Chemistry Questionnaire Essay

What is meant by the circumstance cis-trans isomerism? How many cis-trans isomers argon present in Structure I? operate any 2 possible cis-trans isomers. (iii) State the physical say of this lipoid at room temperature. Explain your answer. 9 (b) adumbrate a possible personal identity for each of the organic compounds A-E below. Explain your reasoning and write balanced equations for the receptions relate 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 non 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 on a lower floor reflux with sedimentary potassium manganate(VII), D gives a compound, E, C4H6O3. E reacts with alkaline aqueous unity to give a yellow precipitate and evolves carbon dioxide when solid sodium carbonate is added.Draw structural formulae of the products of th e reactions mingled with glutamic acid and I aqueous NaOH II aqueous HCl (ii) Draw the structural formula of a dipeptide form between glutamic acid and phenylalanine, showing the ionic form in which it would experience at pH 10. 4 Total 20 5 3 (a) Iron(III) chloride is a dark brownness solid which dissolves in water to give an acidic base. This solution is use 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) implement 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 general E0 value if the thickness of the copper coating is join ond.Anhydrous aluminium chloride behaves in addition as anhydrous iron(III) chloride in that they sub lime readily when heated. When 1. 56 g of aluminium chloride was placed in an evacuated vessel of volume 1. 00 dm3 at 1800C, the jam 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 parti onlyy 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, great(p) a reason in each case, the effect on the equilibrium of dimer in the equilibrium mixture if I the pressure is lowered, II the temperature is lowered.MgO(s) + CO2(g) ?H? = +117 kJ mol-1 ?S? = +175 J mol-1 K-1 8 (i) Why does the entropy increase when milligram carbonate decomposes? (ii) Calculate the standard Gibbs free energy variety show, ? G? , for the decomposition of magnesium carbonate. Comment on the spontaneity of the decomposi tion of magnesium carbonate at room temperature. (iii) Assuming that ? H? and ? S? for the reaction are independent of temperature, calculate the temperature at which the decomposition reaction becomes feasible. (iv) examine the ease of thermal decomposition of magnesium carbonate with barium carbonate. 8 make for over 4 (d) Suggest a simple chemical examen to distinguish between each pair of compounds. For each test, give reagents and conditions, and state what would be seen with each compound.The dissociation reactions and Ka values of carbonic acid are given below. H2CO3 HCO3- + H+ Ka1 = 4. 2 x 10-7 mol dm-3 HCO3- CO32 + H+ Ka2 = 4. 8 x 10-11 mol dm-3 0. 10 mol dm-3 aqueous NaOH is added slowly to 20. 0 cm3 of carbonic acid and the change in pH is followed and shown below. pH x x B x A x x 10 20 30 40 10 Vol of aqueous NaOH added / cm3 (i) Calculate the initial pH of the carbonic acid, stating any assumptions you make. (ii) Calculate the pH at the start equivalence point, A. (iii) What is the pH at point B? Give a reason for your answer. 6 Turn over 5 (b) Maintenance of pH is vital to the cells of all living organisms because enzyme activity is influenced by pH. For instance, protection from harmful pH change in the blood plasma is provided by the hydrogencarbonate/carbonic acid strategy (HCO3-/H2CO3). At 370C, the temperature of the human body, pH of blood plasma is 7. 4. i) Explain, with relevant equations, how the hydrogencarbonate/carbonic acid system regulates the pH of blood plasma. (ii) Calculate the ratio of HCO3-/H2CO3 for maintaining the optimal pH of blood plasma. 4 (c) Describe two differences in physical properties between transition metals and a s-block metal such as magnesium, suggesting reasons for these differences based on their atomic structures. 3 11 (d) The oxidation of manganese(IV) oxide in alkaline solution in air produces green manganate(VI) ion, MnO42-. When manganate(VI) is added to a dilute acid, a purple solution and dark brown solid manganese(IV) oxide reforms.