How to Solve & Balance Chemistry Equations

Chemical equations must be balanced on both the reactant and product side.

Chemical equations are considered balanced when the number of atoms of each type of element are the same on each side of the equation. For example, if you have four carbon atoms on the left, or reactant, side of the equation, you must also have four carbon atoms on the right, or product, side. The law of conservation of mass says that mass cannot be created nor destroyed in a chemical reaction. Balancing a chemical equation is simple once you understand the method.

Instructions

1. Determine how many of each type of atom is on each side of the equation. It is helpful to make a small chart separating the two sides. For example, in the chemical equation that follows, there are two hydrogen atoms, one sulfur atom, four oxygen atoms and one iron atom on the reactant side. On the product side there are two iron atoms, three sulfur atoms, 12 oxygen atoms and two hydrogen atoms.

   H2SO4 + Fe -> Fe2(SO4)3 + H2

2. Multiply a chemical on either side of the equation by a coefficient to make it equal the same number of atoms on both sides. It is useful to select an element that is only in one chemical on each side of the equation. In this example, multiply H2SO4 by three to have the same number of sulfur and oxygen atoms on both sides of the equation.

   3 H2SO4 + Fe -> Fe2(SO4)3 + H2

3. Continue balancing the other elements in the equation. Multiply Fe by two on the reactant side to balance it in the equation.

   3 H2SO4 + 2 Fe -> Fe2(SO4)3 + H2

4. Balance the final element, which in this case is hydrogen. Typically it is a good idea to save hydrogen and oxygen to balance at the end as they are sometimes in more than one chemical on each side of the equation.

   3 H2SO4 + 2 Fe -> Fe2(SO4)3 + 3 H2

References

• Fordham Preparatory School: Balancing Chemical Equations
• The Wright Stuff: How to Balance Chemical Equations