Making ethanol by the hydration of ethene
4 marks · NormalState the temperature used in the hydration of ethene.
Give the pressure (in atmospheres) required for this reaction.
Name the catalyst used in the hydration of ethene.
Explain why these conditions (temperature and pressure) are used in industry for this reaction.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 300°C
(b) 60–70 atmospheres
(c) phosphoric acid (H3PO4)
(d) To increase reaction rate and yield; high temperature speeds up the reaction, high pressure increases ethene and steam collisions, but conditions are balanced to optimise both yield and cost. · must show increase rate, increase yield, balance yield and cost
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States correct temperature used: 300°C (accept 290–310°C).
B2 (b) · 1 mark · States correct pressure: 60–70 atmospheres (accept 60, 65, 70 atm).
B3 (c) · 1 mark · Correctly names catalyst: phosphoric acid or H3PO4.
B4 (d) · 1 mark · Correctly explains the conditions are used to achieve a compromise between yield and rate, or between efficiency and cost (both points needed for mark).
Worked solution
(a) 300°C
(b) 60–70 atmospheres
(c) Phosphoric acid (H3PO4)
(d) These conditions are used so the reaction is fast and high yielding without being too expensive. High temperature and pressure speed up reactions and increase yield, but are balanced to avoid unnecessary costs.