Balance Chemical Equation Calculator

Background

Balancing chemical equations is a fundamental skill in chemistry that ensures the law of conservation of mass is followed. This calculator helps students quickly and accurately find the correct coefficients to balance any chemical reaction, including complex molecules and polyatomic ions.

How to use the calculator

Enter a chemical equation in the input field above. Example: Fe + O2 = Fe2O3. Click "Balance" to see the balanced equation.

Formula & Equation Used

The calculator sets up a system of linear equations for each element:

Σ (coefficients \times atoms of element in compound) = same on both sides of the equation

coefficients: unknown integers that multiply each chemical species in the equation
atoms of element in compound: number of atoms of each element in each compound

Example Problem & Step-by-Step Solution

Problem:

Balance the chemical equation: Fe + O2 = Fe2O3

Solution:

Assign coefficients: a Fe + b O₂ = c Fe₂O₃
Write balance equations for each element:

Fe: a = 2c (1)

O: 2b = 3c (2)

Choose the smallest whole number for c to solve the equations: Let c = 1, then from (1) a = 2 and from (2) 2b = 3 → b = 3/2
To eliminate fraction, multiply all coefficients by 2: a = 4, b = 3, c = 2
Write balanced equation: 4 Fe + 3 O₂ = 2 Fe₂O₃