Supersaturation using Sodium Acetate (AKA: heating pad)

Warning: This is not an expariment you should try at home, but an example of Supersaturation implimented in real world turms.  In other words, watch and learn, but don't try this at home kids

The chemical that is being used in this video is called Sodium Acetate (NaCH₃COO) which is the sodium salt of acetic acid. It is an inexpensive chemical produced in industrial quantities for a wide range of uses.

Sodium Acetate is considered Irritant. 
For full information refer to the MSDS sheet.

Whats happening

Sodium Acetate has been added to water until the point of Supersaturation.  When they are heated to around 100 °C, and subsequently allowed to cool, the aqueous solution becomes supersaturated. This solution is capable of supercooling to room temperature without forming crystals.

When the solution comes in contact with impurities (Dust, finger, metal disc in a heating pad) which causes the solution to crystallize into solid sodium acetate trihydrate again. The bond-forming process of crystallization is exothermic, hence heat is emitted. The latent heat of fusion is about 264–289 kJ/kg.  Unlike some other types of heat packs that depend on irreversible chemical reactions, sodium acetate heat packs can be easily recharged by boiling until all crystals are dissolved. Therefore they can be recycled indefinitely.

Other Applications for Sodium Acetate

Sodium Acetate is also used in the textile industry to neutralize sulfuric acid.  It is also a pickling agent in chrome tanning, and it helps to retard vulcanization of chloroprene in synthetic rubber production.

Sodium acetate may be added to foods as a seasoning, and to alcoholic beverages to decrease the risk of a hangover.

Superconductivity

Superconductivity is a phenomenon occurring in certain materials generally at very low temperatures, characterized by exactly zero electrical resistance and the exclusion of the interior magnetic field (the Meissner effect). Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It cannot be understood simply as the idealization of "perfect conductivity" in classical physics.

The electrical resistivity of a metallic conductor decreases gradually as the temperature is lowered. However, in ordinary conductors such as copper and silver, impurities and other defects impose a lower limit. Even near absolute zero a real sample of copper shows a non-zero resistance. The resistance of a superconductor, despite these imperfections, drops abruptly to zero when the material is cooled below its "critical temperature". An electric current flowing in a loop of superconducting wire can persist indefinitely with no power source.

For more information on Superconductivity refer to Wikipedia.

How Does a Van de Graaff Generator Work?

A Van de Graaff generator is an electrostatic machine which uses a moving belt to accumulate very high electrostatically stable voltages on a hollow metal globe. The potential differences achieved in modern Van de Graaff generators can reach 5 megavolts. The Van de Graaff generator can be thought of as a constant-current source connected in parallel with a capacitor and a very large electrical resistance.

How Nuclear Power works

Colour changing Milk

It's an explosion of color! Some very unusual things happen when you mix a little milk, food coloring, and a drop of liquid soap. Use the experiment to amaze your friends and uncover the scientific secrets of soap.

Materials

• Milk (whole or 2%)
• Dinner plate
• Food coloring (red, yellow, green, blue)
• Dish-washing soap (Dawn brand works well)
• Cotton swabs

How does it work?

Milk is mostly water but it also contains vitamins, minerals, proteins, and tiny droplets of fat suspended in solution. Fats and proteins are sensitive to changes in the surrounding solution (the milk).

When you add soap, the weak chemical bonds that hold the proteins in solution are altered. It's a free for all! The molecules of protein and fat bend, roll, twist, and contort in all directions. The food color molecules are bumped and shoved everywhere, providing an easy way to observe all the invisible activity. At the same time, soap molecules combine to form a micelle, or cluster of soap molecules. These micelles distribute the fat in the milk.

This rapidly mixing fat and soap causes swirling and churning where a micelle meets a fat droplet. When there are micelles and fat droplets everywhere the motion stops, but not until after you've enjoyed the show!

For more details on this expariment Steves Pangler Science.