Sulfur trioxide (SO3\text{SO}_3SO3) is produced industrially by reacting sulfur dioxide (SO2\text{SO}_2SO2) with oxygen (O2\text{O}_2O2) at a temperature of 450∘C450^\circ\text{C}450∘C and a pressure of 2 atm2\text{ atm}2 atm. Under these conditions, the percentage yield of sulfur trioxide is approximately 96%96\%96%.
The chemical equation for this reversible reaction is:
2SO2(g)+O2(g)⇌2SO3(g)ΔH=−197 kJ/mol 2\text{SO}_2\text{(g)} + \text{O}_2\text{(g)} \rightleftharpoons 2\text{SO}_3\text{(g)} \quad \Delta H = -197\text{ kJ/mol} 2SO2(g)+O2(g)⇌2SO3(g)ΔH=−197 kJ/mol(i) State what the symbols ⇌\rightleftharpoons⇌ and ΔH\Delta HΔH represent.
(ii) Name the catalyst used in this industrial process.
(i) Predict the effect on the yield of sulfur trioxide if the reaction is carried out at a temperature higher than 450∘C450^\circ\text{C}450∘C, but at the same pressure of 2 atm2\text{ atm}2 atm. Assume the reaction reaches equilibrium. Give a reason for your answer.
(ii) Predict the effect on the yield of sulfur trioxide if the reaction is carried out at a pressure higher than 2 atm2\text{ atm}2 atm, but at the same temperature of 450∘C450^\circ\text{C}450∘C. Assume the reaction reaches equilibrium. Give a reason for your answer.
One method of obtaining sulfur dioxide is by burning sulfur extracted from underground deposits. Sulfur dioxide can also be produced by the thermal decomposition of calcium sulfate minerals. The equation for this alternative reaction is:
2CaSO4(s)→heat2CaO(s)+2SO2(g)+O2(g) 2\text{CaSO}_4\text{(s)} \xrightarrow{\text{heat}} 2\text{CaO(s)} + 2\text{SO}_2\text{(g)} + \text{O}_2\text{(g)} 2CaSO4(s)heat2CaO(s)+2SO2(g)+O2(g)(i) State the type of reaction taking place.
(ii) Suggest why it may be necessary, in the future, to obtain sulfur dioxide using alternative methods or minerals rather than extracting underground sulfur deposits.
