Electrolysis

Electrolysis

1. Electrolysis is the breaking down of a compound using electrical energy.

2. The electricity used comes form a d.c (direct current) source, such as a battery.

3. It requires a liquid to conduct the electricity, called the electrolyte.

4. The compound is found in the electrolyte. The compound is broken down into componant parts.

5. You can Electrolyse Hydrochloric Acid

   • The electrolyte is a dilute solution of Hydrochloric Acid.
     • Applying a direct current to the electrolyte causes the hydrochloric acid to decompose into its two component parts.
       • Hydrogen Gas
         • Testing for Hydrogen: Hydrogen makes a "squeaky pop" with a lighted splint (The sound comes from the Hydrogen burning with Oxygen in the air to form H2O.
       • Chlorine Gas
         • Testing for Chlorine: Chlorine bleaches damp litmus paper, turning it white. (It may turn red for a moment first through - that's because a solution of chlorine is acidic.)

6. Electrolysis of Salt produces Chlorine

   • Sea Water or brine (sodium chloride solution) can be decomposed by electrlysis.
     • This is a great way to make chlorine gas.
     • Chlorine gas is toxic - so this makes the manufacture of it a hazardous process.
     • There are 3 main uses of chlorine.
       • 1. It is used to treat water supplies - it kills bacteria and other micro-organisms making the water safe to drink.
       • 2. It is needed in the manufacture of bleach.
       • 3. It is used to make the polymer poly(chloroethene) - PVC

7. Electrolysis of water gives you Hydrogen and Oxygen

   • When water is decomposed it gives two components.
     • Hydrogen Gas
       • Testing for Hydrogen: Hydrogen makes a "squeaky pop" with a lighted splint (The sound comes from the Hydrogen burning with Oxygen in the air to form H2O.
     • Oxygen Gas
       • Testing for Oxygen: You check for Oxygen by checking if the gas relights a glowing splint.

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