What it does
Chemical reactions come in a few common shapes. This page shows real reactions as particle pictures: each ball is one atom, labelled with its symbol. Press Play or drag the slider and the atoms of the reactants move into their places in the products. Nothing is created or destroyed; the atoms only change partners.
For each reaction you choose its type:
- Combination: A + B → AB, such as magnesium burning in oxygen.
- Decomposition: AB → A + B, such as limestone breaking down when heated. The page says whether heat, electricity or light supplies the energy.
- Displacement: A + BC → AC + B, such as iron pushing copper out of copper sulfate solution.
- Double displacement: AB + CD → AD + CB, such as barium chloride and sodium sulfate giving a white precipitate, or an acid and a base neutralising each other.
After each answer you get the rule, what you would see in the lab, and whether the reaction is also redox. With the Class 10 level the redox part uses the oxygen and hydrogen view (oxidation is gaining oxygen or losing hydrogen); with Class 11 it gives the oxidation-number changes and the electron-transfer view.
It fits the Class 10 science chapter on chemical reactions and equations (types of reactions, oxidation and reduction, corrosion and rancidity) and the Class 11 chapter on redox reactions. To balance an equation of your own, use the equation balancer; to see why some metals displace others, try the reactivity series lab.
How to use it
- A reaction appears with its reactants and a particle picture. Press Play or drag the slider to see the products form.
- Tap the type you think it is. The right answer turns green; a wrong pick turns red.
- Read the explanation, what you would see, and the redox box.
- Press Next reaction for another. Every one of the 20 comes up once before any repeats. Your score is shown at the top and is forgotten when you leave the page.
- Use the Reaction list to jump to any reaction, and the Class 10 / Class 11 switch to change the redox explanation.
A worked example
Pick Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s). Before the reaction the copper atom is joined to the sulfate group (one S and four O); afterwards the iron atom has taken its place and the copper stands alone. One element has swapped places with another inside a compound, so it is a displacement reaction.
It is also redox. In Class 10 terms, iron is more reactive than copper and takes its place in the compound. In Class 11 terms, iron goes from oxidation number 0 to +2 (it loses two electrons, so it is oxidised) and copper goes from +2 to 0 (it gains them, so it is reduced). In the lab you see a brown coat on an iron nail while the blue solution fades to pale green.
Now pick CaCO₃(s) → CaO(s) + CO₂(g): one substance gives two, so it is decomposition (by heat). No oxidation number changes, so it is not redox.
FAQ
Is oxidation a fifth type? Not in this sorting. Redox describes what happens to electrons and can happen alongside the other types: burning magnesium is both combination and redox.
Why does the hydrogen in CuO + H₂ count as displacement? Hydrogen takes copper’s place next to the oxygen. Many books show this reaction mainly as an example of redox: copper oxide is reduced and hydrogen is oxidised.
Are these experiments safe to try? Some are done in school labs under a teacher’s supervision. Others, like heating lead nitrate, give off poisonous gases. Do not try them at home.
Is this from the NCERT book? It covers the same topic with fibub’s own pictures and wording. fibub is not part of NCERT.
Where the numbers come from
- The reactions, their types, observations and oxidation-number changes are general chemistry facts as taught in school, written fresh for fibub.
- Every equation is checked to be balanced atom by atom by the page's own formula parser, and the parser is checked against hand counts (for example Pb(NO₃)₂ has 1 Pb, 2 N and 6 O).
Standard scientific values, such as constants, atomic weights and melting points, are facts found in every textbook; we name where ours were checked. If you are an author or publisher and want a value, a credit or a table changed or removed, tell us and we will act quickly.
Last updated 2026-11-09.