State the properties and uses of dichlorine.

(N/A) $(i)$ Physical properties: It is a greenish-yellow gas with a pungent and suffocating odour. It is about $2-5$ times heavier than air. It is soluble in water and can be liquefied easily into a yellow liquid which boils at $239 \ K$.
$(ii)$ Chemical properties:
Reaction with metals and non-metals: Chlorine reacts with all non-metals except nitrogen,oxygen,carbon,and inert gases. Chlorine forms chlorides with metals and non-metals.
$2 \ Al + 3 \ Cl_2 \rightarrow 2 \ AlCl_3$; $\quad P_4 + 6 \ Cl_2 \rightarrow 4 \ PCl_3$
$2 \ Na + Cl_2 \rightarrow 2 \ NaCl$; $\quad S_8 + 4 \ Cl_2 \rightarrow 4 \ S_2Cl_2$
$2 \ Fe + 3 \ Cl_2 \rightarrow 2 \ FeCl_3$
Affinity for hydrogen: Chlorine has a very strong affinity for hydrogen. It reacts with compounds containing hydrogen to form $HCl$.
$H_2 + Cl_2 \rightarrow 2 \ HCl$
$H_2S + Cl_2 \rightarrow S + 2 \ HCl$
$C_{10}H_{16} + 8 \ Cl_2 \rightarrow 16 \ HCl + 10 \ C$
Reaction with alkalies: With cold and dilute alkalies,chlorine produces a mixture of chloride and hypochlorite,but with hot and concentrated alkalies,it gives chloride and chlorate.
$2 \ NaOH + Cl_2 \rightarrow NaCl + NaOCl + H_2O$ (cold and dilute)
$6 \ NaOH + 3 \ Cl_2 \rightarrow 5 \ NaCl + NaClO_3 + 3 \ H_2O$ (hot and conc.)
Reaction with ammonia: With ammonia,the products obtained are ammonium chloride and dinitrogen.
$3 \ Cl_{2(g)} + 8 \ NH_{3(g)} \rightarrow N_{2(g)} + 6 \ NH_4Cl_{(s)}$ (excess ammonia)
With excess dichlorine,the product is $NCl_3$ (explosive).
$NH_{3(g)} + 3 \ Cl_{2(g)} \rightarrow NCl_3 + 3 \ HCl_{(g)}$
Bleaching and oxidizing action: Chlorine water loses its yellow colour on standing due to the formation of $HCl$ and $HOCl$. Hypochlorous acid $(HOCl)$ gives nascent oxygen $([O])$,which is responsible for the oxidizing and bleaching properties of chlorine.
$Cl_2 + H_2O \rightarrow HOCl + HCl$
$HOCl \rightarrow HCl + [O]$
$2 \ FeSO_4 + H_2SO_4 + Cl_2 \rightarrow Fe_2(SO_4)_3 + 2 \ HCl$
$Na_2SO_3 + Cl_2 + H_2O \rightarrow Na_2SO_4 + 2 \ HCl$
$SO_2 + 2 \ H_2O + Cl_2 \rightarrow H_2SO_4 + 2 \ HCl$
$I_2 + 6 \ H_2O + 5 \ Cl_2 \rightarrow 2 \ HIO_3 + 10 \ HCl$
The bleaching action of chlorine is permanent as it occurs through oxidation. It bleaches vegetable and organic matter in the presence of moisture.
$\text{Coloured matter} + [O] \rightarrow \text{colourless substance}$
$(iii)$ Uses: It is used for bleaching wood pulp,cotton,and textiles; for the extraction of gold and platinum; in the manufacture of dyes,drugs,and organic compounds like $CCl_4$,$CHCl_3$,$DDT$,and refrigerants; and for sterilizing drinking water.