ES - Production of halogens Flashcards
How can most halogens be extracted?
By electrolysis of halide solutions.
What happens when you electrolyse concentrated aqueous solutions containing halide ions?
The halogen element is released at the cathode.
What happens to halide ions at the anode?
The halide ions lose electrons to the electrode and are oxidised to atoms which combine to form molecules.
How can chlorine be extracted from brine industrially?
By electrolysis.
What is brine?
A solution of water with a high concentration of salts - mainly sodium chloride but also some bromine and iodine salts.
Where does brine occur?
Naturally in salt lakes or as seawater, or can be made by dissolving rock salt in water.
You can only extract chlorine from ___________ sodium chloride.
Concentrated.
Why can you only extract chlorine from concentrated sodium chloride?
As in dilute solutions, the chloride ions aren’t discharged - they hang on to their electrons. The hydroxide ions lose electrons instead and the products at the anode are oxygen and water, not chlorine.
What will happen when you bubble chlorine gas through brine?
The chlorine will displace the bromine/iodine.
How do you extract bromine from brine?
Bubble chlorine gas through brine as this will displace the bromine as it is more reactive.
The bromine produced is then collected, condensed into a liquid and purified.
How do you extract iodine from brine?
Bubble chlorine gas through brine as this will displace the iodine as it is more reactive.
The iodine produced is then collected, purified and condensed into a grey solid.
