Materials Used

• 2 bottles 
• Salt and water mixture 
• Screw (14 pcs.)
• Wires
• 9V battery 
• Gluegun 
• Pipe and gas collection 

Theory 

Electrolysis is the process of converting water into its constituent molecules; hydrogen and oxygen using electricity. The electrolysis is performed in an electrolytic cell where two sets of electrodes are immersed in a conductive solution thereby working as a cathode and an anode. The need of conductive ions is to carry charge within the cell. At the anode, water is oxidized to oxygen gas and hydrogen ions. At cathode, water is reduced to hydrogen gas and hydroxide ions. 

In order to obtain overall reaction, the reduced half-reaction was multiplied by two to equalize the reactions. The hydrogen gas and oxygen gas can be reacted again to produce electricity and water. 

The reaction takes place higher voltages due to losses incurred and also overvoltage of the electrode. 

Factor affecting electrolysis

1. Number of available anions and cations in the solution.
2. Mobility rate of ions to reach the electrode.
3. Activation energy needed for electron transfer from the electrode to the electrolyte ions. 
4. The effect of gas bubble surrounding the electrode on the further electrotransfer. 

Experiment 

The experiment was conducted at home using locally available materials. Due to the absence of KOH, sodium chloride was used for the electrolyte solution. A set of 7 screws were used as cathode and another set of 7 screws were made to work as anode. A 9V battery was used to pass DC current to the electrodes and two teaspoon of salt was used for the electrolytic solution. A pipe was used to carry the gas from the electrolyte cell to a syringe for gas demonstration. 

Findings

It was seen that when current was passed through the electrodes, a reaction occurred in the cell forming bubbles on the surface of electrodes. It was also seen that a brown color layer was discharged on the surface of electrodes and in the solution due to the chlorine present in the salt. After 10 minutes of reaction, when a matchstick was brought near the syringe, a blue flame was seen which demonstrated the presence of hydrogen gas but unfortunately, the flame disappeared within seconds. The flame was not witnessed thereafter. The experiment was also conducted increasing the amount of salt in the solution which resulted in faster bubble formation. The experiment was also conducted using heated saltwater which increased the bubble formation a bit faster.

Challenges

1. It was difficult to find KOH solution in the nearby places. 
2. Making the setup leakproof was a challenge.
3. Formation of chlorine and leakage of the gas was a threat. 
4. The electrodes could not be used more than twice due to disposition of rust-like materials on the surface which could not be removed. 

Learnings

• The necessity of applying the theory in practical was seen.
• A good utilization of time to verify theoretical knowledge through practical exposure. 
• Chlorine should be avoided from the solution since it is harmful. 
• It was seen that the electrolysis was impacted by various factors.