Oxidation and Reduction Demonstrations
See also: Electrochemistry
Oxidation and reduction describe paired processes in which electrons are transferred between substances. This category develops the language of oxidation states, identifies oxidising and reducing agents, and uses half-equations to track electron flow. Redox ideas help explain changes in energy, formation and breakdown of compounds, and processes that occur in natural and technological systems. Building confidence with redox thinking supports accurate explanations and clear chemical accounting.
| Demonstration | Materials | Difficulty | Safety | Summary |
|---|---|---|---|---|
| Potato / Lemon Battery | ★★☆ | ★☆☆ | ★☆☆ | By inserting copper and zinc electrodes into a potato, you can create a simple battery. |
| Ammonium Dichromate Volcano | ★★★ | ★★☆ | ★★★ | A small mound of ammonium dichromate is ignited so it decomposes with sparks and a dramatic color change from bright orange crystals to dark green chromium(III) oxide, resembling a miniature volcano. |
| Blue Bottle Experiment | ★★☆ | ★★☆ | ★★☆ | In the Blue Bottle Experiment, a solution of glucose, potassium hydroxide, and methylene blue alternates between colorless and blue when shaken. |
| Burning Paper with Ice | ★★★ | ★★☆ | ★★★ | Tissue paper (or another combustible material) is ignited using a chip of ice. The ice melts, releasing water, which reacts with sodium peroxide to produce sodium hydroxide, oxygen, and heat. |
| Can Ripper | ★★☆ | ★★☆ | ★★☆ | The inside of an aluminum soda can is scored to break its protective plastic lining. When copper(II) chloride solution is added, a single replacement redox reaction occurs, dissolving the aluminum along the scored line. With only the outer paint layer holding the can together, the can can be ripped apart easily with a twist. |
| Cannon Fire Reaction | ★★☆ | ★★☆ | ★★★ | Hydrogen peroxide reacts with potassium permanganate to generate bursts of oxygen that make a burning ethanol mixture crack, pop, and roar like cannon fire; adding a metal salt can color the flame. |
| Chemical Traffic Light | ★★★ | ★★☆ | ★★☆ | The Chemical Traffic Light experiment demonstrates reversible redox reactions using glucose, sodium hydroxide, and indigo carmine. The solution transitions through a sequence of colors (blue → green → red → yellow) and can be reset by shaking, as oxygen from the air re-oxidizes the indicator. |
| Copper Extraction Using Carbon | ★★☆ | ★★☆ | ★★☆ | When a mixture of copper(II) oxide and carbon is heated, the carbon reduces the copper oxide to form copper metal and carbon dioxide gas. This reaction demonstrates how some metals are extracted from their ores. |
| Dichromate Breathalyzer | ★★☆ | ★★☆ | ★★☆ | An orange chromic acid (or Acidified Dichromate) reagent is added to two cylinders, one with water and one with ethanol. The water sample stays orange, while ethanol is oxidized to acetic acid and the chromium(VI) reagent is reduced to green chromium(III). |
| Electrolysis of Sodium Chloride (Brine) | ★★☆ | ★★☆ | ★★☆ | Aqueous sodium chloride is electrolyzed with inert electrodes to produce hydrogen gas at the cathode, chlorine gas at the anode, and sodium hydroxide remaining in solution. |
| Luminol Chemiluminescence | ★★★ | ★★☆ | ★★☆ | When luminol is mixed with hydrogen peroxide in the presence of sodium hydroxide and potassium ferricyanide, a blue glow is produced. This reaction demonstrates chemiluminescence, where chemical energy is converted directly into light energy without heat. |
| Making Nitrogen Dioxide | ★★☆ | ★★☆ | ★★★ | When copper metal is added to concentrated nitric acid, a vigorous reaction occurs that dissolves the copper, producing a blue-green solution of copper nitrate and releasing brown nitrogen dioxide gas. |
| Silver Nitrate Christmas Tree | ★★☆ | ★★☆ | ★★☆ | Branching silver crystals are grown on a copper “tree” by immersing the copper in a dilute silver nitrate solution. A single-displacement redox reaction plates metallic silver onto the copper while the solution turns blue from copper(II) ions. |
| Thermite | ★★☆ | ★★☆ | ★★★ | The thermite reaction produces molten iron by reducing iron(III) oxide with aluminum powder. Once ignited, the highly exothermic reaction releases intense heat and light, creating a dramatic classroom demonstration of redox chemistry. |
| Thermite Spheres | ★★★ | ★★☆ | ★★☆ | Two rusty iron spheres wrapped in aluminum foil are struck together to initiate a redox reaction. The reaction releases energy in the form of a popping noise and sparks, demonstrating the principles of thermite chemistry in a controlled and safe way. |
| Vanadium Oxidation States | ★★★ | ★★☆ | ★★☆ | This experiment demonstrates the multiple oxidation states of vanadium by producing vivid colors (yellow, green, blue, dark-green, and purple) in a single solution. Starting from vanadium pentoxide, vanadium compounds are reduced with zinc and then re-oxidized with potassium permanganate, creating a reversible rainbow of colors. |
| Flaming Gummy Bear | ★★★ | ★★★ | ★★★ | A gummy bear (or sugar sweet) is dropped into molten potassium chlorate, which decomposes to release oxygen. The sugar rapidly combusts, producing heat, light, gas, and a dramatic flame. |
Materials
★☆☆ Easy to get from supermarket or hardware store
★★☆ Available in most school laboratories or specialist stores
★★★ Requires materials not commonly found in school laboratories
Difficulty
★☆☆ Can be easily done by most teenagers
★★☆ Available in most school laboratories or specialist stores
★★★ Requires a more experienced teacher
Safety
★☆☆ Minimal safety procedures required
★★☆ Some safety precautions required to perform safely
★★★ Only to be attempted with adequate safety procedures and trained staff