Activity 1.7 Class 10 Science -

Table of Contents

Aim of the activity

To perform the electrolysis of water using carbon electrodes and identify the gases collected in the test tube at the electrodes.

Activity 1.7 Class 10 Science diagram

Material used in the activity

Plastic mug
Rubber Stoppers
Carbon electrodes
6 Volt battery
Water
Sulphuric acid
7.Two test tubes
Switch
Wires

Procedure

We will take a plastic mug and drill two holes at its bottom and fit rubber stoppers in the both holes. Now we insert carbon electrodes in these rubber stoppers.

After that we will connect the electrodes to a 6-volt battery and fill the mug with water so that both electrodes must immersed. Now we add a few drops of dilute sulphuric acid to the water

Now after this arrangement, we will take two test tubes filled with water and invert them over the two carbon electrodes and switch on the current and leave the apparatus undisturbed for some time.

Observation

We can see bubbles at the both the electrodes when current is passed through them. These bubbles indicate the presence of gases in the test tube at the electrodes.

These gases displace water downward in the test tube.

We can see the gas collected at the cathode (negative electrode) displaces more water compared to the gas collected at the anode (positive electrode).

The test tube at the cathode contains double volume of gas compared to the test tube at the anode.

After removing the both test tubes, we bring the burning candle near the test tubes and observe what happens-

The gas collected at the anode causes the flame to burn more brightly.
The gas collected at the cathode extinguishes the flame with a popping sound

The test tube at the cathode contains hydrogen and the test tube at the anode contains oxygen gas. Hydrogen gas has double volume

Explanation

The process of electrolysis decomposes water into hydrogen and oxygen

Following reaction takes place at electrodes

At cathode

Reduction reaction takes place at cathode

2H⁺+ 2e^– →H2 gas

Hydrogen gas is produced at cathode.

At anode

2H2O →O2 gas + 4H⁺ +4e^–

Oxygen gas is produced at anode.

Water contains two hydrogen atoms for each oxygen atom so the volume of hydrogen gas produced is double that of oxygen.

Conclusion

This activity shows the electrolysis (decomposition) of water into hydrogen and oxygen. Hydrogen gas is collected at the cathode and oxygen gas is collected at the anode.

Hydrogen gas has double volume that of oxygen.

Activity 1.7 Class 10 Science