Coke versus Diet Coke Density Demo

This demonstration reviews the concept of density. It examines why certain objects float or sink in water and highlights some interesting information about cola versus diet cola soft drinks.

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This demo is part of the STAO demo collection.  Click here to check out all of them.

Potato Candle Demo

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

Supersaturation Tower – Flinn Scientific Canada

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.

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Teacher Demo/Student Activity: Powder Disaster

Introduction

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.

 

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Freezing by Boiling Demo – Flinn Scientific

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.

Click here for the complete instructions, courtesy of Flinn Scientific