Reactants, products and leftovers

Follow each complete group

2 H₂ + O₂ → 2 H₂O

H₂

O₂

The equation coefficients stay fixed. These controls change the available molecules.

Complete groups: 0

Every group uses exactly the ratio in the equation. If either reactant cannot supply a whole group, the remaining molecules stay unchanged.

Still needed: 2 H₂

Still needed: 1 O₂

Model notes

Each reactant has 0–8 molecules. Complete groups are counted with integer division; unused reactants remain as leftovers.
Grouped rows explain the stoichiometric counting. They do not represent molecules colliding in synchronized groups or the physical mechanism of a reaction.
The model assumes a reaction goes to completion as far as the supplied amounts allow. It does not simulate activation energy, rates, equilibrium, temperature or experimental conditions.
The molecule drawings show composition and illustrative bonds, not measured sizes or exact three-dimensional shapes.

Chemistry

Reactants, products and leftovers

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