discuss the application of lechatelier principal for the industrial synthesis of sulphur dioxide
Answers
Le Chatelier's principle can be used to predict the behavior of a system due to changes in pressure, temperature, or concentration. Le Chatelier's principle implies that the addition of heat to a reaction will favor the endothermic direction of a reaction as this reduces the amount of heat produced in the system.
pplication of Le Chatelier's principle to
`N_(2_((g)))+3H_(2_((g)))hArr 2NH_(3_((g))),DeltaH=-92kJ`
1. Effect of pressure: Increase of external pressure on the reaction at equilibrium favours the reaction in the direction in which the volume or the number of moclecules decreases.
In the above reaction of formation of ammonia forward reaction involves decrease in volume or number of molecules.
So high pressure is avourable for the formation of ammonia. Hence ammonia is manufactured at 200 atm pressure.
2. Effect of temperature: In a reversible reaction if the forward reaction is exothermic, the backward reaction will be endothermic. High temperature favours the endothermic reaction while low temperature favours the exothermic reaction. Since the formation of ammonia is exothermic reaction low temperature is gavourable for the manufacture of ammonia. But at low temperature the reaction is slow. So an optinum temperature of about 725-755 K is used.
3. Effect of catalyst: To increase the rate of formation of ammonia iron powder mixed with molybdenum powder is used as catalyst. Molybdenum acts as promoter to iron catalyst.
4. Effect of concentration: Increase in concentrations of reactants increases the rate of forward reaction. Removal of the products from reaction mixture decreases the rate of backward reaction. So more ammonia can be obtained by increasing the concentration of `N_(2)` and `H_(2)` and removing the `NH_(3)` formed at regular intervals.
Optimum conditions for the synthesis of ammonia are
Pressure `=200` atm
Temperature `=725-755K`
Catalyst `=` Fe
Promoter `=` Mo
Application of Le Chatelier's principle to
`2SO_(2_((g)))+IO_(2_((g)))hArr2SO_(3_((g)))+`Heat
Effect of pressure : Increase of external pressure on the reaction at equilibrium favours the reaction in the direction in which the volume or the number of molecules decreases.
Formation of `SO_(3)` in the above reaction involved decreases involume. According to LeChatelier's principle high pressure is favourable for the formation of `SO_(3)`. So `SO_(3)` is prepared at a pressure of 1.5 to 1.7 atmospheres.
Effect of temperature: In a reversible reaction if the foward reaction is exothermic the backward reaction is endothermic. High temperatures are favourable for the endothermic reaction while the low temperatures are favourable for the exothermic reactions.
Since the formation of `SO_(3)` is exothermic reaction low temperatures are favourable. So `SO_(3)` is prepared at a temperature of about 673 K.
Effect of catalyst: To increase the rate of formation of `SO_(3)` catalyst like `V_(2)O_(5)` or platinised asbestos is used.
Effect of concentration: Increase in the concentration of the reactants increases the rate of forward reaction. Removal of products from reaction mixture decreases the rate of backward reaction. So more `SO_(3)` can be obtained by increasing the concentrations of `SO_(2)` and `O_(2)` and by removing the `SO_(3)` formed at regular intervals.
Optimum conditions for the synthesis of ammonia are
Pressure: `1.5-1.7` atmospheres
Temperature: `673K`
Catalyst: `V_(2)O_(5)` or Platinished asbestos.