Stoichiometric coefficients express proportions that preserve elemental counts. This particle-count model applies the 2:1:2 molecular relationship for hydrogen, oxygen and water, using whole reaction packets. It illustrates limiting and excess reactants but not real molecular collision pathways, thermodynamic conditions or reaction speed. Ordinary chemical reactions reorganise electrons and bonds without transforming one element's nuclei into another.
Matter and chemistry · Discover & try
Can atoms disappear in a chemical reaction?
Reading level 5 of 5 · AdvancedChange
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reactant
A starting substance in a reaction.
product
A substance formed by a reaction.
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See how it works
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Virtual atom bookkeeping only; no gas mixing, ignition, reaction-rate or laboratory procedure is modelled.
What to look for
- Each element count is conserved
- Molecule counts can change
- An excess reactant can remain
Explain what you noticed
There are 3 H2 groups and 2 O2 groups. After one complete 2 H2+O2 packet reacts, what remains unused?
Keep this idea: Count each element before and after rearranging the groups.
Follow the sources
- American Chemical Society — What Is a Chemical Reaction?
- American Chemical Society — Controlling the Amount of Products
Source material checked 2026-10-28. Explanations and activities by Nepedia. Source links do not imply endorsement.
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