BALANCING OF CHEMICAL EQUATIONS
By: - Mr. Sabastian Martin
A chemical equation describes what happens in a chemical reaction. The equation identifies the
reactants (starting materials) and products (resulting substance), the formulas of the participants,
the phases of the participants (solid, liquid, gas), and the amount of each substance. Balancing a
chemical equation refers to establishing the mathematical relationship between the quantity of
reactants and products. The quantities are expressed as grams or moles.
It takes practice to be able to write balanced equations. There are essentially three steps to the
1. Write the unbalanced equation.
• Chemical formulas of reactants are listed on the left-hand side of the equation.
• Products are listed on the right-hand side of the equation.
• Reactants and products are separated by putting an arrow between them to show
the direction of the reaction. Reactions at equilibrium will have arrows facing both
2. Balance the equation.
• Apply the Law of Conservation of Mass to get the same number of atoms of every
element on each side of the equation. Tip: Start by balancing an element that
appears in only one reactant and product.
• Once one element is balanced, proceed to balance another, and another, until all
elements are balanced.
• Balance chemical formulas by placing coefficients in front of them. Do not add
subscripts, because this will change the formulas.
Law of Conservation of Mass:
Definition: A relation stating that in a chemical reaction, the mass of the products
equals the mass of the reactants.
Indicate the states of matter of the reactants and products.
• Use (g) for gaseous substances.
• Use (s) for solids.
• Use (l) for liquids.
• Use (aq) for species in solution in water.
• Write the state of matter immediately following the formula of the substance it
Worked Examples :
Tin oxide is heated with hydrogen gas to form ti