In this demonstration, a peeled potato is cut into the form of a candle and an almond slice is used as the candle’s “wick.” The teacher lights the almond slice on fire and it burns. The students see the object, and make observations about it. Continue reading
Reproduce beautiful, multicolour art patterns using paper chromatography! Various colour pigments that make up black inks can be separated using radial chromatography. Continue reading
In this demo, the teacher creates a tower of sodium acetate trihydrate from a supersaturated solution. Your students’ curiosity will grow as you demonstrate the concepts of supersaturation and crystallization!
The sodium acetate solution is a supersaturated solution. The seed crystal is the start of a chain reaction, which causes all of the sodium acetate trihydrate molecules to crystallize. Crystallizing means that a liquid is becoming a solid, or “freezing.” The solution is supersaturated and supercooled—this means that it contains more dissolved sodium acetate than a saturated solution and has been cooled to below its freezing point without crystallization occurring.
Flour is an ingredient that is found in most kitchens and used regularly for baking and cooking. Consequently, it is considered safe, and people do not regard the potential hazards. In reality, flour and dust explosions are extremely dangerous, and reducing the risk of such an explosion is a major concern to the agriculture and food processing industries.
The purpose of this demonstration/activity is to illustrate the importance of being aware of potentially harmful situations and practices in the workplace. In particular, the dustiness of a material can affect the nature of chemical reaction, affecting a safe working environment.
How does it work?
Flour is combustible. When sitting as a stable pile the fuel (flour) is more connected to other flour particles than oxygen particles. As dust, each dust particle is surrounded by oxygen particles. This supports the combustion of the flour particle. As each particle moves through the flame, the combustion moves with the particles. Flour explosions tend to be connected to the movement of flour through air. The source of ignition is often discovered to be a static discharge.
The boiling point of a liquid depends on the external air pressure. When water is placed under vacuum, the boiling point decreases and the water boils. Boiling, however, is an endothermic process—as the water boils, the temperature decreases, and the water soon freezes!
In this demo, pressure changes cause a sample of acetone freezes while still boiling.
This demo models how convection occurs in the atmosphere and hydrosphere by showing what happens at the interface of a hot fluid and a cold fluid. This simulates what happens when cold and hot air masses meet, as well as why/how the ocean regulates climate. Continue reading
In this demonstration, students will see a model showing that antibodies bind to antigens as an immune response to foreign invaders. Continue reading
Most people don’t need matches, safety glasses and hydrogen gas to crack open an egg. But then again, Steve always finds the most unusual method to do the simplest things. Don’t try this at home. Continue reading