Compounds P, Q and R have all been found in the atmosphere of one of Saturn's moons. P N≡C—C≡C—C≡N Q H—C≡C—C≡N R H | H—C—C≡N | H [Figure 3.PQR_structures]

1. (a)(i)The enthalpy change of formation, ∆Hᵣ, of CO₂(g) is −384 kJ mol⁻¹. Calculate the enthalpy change of formation, ∆Hᵣ, of P, in kJ mol⁻¹. ∆Hᵣ of P =[2]
2. (a)(ii)One of the products of the complete combustion of P is nitrogen gas, N₂(g). Explain the lack of reactivity of nitrogen.[1]
3. (b)(i)Ethyne, HCN and Q are all weak Brønsted-Lowry acids. Explain what is meant by the term weak Brønsted-Lowry acid.[2]
4. (b)(ii)Ethyne, HCN and Q all contain triple bonds between two atoms. A triple bond consists of one sigma (σ) and two pi (π) bonds. Draw a labelled diagram to show the formation of one pi (π) bond.[2]
5. (c)P and Q can be detected in the atmosphere by infrared spectroscopy. Identify two absorptions, and the bonds that correspond to these absorptions, that will appear in the infrared spectra of both P and Q. 1 2[2]
6. (d)(i)Name the type of reaction shown in reaction 1.[1]
7. (d)(ii)Draw the structure of S, the organic product of reaction 2.[1]
8. (d)(iii)Name T.[1]
9. (d)(iv)T can also be formed by the reaction of CH₃CH₂CH₂Br with ammonia. State the necessary conditions of this reaction.[1]

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