Ethene can undergo addition reactions with several different reagents. Describe what happens when ethene reacts with steam, including the conditions required and the name of the product formed.

Edexcel GCSE Chemistry (1CH0) — 10.2 Alkenes (Chem only) · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Ethene reacts with steam (water) in the presence of a catalyst such as phosphoric acid (H3PO4) and under high temperature and pressure.

The double bond of ethene is broken, allowing the addition of two –OH groups.

The product formed is ethanol (CH3CH2OH).

Examiner tips

  • Use the word ‘addition’ to show the double bond is broken. Mention the catalyst (H3PO4) and the need for high temperature/pressure. State the product as ethanol. Keep the answer concise and use correct chemical names.

Common mistakes

  • Writing ‘ethane’ instead of ‘ethanol’. Omitting the catalyst or the high temperature/pressure condition. Using ‘hydrogenation’ instead of ‘addition of water’.

Mark scheme (4 marks)

  1. High temperature/pressure is required as a condition
  2. A catalyst (phosphoric acid / H3PO4) is required
  3. The C=C double bond in ethene breaks / opens up (addition reaction)
  4. The product formed is ethanol

Key terms in this question

addition reaction

Related

More Alkenes (Chem only) questions

▶ Try answering this question with AI marking (free) →