Study electrolysis of water

Materials Required

Water in a 250 mL beaker, common salt, a battery of 3 D type 1.5 V cells, cell holder, double cotton-covered copper connecting wires, Spatula and a switch. 



 Real lab procedure 

  • Take two long DCC (double cotton-covered) copper wires and fold one end of each into a U-shape. 
  • Fill the beaker about half with water. Add half a teaspoonful of common salt using a spatula. 
  • Insert the U-shaped connecting wire in water. Connect its other end to the positive terminal of the battery.       
  • Connect the negative terminal of the battery to a plug key. 
  • Connect the second U-shaped connecting wire to the cell’s negative terminal through the key. 
  • Insert the key into the plug. Wait for a few minutes. 
  • Now remove the key from the plug.  
  • Note down the observations. 


Simulation Procedure 

  • Click on the bottle cap to open the bottle. 
  • Drag and drop the spatula towards the bottle to take half a teaspoon of common salt from it. 
  • Drag and drop the spatula containing common salt towards the beaker containing water to drop the salt into the water to make it more conducting. 
  • Drag and drop the copper wires towards the beaker to immerse them inside the beaker containing water. 
  • Click on the check box to refer to the circuit diagram.  
  • Connect the end of one copper wire to the battery’s positive terminal.  
  • Connect the end of the other copper wire to the key. 
  • Connect the battery to the key. 
  • Click the key towards the switch on the circuit. 
  • Click on the key to turn off the circuit.  



  • We observe that small bubbles are formed on both electrodes. 
  • Smaller bubbles are formed on the electrode connected to the battery's positive terminal.
  • A more significant number of bubbles are formed on the electrode connected to the battery’s negative terminal. 
  • Bubbles are formed on the electrodes as long as the key remains inserted in the plug. 



The passage of an electric current through water causes a chemical reaction. As a result, bubbles are formed on the electrodes. This is due to the chemical effect of electric current. The water molecule (H2O) has hydrogen and oxygen atoms. When an electric current is passed through water, oxygen bubbles are released at the positive electrode and hydrogen bubbles are released at the negative electrode. As a water molecule has two hydrogen atoms for every oxygen atom, a larger number of bubbles are formed at the electrode connected to the negative terminal of the battery.



  • Care should be taken to avoid the excessive flow of current through the circuit.  
  • For this a proper resistance that may be connected to the electric circuit. 
  • Keep the two electrodes completely immersed in water.