types of atoms on the reactant and product sides). 2H 2 (g) + O 2 (g)  2H 2 O(l)