(a) (i) Draw the abbreviated structural formula, in truncated form, of the compound that would be produced from the reaction of one molecule of glycerol with one molecule each of A, B and C .Circle and name the new functional group(s) produced. What type of reaction is represented by the reactions of A, B, and C with glycerol, and what other product is generated by these reactions?
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A CH3 -(CH2)7 -CH2 -C -OH
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B CH3- (CH2)15- CH2- C -OH
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C CH3- (CH2)7- CH= CH -(CH2)6- CH2- C- OH
Figure 4 Compounds, A, B and C. (ii) Explain, in terms of the type of molecule you have drawn, its chemical bonding and potential interaction with water, why the compound with the molecular structure you have drawn in part (a)(i) is not soluble in water. (
(b) Glycerol reacts with nitric acid (HNO3) to produce a colourless liquid, Compound D (Reaction 1). This reaction is undertaken in the presence of a catalyst (sulfuric acid, H2SO4).
C3 HO (l) + 3HNO3 (l) <=>C3 H3 (NO3 )3 (l) + 3H2 O(l) ΔH =− 364 kJ mol−1 (1)
Compound D
(i) State whether Reaction 1 is exo- or endothermic and draw a fully labelled diagram to show how the internal energy changes during the process represented by Reaction 1. Indicate the energy barrier for the reaction.
(ii) Explain the role of sulfuric acid in terms of the energy barrier of Reaction 1.
(iii) Reaction 1 is used commercially, but the vessel in which it is undertaken is cooled to maintain a steady temperature of 22 °C. Assuming Reaction 1 is reversible, as indicated, explain, in terms of Le Chatelier’s principle and the product yield, why this cooling is required.
(iv) When Reaction 1 is complete, Compound D can only be isolated once the acids have been removed. This is achieved by adding a strong base (sodium hydroxide, NaOH(aq)).
Explain what is meant by a strong base . Write balanced chemical equations, including state symbols, to illustrate (1) the reaction that occurs when solid sodium hydroxide is dissolved in water and (2) the reaction that occurs when sodium hydroxide solution is added to sulfuric acid. What type of reaction is represented by the equation you have written in (2)?
(c) Compound D decomposes rapidly to produce nitrogen, carbon dioxide, water vapour, oxygen and heat energy according to Reaction 2, with an energy change known as the enthalpy of decomposition. The temperature of this reaction can exceed 5000 °C.
4C3 H5 (NO3 )3 (l) = 12CO2 (g) + 10H2 O(g) + 6N2 (g) +O2 (g) + heat (2)
3533 22 22
Calculate the volume occupied by the gaseous products from the complete decomposition of 4 moles of Compound D, as shown in Reaction 2, when cooled to 25 °C and at atmospheric pressure.
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