Discuss the application of Le-Chatlier's principle for the industrial synthesis of Sulphur trioxide (SO3).

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> [!TLDR]
> Le Chatelier's principle predicts the conditions (pressure, temperature, excess reactant) that maximize the industrial yield of $	ext{SO}_3$ from $	ext{SO}_2$ and $	ext{O}_2$.
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> **The equilibrium (Contact process):**
> $$2	ext{SO}_2(g) + 	ext{O}_2(g) ightleftharpoons 2	ext{SO}_3(g) \quad \Delta H = -197\ 	ext{kJ mol}^{-1}\ (	ext{exothermic})$$
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> **Le Chatelier's principle:** if a system at equilibrium is subjected to a change (in concentration, pressure, or temperature), the equilibrium shifts in the direction that tends to counteract that change.
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> **Applying it to this reaction:**
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> 1. **Effect of pressure:** the forward reaction decreases the number of gas moles (3 mol reactants → 2 mol product). By Le Chatelier's principle, increasing pressure shifts equilibrium in the direction of fewer moles, i.e., forward, favouring $	ext{SO}_3$ formation. So the process is run at high pressure.
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> 2. **Effect of temperature:** since the forward reaction is exothermic, Le Chatelier's principle predicts that lowering the temperature shifts equilibrium forward (favouring $	ext{SO}_3$), maximizing yield. However, too low a temperature makes the rate of reaction too slow to be industrially useful. So a compromise, moderately optimum temperature of about 700 K (~400–450°C) is used, along with a catalyst, to get a reasonably fast rate without sacrificing too much yield.
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Q.Discuss the application of Le-Chatlier's principle for the industrial synthesis of Sulphur trioxide (SO3).

Concept understanding — Le Chatelier's Principle

Le Chatelier's Principle

Q.Discuss the application of Le-Chatlier's principle for the industrial synthesis of Sulphur trioxide (SO3).

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