Cycloalkanes show similar chemical properties to alkanes but have the same empirical formula as alkenes.

1. (a)Define empirical formula.[1]
2. (b)Cyclopentane, C₅H₁₀, has four cyclic structural isomers. One of these isomers is C, shown in Fig. 3.1. Complete Fig. 3.1 to show two other cyclic structural isomers of C₅H₁₀. [Figure 3.1][2]
3. (c)Cyclopentane reacts with Cl₂ in the presence of ultraviolet light to form C₅H₉Cl.
4. (c)(i)The reaction is initiated by the bond fission of Cl₂. State the type of bond fission shown in the initiation step.[1]
5. (c)(ii)Complete the equations to show the two propagation steps that follow the initiation step. propagation 1 C₅H₁₀ + .......... → C₅H₉• + .......... propagation 2 C₅H₉• + .......... → C₅H₉Cl + ..........[2]
6. (c)(iii)The final step is shown. C₅H₉• + Cl• → C₅H₉Cl Give the name for this step in the reaction.[1]
7. (d)Fig. 3.2 shows a reaction cycle involving cyclopentane, cyclopentene and C₅H₉Cl. [Figure 3.2]
8. (d)(i)Identify a suitable reagent for reaction 3.[1]
9. (d)(ii)Use the data in Fig. 3.2 and in Table 3.1 to calculate the enthalpy change of reaction 2, ΔH₂. compound | enthalpy change of combustion, ΔHᶜ/kJ mol⁻¹ cyclopentane (structure) | -3292 cyclopentene (structure) | -3115 H₂ | -286 ΔH₂ = .......... kJ mol⁻¹[2]
10. (e)Cyclopentene, C₅H₈, reacts with hot concentrated acidified KMnO₄ to form compound W, C₅H₈O₄.
11. (e)(i)Draw the structure of W.[1]
12. (e)(ii)The infrared spectrum of W is shown in Fig. 3.3. [Figure 3.3] Identify two absorptions in the infrared spectrum of W that would not be present in the infrared spectrum of cyclopentene. • Write 1 or 2 on Fig. 3.3 against each of these two absorptions. • Complete Table 3.2 to show which bond is responsible for each absorption that you have identified in Fig. 3.3. absorption | 1 | 2 bond responsible | |[2]

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