Electrolysis of water

13/02/2013 18:35

Grade 9 students carry electrolysis of water at Shajara Science Laboratory

Experiment:          Electrolysis of water
Objective:   To explain changes takes place during electrolysis of water
D.C. power supply,  Electrolysis jar with two inert electrodes
      Connecting wires and alligator clips,  Distilled water
      Electrolyte: sulfuric acid solution H2SO4 or  potassium nitrate solution KNO3

Set up the apparatus 
Pour distilled water in the electrolysis jar /let water cover electrodes
Add few milliliters of sulfuric acid or potassium nitrate solutions into the jar
Turn on the D.C. power supply
Collect the gases formed at each electrode test tubes
Put a flame close to the mouth of each test tube then open it

Release of gas (bubbles) is observed at each electrode
The volume of gas formed at (-) pole is double that formed at (+) pole of power supply
The gas collected at the (-) pole burns with explosion /pop sound
The gas collected at the (+) pole lights a glowing splint
What does the release of gas indicate? 
What is the gas formed at each electrode?
What are the reactants and the products of this chemical reaction?
What is the type of this chemical reaction? Is this reaction spontaneous/non-spontaneous?
Write the balanced chemical equation of this reaction
What is the role of electrolyte added to distilled water?
Write the half reaction occurring at each electrode

Practice more:                   Worksheet

Electrolysis of water using ordinary apparatus


Electrolysis of water using Hoffman apparatus

The release of gas indicates that a chemical reaction is taking place at elecrodes

The electric energy is used to cause a chemical reaction

Hydrogen gas is released at cathode

Oxygen gas is released at anode

Volume of Hydrogen gas formed= 2 Volume of oxygen gas formed