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Sulfuric acid is manufactured by the Contact process - CIE - A-Level Chemistry - Question 1 - 2018 - Paper 1
Question 1
Sulfuric acid is manufactured by the Contact process. One stage in this process is the conversion of sulfur dioxide into sulfur trioxide in the presence of a heterog... show full transcript
Worked Solution & Example Answer:Sulfuric acid is manufactured by the Contact process - CIE - A-Level Chemistry - Question 1 - 2018 - Paper 1
Step 1
State the effect of a catalyst on a reaction. Explain how a catalyst causes this effect.
Answer
A catalyst is a substance that speeds up a reaction by creating an alternative pathway (mechanism) with lower activation energy. This allows for more frequent successful collisions between reactant molecules.
Step 2
Step 3
Use the data to calculate a value for the S=O bond energy in SO₃.
Answer
To find the bond energy of S=O in SO₃, we can use Hess's Law. Given that the enthalpy change ∆H = -196 kJ mol⁻¹ for the reaction, we have:
Using the bond energies:
over simplifying, we can find:
S=O bond energy in SO₃ = 2628 kJ mol⁻¹ + 471.3 kJ mol⁻¹ - 196 kJ mol⁻¹ = 534 kJ mol⁻¹.
Step 5
Step 6
Step 7
State and explain the effect of increasing temperature on the rate of production of SO₃.
Answer
Increasing temperature increases the rate of production of SO₃ because higher temperature gives more kinetic energy to the reactant molecules. This leads to an increased number of effective collisions per unit time, resulting in a higher rate of successful reactions.
Step 8
State and explain the effect of increasing temperature on the yield of SO₃.
Answer
Increasing temperature shifts the equilibrium increasingly to the left (towards reactants) for exothermic reactions, thus decreasing the yield of SO₃. Le Chatelier's principle implies the reaction favors the direction that absorbs heat in response to the change in temperature.
Step 9
Step 10
Complete the ‘dot-and-cross’ diagram to show the bonding in a molecule of SO₂. Show outer electrons only.
Answer
The dot-and-cross diagram for SO₂ should show one sulfur atom with six outer shell electrons and two oxygen atoms each with six outer shell electrons. Shared pairs of electrons between sulfur and oxygen represent the covalent bonds.
Step 11
Step 12