Reaction Rate Demonstrations

Reaction rate describes how quickly a chemical change takes place. This category looks at the factors that influence the speed of reactions, such as temperature, concentration, and surface area. Studying reaction rates helps explain why some processes happen instantly while others take much longer.

Demonstration	Materials	Difficulty	Safety	Summary
Elephant's Toothpaste	★★☆	★★☆	★★☆	30% hydrogen peroxide is added to a potassium iodide catalyst, detergent and food colouring, and oxygen bubbles rapidly produce a foam.
Alka-Seltzer Rocket	★★☆	★☆☆	★☆☆	A plastic film canister filled with water and alka-seltzer creates carbon dioxide gas, building pressure until the lid pops off and launches the canister like a rocket.
Glow Sticks at Different Temperatures	★☆☆	★☆☆	★★☆	Glow sticks glow due to chemiluminescence, a chemical reaction that releases light. Cold slows the reaction, producing a dimmer glow, while heat speeds it up, making the glow brighter but shorter-lived.
Disappearing X Reaction	★★☆	★★☆	★★☆	Hydrochloric acid reacts with sodium thiosulfate to produce sulfur, sulfur dioxide, and sodium chloride. As sulfur forms, the solution becomes cloudy. The time taken for a marked “X” beneath the beaker to disappear is used to measure reaction rate at different concentrations of sodium thiosulfate, allowing the order of the reaction to be determined.
Lycopodium Powder Fireball	★★☆	★★☆	★★★	Lycopodium powder, when ignited in a pile, burns slowly due to limited oxygen contact. When dispersed as a fine dust cloud and ignited, the vastly increased surface area causes rapid combustion, producing a dramatic fireball or small explosion.
Alka Seltzer Surface Area	★☆☆	★☆☆	★☆☆	Students investigate how the surface area of a solid affects the rate of a chemical reaction by comparing how long it takes whole, broken, and powdered Alka-Seltzer tablets to dissolve in water.
Potato Catalase Hydrogen Peroxide Decomposition	★★☆	★☆☆	★☆☆	Students observe how the enzyme catalase in potato accelerates the decomposition of hydrogen peroxide into water and oxygen. By comparing room-temperature, boiled, and frozen potato, they explore how temperature affects enzyme activity.
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.
Iodine Clock	★★☆	★★☆	★★☆	Two clear solutions are mixed, and after a short delay the mixture suddenly turns deep blue. The timing of the color change depends on concentration and temperature, making this a classic demonstration of chemical kinetics.
Chemical Sunset	★★☆	★★☆	★★☆	When sodium thiosulfate reacts with hydrochloric acid, colloidal sulfur particles form. As the particles grow, they scatter shorter wavelengths of visible light and transmit longer wavelengths, producing a sunset-like sequence of colors when projected with an overhead projector.

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