Heat Demonstrations

See also: Thermochemistry

Heat is a form of energy transfer that occurs when there is a difference in temperature between objects. This category focuses on how heat moves through conduction, convection, and radiation, and how it affects the state and behaviour of matter. Exploring heat helps explain natural processes and technological applications ranging from weather to energy systems.

Demonstration	Materials	Difficulty	Safety	Summary
Ball and Ring Expansion	★★★	★☆☆	★★☆	This demonstration shows the thermal expansion of metals. A metal ball can pass through a ring at room temperature, but when heated, it expands and no longer fits. Cooling the ball in water allows it to contract and pass through again.
Bimetallic Strip Thermostat	★★☆	★☆☆	★★☆	This demonstration uses a bonded copper–steel strip to show how temperature changes cause mechanical movement. Because the metals expand at different rates when heated, the strip bends, illustrating the principle of differential thermal expansion. This effect underpins many real-world devices, such as thermostats and circuit breakers, where heat is converted into mechanical motion for control purposes.
Black vs Silver Can Cooling	★★☆	★☆☆	★★☆	This demonstration shows how emissivity affects heat radiation by comparing the cooling rates of hot water in a black can versus a shiny silver can. The black can radiates heat more efficiently and cools faster than the silver can.
Black vs White Can Heating	★★☆	★☆☆	★☆☆	This experiment demonstrates how color affects heat absorption by comparing the water temperature in a black-painted can and a white-painted can after exposure to sunlight. The black can absorbs more energy, heating the water inside faster than the white can.
Burning Paper with Colliding Steel Balls	★★★	★☆☆	★☆☆	When two steel balls are struck together with paper between them, the collision generates enough heat to scorch and burn the paper.
Burning Steel Wool with a 9 Volt Battery	★☆☆	★☆☆	★★☆	In this experiment, fine-grade steel wool is ignited using a 9-volt battery. When the steel fibers complete the circuit, they heat up and react with oxygen in the air, producing glowing sparks and forming iron oxide. This demonstrates that metals, like iron, can burn under the right conditions.
Candle and Water Rising	★☆☆	★☆☆	★★☆	When a burning candle is covered with an inverted container standing in water, the candle eventually goes out and the water rises inside the container.
Comparing Evaporation Rates	★★☆	★★☆	★★☆	This demonstration shows how different liquids evaporate at different rates by measuring their temperature changes during evaporation. Students connect differences in evaporation rates to molecular structure and intermolecular forces using molecular models.
Heat Conduction of Different Materials	★★☆	★★☆	★★☆	This demonstration shows how heat conduction varies in different materials by using rods of copper, iron, and glass. Wax is used to attach small nails to the ends of the rods, and the heat from a Bunsen burner causes the nails to drop off in the order of conductivity.
Convection Among Friends	★☆☆	★☆☆	★☆☆	This interactive activity uses hand placement between partners to demonstrate convection, showing how heat transfers from warmer to cooler areas through moving air. It also introduces conduction when the partners’ hands touch directly.
Cutting Rope with Rope	★☆☆	★☆☆	★☆☆	This demonstration shows how one piece of rope can be used to cut through another by rapidly sawing back and forth. The heat and abrasion from friction weaken the fibers until the rope snaps. It’s a survival trick that illustrates the physics of friction and energy transfer.
Egg in a Bottle	★★☆	★☆☆	★★☆	A peeled hard-boiled egg is placed on the neck of a bottle. When lit matches are dropped into the bottle, the heated air expands and some escapes. As the air cools, it contracts, lowering the air pressure inside. The higher outside air pressure pushes the egg into the bottle.
Evaporative Cooling with Liquids	★☆☆	★☆☆	★☆☆	This activity demonstrates how evaporation causes cooling by comparing how water and rubbing alcohol feel when placed on the skin. As the liquids evaporate, they remove heat from the surface, showing how sweating helps regulate body temperature.
Fireproof Balloon	★☆☆	★☆☆	★★☆	A balloon filled with only air bursts quickly when exposed to a flame, but a balloon containing water can withstand the heat.
Flying Tea Bag	★☆☆	★☆☆	★★☆	An emptied tea bag is set on fire, and as it burns, hot air rises through convection. Once the bag becomes light enough, it is lifted into the air by the rising column of hot gases, demonstrating the principle behind hot air balloons.
Freeze a Beaker to a Board	★★☆	★★☆	★★☆	When ammonium nitrate and barium hydroxide are mixed, they undergo a strongly endothermic reaction that absorbs heat, lowering the temperature to around –25 °C to –30 °C. The beaker becomes so cold that water freezes, bonding the beaker to the wooden block beneath it.
Hot Air Balloon	★☆☆	★☆☆	★☆☆	This project demonstrates how hot air can make a lightweight plastic bag rise, using a hair dryer. The heated air fills the bag, making it less dense than the surrounding cooler air, which causes the bag to lift into the air.
Land vs Water Heating	★★☆	★☆☆	★☆☆	This experiment models how land and water surfaces heat and cool at different rates. By comparing temperature changes in soil (or sand) and water exposed to a heat lamp, students can better understand how the uneven heating of Earth’s surfaces affects weather and climate.
Light a Match With Superheated Steam	★★★	★★☆	★★★	Steam produced at atmospheric pressure is passed through heated copper tubing to become superheated, reaching several hundred degrees Celsius. The superheated steam demonstrates surprising effects when it comes into contact with paper and matches.
Metal Rod Conduction	★★☆	★☆☆	★★☆	A metal rod is heated at one end, and pieces of wax attached along its length melt one by one. This demonstrates how heat is conducted through the solid from the hot end toward the cooler end.
Nitinol Shape Memory Alloy	★★★	★☆☆	★★☆	Nitinol, a nickel-titanium alloy, demonstrates shape memory by returning to a pre-set shape when heated. Unlike ordinary wire, Nitinol “remembers” its original form and straightens itself when exposed to sufficient thermal energy.
Non-Burning Money	★☆☆	★★☆	★★☆	A dollar bill or paper soaked in a 50/50 alcohol-water solution is ignited. The alcohol burns brightly, but the bill remains unharmed because the water absorbs the heat and prevents the paper from reaching its ignition temperature.
Pizza Box Solar Oven	★☆☆	★☆☆	★☆☆	This activity demonstrates how sunlight can be harnessed to cook food. A pizza box lined with foil and sealed with plastic wrap becomes a solar oven, concentrating the sun’s rays and converting them into heat energy to warm or cook food.
Radiometer	★★☆	★★☆	★☆☆	This demonstration shows how light energy can be transformed into both thermal and mechanical energy using a radiometer. The black sides of the vanes absorb more light and heat up more than the white sides. Air molecules striking the heated black surfaces gain more energy and rebound with greater force than those striking the white sides, causing the vanes to spin. A partial vacuum inside the bulb reduces resistance, making the effect easier to see.
Rubens Tube	★★★	★★☆	★★☆	A Rubens tube is a long metal pipe with holes along its top, filled with propane and lit to produce flames. When sound waves are introduced through a speaker at one end, the flames reveal the standing wave pattern inside the tube, making sound waves visible as a dynamic flame display.
See Convection Currents	★☆☆	★☆☆	★★☆	A small container of hot, colored water is placed in a larger container of cold water. The warm water rises and circulates through the cold water, creating visible convection currents that illustrate heat transfer and density differences.
Simple Heat Conduction Experiment	★☆☆	★★☆	★★☆	This experiment compares how well different materials - metal, wood, and plastic - conduct heat by observing how quickly butter melts on each spoon after being heated in boiling water. The results demonstrate that metals conduct heat much more effectively than wood or plastic.
Soda Can Crusher	★☆☆	★★☆	★★☆	A small amount of water in an aluminum soda can is boiled to fill the can with steam. When the hot can is quickly inverted into cold water, the steam condenses, the internal pressure drops, and outside air pressure crushes the can.
Split Flame With Gauze	★★☆	★★☆	★★☆	A Bunsen burner flame is interrupted with a piece of wire gauze. The gas burns only above the gauze, not below it. This demonstrates how the gauze conducts heat away, preventing ignition below, while hot vapors reignite above the mesh.
Stirling Engine	★★★	★★☆	★☆☆	A low temperature Stirling engine placed over a cup of hot water runs as heat flows from the water to the engine, demonstrating energy conversion from heat to mechanical motion.

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