Chemistry Experiments & Demonstrations
Chemistry is an experimental science. Sometimes the quickest way to understand a reaction is simply to see what happens.
This collection brings together short, clear animations of important chemistry experiments, practical techniques and laboratory tests.
Each demonstration focuses on the essential observations — colour changes, precipitates, gases, movement and other evidence of chemical change.
The animations are designed for students revising practical chemistry and for teachers looking for simple visual demonstrations to use in the classroom.
Alongside each experiment you’ll find a concise explanation of what to do, what to observe and the chemistry behind it.
Choose an experiment below and watch the chemistry happen.
Tests for Gases
Test for Hydrogen
Test for Oxygen
Test for Carbon Dioxide
Test for Ammonia
Test for Hydrogen Chloride
Test for Chlorine
Tests for cations in solution using aqueous sodium hydroxide - dropwise, then an excess
Magnesium ions in solution
Alminium ions in solution
Zinc ions in solution
Iron(II) ions in solution
Iron(III) ions in solution
Copper(II) ions in solution
Set 1 — Reactions with hydroxide ions
Magnesium
Mg²⁺(aq) + 2OH⁻(aq) → Mg(OH)₂(s)
No reaction with excess OH⁻.
Aluminium
Al³⁺(aq) + 3OH⁻(aq) → Al(OH)₃(s)
In excess hydroxide:
Al(OH)₃(s) + OH⁻(aq) → [Al(OH)₄]⁻(aq)
Zinc
Zn²⁺(aq) + 2OH⁻(aq) → Zn(OH)₂(s)
In excess hydroxide:
Zn(OH)₂(s) + 2OH⁻(aq) → [Zn(OH)₄]²⁻(aq)
Iron(II)
Fe²⁺(aq) + 2OH⁻(aq) → Fe(OH)₂(s)
No reaction with excess OH⁻.
Iron(III)
Fe³⁺(aq) + 3OH⁻(aq) → Fe(OH)₃(s)
No reaction with excess OH⁻.
Copper(II)
Cu²⁺(aq) + 2OH⁻(aq) → Cu(OH)₂(s)
No reaction with excess OH⁻.
______________ Test for Ammonium ions ___________________________
1. Formation of ammonia gas
NH₄⁺(aq) + OH⁻(aq) → NH₃(g) + H₂O(l)
2. Formation of the white smoke
NH₃(g) + HCl(g) → NH₄Cl(s)
The (s) in the second equation is important: the visible white smoke consists of tiny solid particles of ammonium chloride suspended in the air.
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Set 2 — Reactions with aqueous ammonia
Aqueous ammonia contains mainly dissolved ammonia molecules, NH₃(aq), but some ammonia reacts with water:
NH₃(aq) + H₂O(l) ⇌ NH₄⁺(aq) + OH⁻(aq)
The small concentration of OH⁻(aq) produced is responsible for forming the metal hydroxide precipitates.
Magnesium
Mg²⁺(aq) + 2OH⁻(aq) → Mg(OH)₂(s)
No further reaction with excess NH₃(aq).
Aluminium
Al³⁺(aq) + 3OH⁻(aq) → Al(OH)₃(s)
No further reaction with excess NH₃(aq).
Zinc(II)
Zn²⁺(aq) + 2OH⁻(aq) → Zn(OH)₂(s)
In excess ammonia:
Zn(OH)₂(s) + 4NH₃(aq) → [Zn(NH₃)₄]²⁺(aq) + 2OH⁻(aq)
Iron(II)
Fe²⁺(aq) + 2OH⁻(aq) → Fe(OH)₂(s)
No further reaction with excess NH₃(aq).
Iron(III)
Fe³⁺(aq) + 3OH⁻(aq) → Fe(OH)₃(s)
No further reaction with excess NH₃(aq).
Copper(II)
Cu²⁺(aq) + 2OH⁻(aq) → Cu(OH)₂(s)
In excess ammonia:
Cu(OH)₂(s) + 4NH₃(aq) → [Cu(NH₃)₄]²⁺(aq) + 2OH⁻(aq)
The key contrast is:
Zn²⁺ and Cu²⁺ precipitates dissolve in excess NH₃ because soluble ammine complexes form.
For copper(II), this gives the characteristic deep royal/dark blue solution.
Copper(II) with Ammonia Solution
Test for Ammonium Ions
Flame Tests for Metal Cations
