To balance a chemical equation, follow these key steps:

1. Write the unbalanced equation with correct formulas for all reactants and products.
2. Count the atoms of each element on both sides of the equation to see which elements are unbalanced.
3. Adjust coefficients (the numbers in front of molecules) to balance the atoms. Only coefficients can be changed; subscripts within chemical formulas must remain the same because changing them alters the substances involved.
4. Start balancing with elements that appear in only one reactant and one product to simplify the process. Then balance elements that appear in multiple compounds.
5. Repeat counting and adjusting coefficients until the number of atoms for each element is the same on both sides.
6. Ensure all coefficients are whole numbers. If you get fractions, multiply the entire equation by the denominator to clear them.

Example: Balancing H₂ + O₂ → H₂O

• Count atoms:
  • Left: 2 H, 2 O
  • Right: 2 H, 1 O
• Balance oxygen by placing a coefficient of 2 in front of H₂O:
  • H₂ + O₂ → 2 H₂O
  • Now right side has 4 H and 2 O.
• Balance hydrogen by placing a coefficient of 2 in front of H₂:
  • 2 H₂ + O₂ → 2 H₂O
  • Both sides now have 4 H and 2 O atoms.

The equation is balanced

. This method applies universally: count atoms, adjust coefficients, recount, and repeat until balanced. It respects the law of conservation of mass, ensuring atoms are neither created nor destroyed in the reaction