Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Chemical reactions of the alkenes
19 practice questions
Practice questions
11–19 of 19
Question 11
3 marks · Normal
Answer and see the solution →An alkene has 8 carbon atoms in its molecule.
Calculate the number of hydrogen atoms present in one molecule of this alkene. Show your working.
Question 12
3 marks · Normal
Answer and see the solution →Alkenes are described as unsaturated hydrocarbons.
Explain what 'unsaturated' means and how you can test for unsaturation using a chemical reaction.
Question 13
4 marks · Normal
Answer and see the solution →A student compares the combustion reactions of three alkenes. The table shows the number of carbon and hydrogen atoms in each.
Alkene Number of carbon atoms (n) Number of hydrogen atoms Ethene 2 4 Propene 3 6 Pentene 5 10 (a)[1 mark]State the general formula for alkenes.
(b)[2 marks]Explain the pattern between the number of carbon atoms and hydrogen atoms in these alkenes.
(c)[1 mark]Write the molecular formula for hexene.
Question 14
1 mark · Normal
Answer and check →Which statement best describes an addition reaction of ethene?
- A.Two ethene molecules join together to form a longer chain.
- B.Ethene reacts with oxygen to form carbon dioxide and water.
- C.Bromine atoms add across the double bond of ethene.
- D.Hydrogen atoms are lost from ethene forming ethyne.
Question 15
4 marks · Normal
Answer and see the solution →This question is about reactions of propene (C3H6).
(a)[1 mark]Explain why propene is classified as an unsaturated hydrocarbon.
(b)[1 mark]Write a word equation for the addition reaction of propene with hydrogen.
(c)[2 marks]Describe what is formed when propene burns in a plentiful supply of air.
Question 16
2 marks · Normal
Answer and see the solution →Alkenes are a family of unsaturated hydrocarbons that undergo two main types of chemical reactions: combustion and addition.
Describe what happens during:
(a)[1 mark](i) the combustion of an alkene in oxygen
(b)[1 mark](ii) an addition reaction of an alkene
Question 17
2 marks · Hard
Answer and see the solution →State the products formed when pentene (C5H10) undergoes complete combustion in oxygen. Write a balanced chemical equation for the reaction.
Question 18
5 marks · Hard
Answer and see the solution →This question is about reactions of hexene (C6H12).
(a)[2 marks]Describe what happens to the C=C double bond in an addition reaction of hexene.
(b)[2 marks]State the product formed when hexene reacts with hydrogen in an addition reaction. Suggest the molecular formula of the product.
(c)[1 mark]Write a chemical equation for the complete combustion of hexene.
Question 19
2 marks · Hard
Answer and see the solution →Give a general description of what happens to an alkene during a combustion reaction. Explain why alkenes are not normally used as fuels.