Write a note on the preparation of sulphur dioxide. Explain the properties of sulphur dioxide. State its uses.

(N/A) Preparation:
$1$. Sulphur dioxide is formed together with a little $(6-8 \%)$ sulphur trioxide when sulphur is burnt in air or oxygen: $S_{(s)} + O_{2(g)} \rightarrow SO_{2(g)}$
$2$. In the laboratory,it is readily generated by treating a sulphite with dilute sulphuric acid: $SO_{3(aq)}^{2-} + 2H_{(aq)}^{+} \rightarrow H_{2}O_{(l)} + SO_{2(g)}$
$3$. Industrially,$SO_{2}$ is obtained as a by-product of the roasting of sulphide ores: $4FeS_{2(s)} + 11O_{2(g)} \rightarrow 2Fe_{2}O_{3(s)} + 8SO_{2(g)}$
Properties:
$(i)$ Physical properties: Sulphur dioxide is a colourless gas with a pungent smell and is highly soluble in water. It boils at $263 \ K$ and liquefies at room temperature under a pressure of $2 \ atm$. The shape of $SO_{2}$ is angular. It is a resonance hybrid of two canonical forms.
$(ii)$ Chemical properties:
- $SO_{2}$ when passed through water forms a solution of sulphurous acid: $SO_{2(g)} + H_{2}O_{(l)} \rightleftharpoons H_{2}SO_{3(aq)}$
- It reacts with $NaOH$ solution to form sodium sulphite,which reacts with more $SO_{2}$ to form sodium hydrogen sulphite: $2NaOH + SO_{2} \rightarrow Na_{2}SO_{3} + H_{2}O$; $Na_{2}SO_{3} + H_{2}O + SO_{2} \rightarrow 2NaHSO_{3}$
- $SO_{2}$ reacts with chlorine in the presence of charcoal (catalyst) to give sulphuryl chloride: $SO_{2(g)} + Cl_{2(g)} \rightarrow SO_{2}Cl_{2(l)}$
- In the presence of vanadium$(V)$ oxide,it oxidizes to $SO_{3}$: $SO_{2(g)} + \frac{1}{2}O_{2(g)} \xrightarrow{V_{2}O_{5}} SO_{3(g)}$
- Moist sulphur dioxide acts as a reducing agent: $2Fe^{3+} + SO_{2} + 2H_{2}O \rightarrow 2Fe^{2+} + SO_{4}^{2-} + 4H^{+}$; $5SO_{2} + 2MnO_{4}^{-} + 2H_{2}O \rightarrow 5SO_{4}^{2-} + 4H^{+} + 2Mn^{2+}$
Uses:
- In the refining of petroleum and sugar.
- In the bleaching of wool and silk.
- As an anti-chlor,disinfectant,and preservative.
- Industrial chemicals such as $H_{2}SO_{4}$,$NaHSO_{3}$,and $Ca(HSO_{3})_{2}$ are prepared from $SO_{2}$.
- Liquid $SO_{2}$ is used as a solvent to dissolve a number of inorganic and organic chemicals.