By Chris Sherwood, seasoned chemist (Updated Aug 30, 2022)

Writing a balanced chemical equation is the cornerstone of every chemistry lesson. Whether you’re predicting a reaction or analyzing a lab result, a clear, accurate equation communicates the essential changes in matter.

Step 1 – Define the Reaction

Begin with a concise sentence that describes the transformation. Include every reactant and product, noting their physical states (s, l, g, aq). For example: Hydrogen gas reacts with oxygen gas to form liquid water.

Step 2 – List Reactants and Products

Place all reactants on the left side of the arrow and products on the right. Using the water example:

Hydrogen + Oxygen → Water

Step 3 – Convert to Chemical Symbols

Replace the names with their chemical formulas. The equation becomes:

H₂ + O₂ → H₂O

Step 4 – Balance the Equation

Adjust coefficients so that each element appears the same number of times on both sides and the total charge remains zero. For water, add a coefficient of 2 to hydrogen:

2 H₂ + O₂ → 2 H₂O

Now the equation is balanced and ready for use.

Follow these steps consistently to write accurate, reliable chemical equations in any scientific context.