Chemical synthesis — Question 25

QUESTION 25 (7 marks)

During the contact process for manufacturing sulfuric acid, sulfur dioxide (SO₂) and oxygen (O₂) are passed over a vanadium oxide catalyst to produce sulfur trioxide (SO₃). In the process, the vanadium oxide undergoes the following reactions.

Reaction 1:

$\mathrm{SO}_{2}\mathrm{(g)}+\mathrm{V}_{2}\mathrm{O}_{5}(s) \rightarrow SO_{3}\mathrm{(g)}+\mathrm{V}_{2}\mathrm{O}_{4}\mathrm{(s)}$

Reaction 2:

$\mathrm{2V}_{2}\mathrm{O}_{4}\mathrm{(s)}+\mathrm{O}_{2}(g) \rightarrow 2V_{2}\mathrm{O}_{5}\mathrm{(s)}$

25V O (s)2232SO (g)O (g)2SO (g)+→

Overall reaction:

(a) Determine the oxidation state of vanadium in V₂O₄(s).

[1 mark]

(b) Determine if vanadium in V₂O₅(s) in reaction 1 is acting as an oxidising or reducing agent. Explain your reasoning.

[2 marks]

(c) Use the reactions provided to explain why V₂O₅(s) is a catalyst for the overall reaction.

[4 marks]