Fundamental Concept
Balancing chemical equations requires you to make sure that there are an equal number of elements on the reactant side (left side) and the product side (right side).
To make it simpler, let's try to balance the chemical equation for water:
H2 + O2 → H2O
Step 1. Identify the number of elements on the reactant side and the product side.
Reactant Side
Hydrogen - 2
Oxygen - 2
Product Side
Hydrogen - 2
Oxygen - 1
Step 2. Identify which elements do not have an equal number.
In this current example, there is less oxygen on the product side (1) than there is on the reactant side (2).
Step 3. Balance the equation.
This can be done by inserting a number before each product or reactant. In this current example, the equation can be balanced as follows:
2H2 + O2 → 2H2O
Step 4. Double check that the number of elements are now equal.
Reactant Side
Hydrogen - 4
Oxygen - 2
Product Side
Hydrogen - 4
Oxygen - 2
Applying the Concepts to the Exercise
- 2KNO3 + 1H2CO3 → 1K2CO3 + 2HNO3
- 4FeS + 7O2 → 2Fe2O3+ 4SO2
- 1PCl5 + 4H2O → 1H3PO4 + 2HCl
- 2AgI + 1N2S → 1Ag2S + 2NaI
- 1SnO2 + 4H2 → 1Sn + 2H2O