Balancing Chemical Equations
Enter the coefficients to balance each equation. Leave blank or enter 1 for a coefficient of 1.
Common Questions
How do you balance a chemical equation?
Adjust coefficients (numbers in front of formulas) so that each element has the same number of atoms on both sides. Start with elements that appear in only one reactant and one product. Save hydrogen and oxygen for last. Never change subscripts.
Why must chemical equations be balanced?
The law of conservation of mass requires that atoms are neither created nor destroyed in a chemical reaction. Every atom present in the reactants must appear in the products.
What is the difference between a coefficient and a subscript?
A coefficient is the number in front of a chemical formula and multiplies everything in the formula. A subscript is the small number within a formula (like the 2 in H2O) and is fixed by the compound's identity. Only coefficients can be changed when balancing.
What are common types of reactions to balance?
Combustion (fuel + O2 → CO2 + H2O), synthesis (A + B → AB), decomposition (AB → A + B), single replacement (A + BC → AC + B), and double replacement (AB + CD → AD + CB). Each type has characteristic balancing patterns.