Ethanol is manufactured by reacting ethene with steam in an exothermic reversible reaction. A phosphoric acid catalyst and a temperature of about 300 ∘C300\,^\circ\mathrm{C}300∘C are used.
Why is a much higher temperature not used?
The reaction would become slower, because heating opposes an exothermic forward reaction.
The catalyst would increase the yield only at about 300 ∘C300\,^\circ\mathrm{C}300∘C.
The reversible reaction would become one-way towards ethene and steam.
The reaction would be faster, but the equilibrium yield of ethanol would be lower.
136 exam-style questions on OCR GCSE Chemistry 6.1 Improving processes and products, covering 6.1.1 Extracting metals industrially and by electrolysis, 6.1.2 Life cycle assessment and recycling, 6.1.3 Biological methods of metal extraction, 6.1.4 The Haber process and the production of fertilisers, 6.1.5 Alloys and their uses, 6.1.6 Corrosion and its prevention, 6.1.7 Comparing and selecting materials, and 6.1.8 Industrial conditions, rate and position of equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.