Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Structural isomerism in the alkanes
19 practice questions
Practice questions
11–19 of 19
Question 11
3 marks · Normal
Answer and see the solution →A hydrocarbon has the molecular formula C6H14. How many structural isomers are possible for C6H14? Show your reasoning.
Question 12
3 marks · Normal
Answer and see the solution →Explain how you would decide whether two structures for C5H12 drawn below are isomers or not.
Structure 1: CH3–CH2–CH2–CH2–CH3 Structure 2: CH3–CH(CH3)–CH2–CH3
Question 13
4 marks · Normal
Answer and see the solution →The following table gives the molecular formulae and numbers of structural isomers possible for members of the alkane series:
Alkane Molecular formula Number of isomers Methane CH4 1 Ethane C2H6 1 Propane C3H8 1 Butane C4H10 2 Pentane C5H12 3 Hexane C6H14 ? (a)[1 mark]Compare the number of isomers as the number of carbon atoms increases from C4H10 to C6H14.
(b)[2 marks]Explain why the number of structural isomers increases as you go from C4H10 to C6H14.
(c)[1 mark]Use the data to predict the number of isomers for C6H14.
Question 14
1 mark · Normal
Answer and check →Which statement is true about structural isomers?
- A.They have the same molecular and structural formulae.
- B.They have the same atoms joined in a different order.
- C.They are different elements with the same mass number.
- D.They all have a straight chain structure.
Question 15
2 marks · Normal
Answer and see the solution →State one difference and one similarity between structural isomers.
Question 16
4 marks · Normal
Answer and see the solution →Heptane (C7H16) is an alkane. Answer the following about its isomers.
(a)[1 mark]Explain why heptane can form structural isomers.
(b)[2 marks]Draw the skeletal formula of two different isomers of C7H16.
(c)[1 mark]State one feature that all isomers of C7H16 share.
Question 17
2 marks · Hard
Answer and see the solution →Explain why two different molecules with the formula C6H14 are considered structural isomers.
Question 18
5 marks · Hard
Answer and see the solution →This question is about structural isomerism in the alkanes.
(a)[3 marks]Complete the following table for alkanes, giving the number of possible structural isomers for each formula.
Molecular formula Number of structural isomers C3H8 C4H10 C5H12 (b)[2 marks]Explain why C5H12 has more structural isomers than C3H8.
Question 19
2 marks · Hard
Answer and see the solution →Explain why it is not possible to have a structural isomer of methane (CH4).