Wednesday 25 April 2012

Lab Project


Energy and Science Projects
For Students

Splitting Water

H2O Hydrolysis

Electricity is "created" when certain chemicals react together. We use chemically-made electricity to power many machines from flashlights to a watch or sometimes a car. Yes, there are cars that run on electricity! The devices that store electricity are called batteries. Electricity can also be used to produce chemical changes.

Water is a simple chemical made from two gases: hydrogen and oxygen. Every molecule of water has two atoms of hydrogen for every atom of oxygen. H2O is the chemical formula for a molecule of water.

If an electrical current is passed through water between electrodes (the positive and minus poles of a battery), the water is split into its two parts: oxygen and hydrogen. This process is called electrolysis and is used in industry in many ways, such as making metals like aluminium. If one of the electrodes is a metal, it will become covered or plated with any metal in the solution. This is how objects are silverplated.

Try This!

You can use electricity to split water into its two gases (oxygen and hydrogen).

What You Need


  • A 9 volt battery
  • Two regular number 2 pencils (remove eraser and metal part on the ends)
  • Salt
  • Thin cardboard
  • Electrical wire
  • Small glass
  • Water





What to Do


  1. Sharpen each pencil at both ends.
  2. Cut the cardboard to fit over glass.
  3. Push the two pencils into the cardboard, about an inch apart.
  4. Dissolve about a teaspoon of salt into the warm water and let sit for a while.
  5. Using one piece of the electrical wire, connect one end on the positive side of the battery and the other to the black graphite (the "lead" of the pencil) at the top of the sharpened pencil. Do the same for the negative side connecting it to the second pencil top.
  6. Place the other two ends of the pencil into the salted water.



HYDROLYSIS

OPPOSITE ATTRACTS...

Hydrolysis is a chemical process in which a certain molecule is split into two parts by the addition of a molecule of water. One fragment of the parent molecule gains a hydrogen ion (H+) from the additional water molecule. The other group collects the remaining hydroxyl group (OH).

The most common hydrolysis occurs when a salt of a weak acid or weak base (or both) is dissolved in water. Water spontaneously ionizes into hydroxyl anions and hydrogen cations. The salt, too, dissociates into its constituent anions and cations. For example, sodium acetate dissociates in water into sodium and acetate ions. Sodium ions react very little with hydroxyl ions whereas acetate ions combine with hydrogen ions to produce neutral acetic acid, and the net result is a relative excess of hydroxyl ions, causing a basic solution.

However, under normal conditions, only a few reactions between water and organic compounds occur. In general, strong acids or bases must be added in order to achieve hydrolysis where water has no effect. The acid or base is considered a catalyst. They are meant to speed up the reaction, but are recovered at the end of it.

Now, try this.

1.      Put two pieces of wire in the bowl with distilled water.

2.      Connect one end to the positive pole of the transformer and the other to the negative pole.

3.      Dissolve some acid substance into the water.

4.      Turn on the transformer.

5.      Collect the gases into the test tubes.

Results


As the electricity from the battery passes through and between the electrodes, the water splits into hydrogen and oxygen.

Now answer:



1.      Which pole collects oxygen?

2.      Why do the oxygen bubbles go to the positive pole?

3.      Where is hydrogen collected?

4.      How much oxygen is there in the test tube?

5.      Do you know water formula?



Finally, draw the circuit between the electrodes, and write its description.


Technical English 1B - Unit 7 - Pages 52 up to 57 (1º & 2º Pol.)