Balancing chemical equations is a fundamental skill in chemistry. A balanced equation ensures that the law of conservation of mass is satisfied — the number of atoms of each element must be the same on both sides of the equation.
Step 1: Write the unbalanced equation. Identify all reactants and products with their correct chemical formulas. For example: Fe + O₂ → Fe₂O₃. Never change the subscripts in a chemical formula — only adjust the coefficients.
Step 2: Count atoms on each side. In our example, the left side has 1 Fe and 2 O, while the right side has 2 Fe and 3 O. Since neither matches, we need to add coefficients to balance.
Step 3: Balance one element at a time. Start with the element that appears in the fewest formulas. For Fe + O₂ → Fe₂O₃: first balance Fe by putting 4 in front of Fe on the left and 2 in front of Fe₂O₃ on the right (4 Fe = 2 × 2 Fe). Then balance O: 2 Fe₂O₃ has 6 O, so put 3 in front of O₂ (3 × 2 = 6). Final answer: 4Fe + 3O₂ → 2Fe₂O₃.
Pro tips: balance metals first, then non-metals, then hydrogen and oxygen last. For complex equations, the algebraic method assigns variables to each coefficient and solves a system of equations. Practice with increasingly complex reactions to build your balancing intuition.