electrolysis of water experiment explanation | science project | science exhibition | diy | howtofunda | class 10

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Electrolysis of water is a fascinating experiment that demonstrates the process of breaking water molecules (H2O) into their constituent elements, hydrogen (H2) and oxygen (O2), using an electric current.

This experiment illustrates the principles of electrolysis and helps understand the concept of redox reactions.

Materials Needed:

Two pencils (graphite acts as electrodes)
Two alligator clips or wires
Small containers (cups or glass jars)
Water
Table salt (sodium chloride) or baking soda (sodium bicarbonate)
9V battery or a low-voltage DC power supply
Safety goggles and protective clothing (optional but recommended)


Procedure:

Set up the experiment in a safe area, preferably on a non-flammable surface.

Fill the two containers with water.

Add a small amount of table salt or baking soda to one of the containers. This is to increase the conductivity of the water. Stir until the salt or baking soda dissolves completely.

Insert the pencils into the containers, ensuring that the graphite tips are submerged in the water.

Connect one end of the alligator clips or wires to the exposed metal part of the pencils (not the erasers).

Connect the other ends of the alligator clips or wires to the terminals of the 9V battery or DC power supply.

Observe the setup carefully. Bubbles should start forming at the tips of the pencils submerged in the water.

After a few moments, you will notice that bubbles collect faster at each pencil's tip. One pencil will produce more bubbles than the other.

Explanation:

During the electrolysis of water, the electric current causes a chemical reaction. At the pencil's tip connected to the positive terminal of the battery (anode), oxygen gas (O2) is formed through the oxidation of hydroxide ions (OH-) present in the water:

4OH- (aq) → 2H2O (l) + O2 (g) + 4e-

At the pencil's tip connected to the negative terminal of the battery (cathode), hydrogen gas (H2) is produced through the reduction of water molecules:

2H2O (l) + 2e- → H2 (g) + 2OH- (aq)

As a result, oxygen gas collects at one pencil's tip, and hydrogen gas collects at the other pencil's tip.