Why must equations be balanced?

The law of conservation of mass states that matter cannot be created or destroyed. Every atom that enters a reaction must appear in the products.

What strategies help balance equations?

Start with elements that appear in only one reactant and one product. Balance metals first, then nonmetals, then hydrogen, and oxygen last. For redox reactions, use the half-reaction method.

Can I change subscripts to balance?

No, never change subscripts. Subscripts define the compound's identity. Changing them would create a different substance. Only adjust coefficients (the numbers in front of formulas).

Balanceador de Equações Químicas

Verifique se uma equação química está balanceada inserindo coeficientes e contagens atômicas.

Verifique se uma equação química está balanceada inserindo coeficientes e contagens atômicas.

Total de átomos no lado dos reagentes

Total de átomos no lado dos produtos

Formula

Total atoms of each element must be equal on both sides

What is This Tool?

A balanced chemical equation has the same number of each type of atom on both the reactant and product sides, satisfying the law of conservation of mass. Balancing ensures that matter is neither created nor destroyed in a reaction.

Formula

For each element:
  Sum of atoms on reactant side = Sum of atoms on product side

Only coefficients (not subscripts) may be changed to balance.

Worked Examples

1. Combustion of hydrogen

Given: H2 + O2 -> H2O (unbalanced)

Reactant: 2 H, 2 O

Product: 2 H, 1 O -- not balanced

Balance: 2H2 + O2 -> 2H2O

Now: 4 H, 2 O on each side

Result: Balanced: 2H2 + O2 -> 2H2O

2. Synthesis of ammonia

Given: N2 + H2 -> NH3 (unbalanced)

Balance nitrogen: coefficient 2 for NH3

Balance hydrogen: coefficient 3 for H2

N2 + 3H2 -> 2NH3

Result: Balanced: N2 + 3H2 -> 2NH3

Frequently Asked Questions