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Part of the Contact Process for the manufacture of sulfuric acid involves the conversion of sulfur dioxide to sulfur trioxide, as shown by the equation $$2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g) \quad \Delta H = -192 \text{ kJ mol}^{-1}$$ As part of a laboratory study of this process, a container was filled with an equilibrium mixture of sulfur dioxide, sulfur trioxide and oxygen in the presence of a catalyst - VCE - SSCE Chemistry - Question 2 - 2003 - Paper 1
Question 2
Part of the Contact Process for the manufacture of sulfuric acid involves the conversion of sulfur dioxide to sulfur trioxide, as shown by the equation $$2SO_2(g) +... show full transcript
Worked Solution & Example Answer:Part of the Contact Process for the manufacture of sulfuric acid involves the conversion of sulfur dioxide to sulfur trioxide, as shown by the equation $$2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g) \quad \Delta H = -192 \text{ kJ mol}^{-1}$$ As part of a laboratory study of this process, a container was filled with an equilibrium mixture of sulfur dioxide, sulfur trioxide and oxygen in the presence of a catalyst - VCE - SSCE Chemistry - Question 2 - 2003 - Paper 1
Step 1
What change occurred at the 10 minute point?
Answer
At the 10 minute point, an addition of oxygen (O2) to the equilibrium mixture was made. This shift in equilibrium results in an increase in the concentration of sulfur trioxide (SO3) as the reaction proceeds to the right, favoring the formation of products.
Step 2
Step 3
Give explanations for the changes in concentration that occur in X, Y and O2 between 10 and 20 minutes.
Answer
Between 10 and 20 minutes, the addition of O2 shifts the equilibrium position to the right due to Le Chatelier's principle. Consequently, the concentration of X (SO2) will increase as it gets converted into Y (SO3). Meanwhile, the concentration of Y (SO3) will also increase as its production is favored, and the amount of O2 may decrease as it is consumed in the reaction.
Step 4
Would the temperature of the mixture increase, decrease or remain the same between 10 and 20 minutes? Explain your reasoning.
Answer
The temperature of the mixture would decrease between 10 and 20 minutes. This is because the forward reaction is exothermic, meaning that heat is released when SO2 and O2 react to form SO3. Therefore, any heat loss would result in a decrease in the temperature of the system.