Electrolysis is the breaking down of
a compound using electrical energy.
The electricity used comes form a d.c (direct current) source, such as a battery.
It requires a liquid to conduct the electricity, called the electrolyte.
The compound is found in the electrolyte. The
compound is broken down into componant parts.
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.)
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
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.