Here's why:
* Electrolysis involves using electricity to break down a compound into its constituent elements. In the case of water (H₂O), we want to split it into hydrogen gas (H₂) and oxygen gas (O₂).
* Water itself is a very poor conductor of electricity. It needs a substance that can dissolve and provide ions to carry the electrical current.
* Strong electrolytes, like salts, dissociate completely into ions when dissolved in water. These ions can then carry the electric current and facilitate the electrolysis process.
Here's how it works:
1. Dissolving the electrolyte: The salt is dissolved in water, creating a solution containing positively charged cations (e.g., Na⁺) and negatively charged anions (e.g., Cl⁻).
2. Applying current: When an electric current is passed through the solution, the positively charged cations migrate towards the negative electrode (cathode), and the negatively charged anions migrate towards the positive electrode (anode).
3. Electrochemical reactions: At the electrodes, chemical reactions occur:
* Cathode: Water molecules gain electrons and are reduced to hydrogen gas (2H₂O + 2e⁻ → H₂ + 2OH⁻).
* Anode: Water molecules lose electrons and are oxidized to oxygen gas (2H₂O → O₂ + 4H⁺ + 4e⁻).
Important Note: Using a strong electrolyte is crucial. Weak electrolytes, which only partially dissociate, wouldn't provide enough ions to conduct the electricity effectively for water electrolysis.
