Sunday, December 8, 2013

Dancing naphthalene balls

In an earlier post, I talked about dancing sodium (here is the link). It involved high temperatures and could be called a little risky venture. In this post, we will see how we can make naphthalene balls dance in a glass.

Items needed: A glass or cylinder, oxalic acid, naphthalene balls, sodium bicarbonate (baking soda).

How to do it: In a glass of water(about 300 ml), mix about 30 grams of oxalic acid and stir to dissolve. Keep a little room in the glass. Put few naphthalene balls in the glass.

Now, prepare another solution of baking soda. Add a little of this solution to the glass which has the naphthalene balls.

Immediately you can see the solution bubbling and very soon the naphthalene balls will go up and down in a constant motion till the effervescence(bubbling) lasts.

What happens: Acid + soda produces carbon dioxide, whose bubbles get adhered to the surface of the naphthalene balls, and take them up when buoyant enough.

Extra tip: Same can be performed with soda water, but one has less control, which does take some of the fun away!

Caution: Oxalic acid is very toxic. Try not to handle with bare hands. Wash everything thoroughly when done.

Thursday, November 10, 2011

Dancing sodium

I want to begin with words of caution here, because this is a bit(?) dangerous. Sodium metal itself burns bare skin, gets burnt itself(although slowly) when in contact with air, kept under kerosene oil for this reason and handled with knives, tongs or suitable tools. And the amount of heat/fire that is generated here is not child's play. So be careful.

Cut a piece of the metal with knives or some tool under the kerosene sodium is kept. Cut a piece which is in noway bigger than 1cmx1cmx1cm. Next, find a metallic bucket(cannot be plastic or anything else that burns) and fill with water. Keep it in an open place, out of the house of course. Now take the piece of sodium with the tong and place it in the bucket of water. Distance yourself quickly(sometimes small explosions may follow) and enjoy the metal burning, hissing and dancing on water.

It happens because sodium, which is highly reactive, reacts with water to form sodium hydroxide - an alkali, and generates a lot of heat.

Tuesday, April 27, 2010

Solid state colour transformation

Take some potassium iodide and mercuric nitrate(or chloride) [all are white powders] and mix well. 1/5th of a teaspoon of each will be enough. Now, place the powder mixture on one side of a white paper. Fold the other side over the powder and rub the solid through the paper with your fingers.

The powder that has been rubbed well changes its colour from white to red, as mercuric iodide is formed.