Uses of chlorine

show chlorine reaction with water

Cl2(g) + H2O(l) → HClO(aq) + HCl(aq)

what is a disproportion reaction

when an element simultaneously oxidises and reduces

What happens when chlorine is used to purify swimming pools?

chloric(i) acid is an oxidising agent and kills bacteria by oxidation (bleach)

what happens when chlorine reacts with water in sunlight

2Cl2 (g) + 2H2O(l) → 4HCl (aq) + O2(g)

what can instead be added to swimming pools?

solid sodium chlorate (i)

show a reaction of chlorine with sodium hydroxide

Cl2(g) +NaOH(aq) → NaClO(aq) +NaCl(aq) +H2O(l)

oxidising power of halogens …. down the group

decreases

Test for halides

• make solution of halide

• acidify with dilute nitric acid, this prevents precipitation of other salts

• add few drops of silver nitrate solution

• Silver chloride- white, silver bromide-cream , silver iodide-yellow

• treat with dilute aqueous ammonia solution, silver chloride precipitate dissolves(colourless), silver bromide and iodide do not dissolve

• add concentrated ammonia , silver bromide dissolves, silver iodide remains as a precipitate