Chemistry Questionnaire

What is meant by the term cis-trans isomerism? How many cis-trans isomers are present in Structure I? Draw any 2 possible cis-trans isomers. (iii) State the physical state of this lipid at room temperature. Explain your answer. [9] (b) Suggest a possible identity for each of the organic compounds A-E below. Explain your reasoning and write balanced equations for the reactions involved where possible. i) A, C11H14O2 is a neutral compound. Hydrolysis of A gives B, C7H6O2 which is a white precipitate and C, C4H10O which does not decolourise acidified potassium manganate(VII) on heating. (ii) D, C4H10O2 reacts with 2 moles of sodium metal, but not with solid sodium carbonate. On boiling under reflux with aqueous potassium manganate(VII), D gives a compound, E, C4H6O3. E reacts with alkaline aqueous iodine to give a yellow precipitate and evolves carbon dioxide when solid sodium carbonate is added.

Draw structural formulae of the products of the reactions between glutamic acid and I aqueous NaOH II aqueous HCl (ii) Draw the structural formula of a dipeptide formed between glutamic acid and phenylalanine, showing the ionic form in which it would exist at pH 10. [4] [Total: 20] 5 3 (a) Iron(III) chloride is a dark brown solid which dissolves in water to give an acidic solution. This solution is used to etch, i. e. dissolve, unwanted copper from printed circuit boards. When a copper-coated printed circuit board is immersed in aqueous iron(III) chloride, the solution turns greenish blue. i) Explain, with the aid of an equation, why aqueous iron(III) chloride is acidic. (ii) Use the Data Booklet to explain why iron(III) chloride etches copper. Give a relevant equation to explain the greenish blue solution observed. (iii) Suggest what happens to the overall E0 value if the thickness of the copper coating is increased.

Anhydrous aluminium chloride behaves similarly as anhydrous iron(III) chloride in that they sublime readily when heated. When 1. 56 g of aluminium chloride was placed in an evacuated vessel of volume 1. 00 dm3 at 1800C, the pressure produced was 32. kPa. (i) Calculate the apparent relative molecular mass of the aluminium chloride under the stated conditions. (ii) In the vapour phase, aluminium chloride partially exists as a dimer. Using your answer obtained for b(i), calculate the percentage of the dimer under the stated conditions. (iii) Suggest a reason why the dimerisation process of aluminium chloride is exothermic. 6 (iv) Predict, giving a reason in each case, the effect on the proportion of dimer in the equilibrium mixture if I the pressure is lowered, II the temperature is lowered.