Electrolysis of Water - Experiment, Equation

What is electrolysis of water?

The decomposition of water into hydrogen and oxygen gas as a result of an electric current passing through the water is called electrolysis of water. The standard potential of the reaction is −1.23 V which means it theoretically demands a potential difference of 1.23 volts to cleave water.

Electrolysis of water experiment

Electrolysis of Water Diagram

Electrolysis of Water Diagram

A considerable amount of energy is needed to get the atoms apart from each other. A battery can supply power. The water connects these terminals and acts as a bridge for energy flow. Read more about the types of batteries before moving to the next section of the experiment.

Baking soda is added in this experiment to make it as an electrolyte. An electrolyte is a kind of solution which can be split by electrolysis. Electro refers to electricity and energy and lysis denotes splitting.

Apparatus Required

  1. Distilled Water
  2. Two thumbtacks
  3. 9V Battery
  4. Small plastic container
  5. Tap water
  6. Stopwatch
  7. 2 test tubes
  8. Sodium bicarbonate
  9. Lemon
  10. Salt (table salt)
  11. Detergent (dish wash detergent)


Step 1: Put the thumbtacks at the bottom of the container such that the points can be pushed up in the container. Keep the space between them same as the terminals of the battery.

Step 2: Keep the container over the battery terminals with the thumbtacks.

Step 3: Fill the container with distilled water slowly.

Step 4: Put a pinch of Sodium bicarbonate.

Step 5: Hold the test tubes over every pin to collect the gas and note your observations.

Step 6: Remove the solution and repeat the above procedure with different sets that include:

  • Distilled water and salt.
  • Distilled water and detergent.
  • Distilled water and lemon juice.
  • Only distilled water.
  • Only tap water.

Electrolysis of water equation:

Reduction (cathode): 2 H+(aq) + 2e → H2(g)

Oxidation (anode): 2 H2O(l) → O2(g) + 4 H+(aq) + 4e

This half reaction can also be balanced with a base:

Cathode (reduction): 2 H2O(l) + 2e→ H2(g) + 2 OH(aq)

Anode (oxidation): 2 OH(aq) → 1/2 O2(g) + H2O(l) + 2 e

Therefore, the overall reaction becomes:

2 H2O(l) → 2 H2(g) + O2(g)


The baking soda solution provides the right amount of electricity, and the settlement with salt gives the best electrolysis.

When baking soda dissolves in water, it allows current between the terminals through the water. The baking soda solution produces hydrogen (H2), carbon dioxide (CO2) and oxygen (O2) gases.

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Frequently Asked Questions on Electrolysis of Water

explain what happens during the electrolysis of water ?

The electrons in the electric current result in a redox reaction. Since the sulfate ions do not electrolyse as easily as the water they are used to boost the conductivity of the water.

What is the process of electrolysis of water?

It is the decomposition of H2O into O2 and H2.

What is the efficiency of this experiment?

Approximately any new electrolysis plant is 80% efficient.

How can you test for electrolysis in the water?

Position a multimeter gauge at the low volt setting, the one which measures a scale from 0 to 1 volt. Connect the negative lead of the multimeter to the negative side of your battery should be connected to a ground source on the engine or the negative lead of the multimeter.

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