2024 XMS P2 PRELIM MS

3 XMSS/Chemistry/6092/02/Preliminary Examination 2024 Section A Answer all questions. 1 Choose from the following substances to answer the questions. A aluminium oxide, Al2O3 B carbon monoxide, CO C potassium dichromate(VI), K2Cr2O6 D ammonium nitrate, NH4NO3 E potassium manganate(VII), KMnO4 F fluorine, F2 G nitrogen dioxide, NO2 Use the letters A, B, C, D, E, F and G to answer the following questions. Each letter may be used once, more than once or not at all. Write the symbol for the substance which (a) is a neutral oxide. …………….. [1] (b) is able to oxidise iodide ions to iodine. …………….. [1] (c) produces an alkaline gas when warmed with sodium hydroxide. …………….. [1] (d) contains a transition metal with an oxidation state of +6. …………….. [1] (e) is soluble in rainwater, forming acid rain. …………….. [1] [Total: 5]

4 XMSS/Chemistry/6092/02/Preliminary Examination 2024 2 The reaction between ammonium perchlorate, NH 4ClO4, and aluminium metal is used to propel space shuttles. The reaction produces many substances such as steam and nitrogen gas. The equation shown below represents the reaction. ….. NH4ClO4 (s) + 10Al (s) → ….. Al2O3 (s) + 2AlCl3 (s) + ….. H2O (g) + 3N2 (g) (a) Balance and complete the equation by filling in the blanks. [1] (b) Calculate the oxidation state of chlorine in perchlorate ion, ClO4−. [2] (c) The reaction between aluminium and ammonium perchlorate is a redox reaction. State the role of aluminium in the redox reaction. Explain your reasoning , using changes in oxidation states of aluminium and chlorine. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… [3] (d) Complete the energy profile diagram for this exothermic reaction. You diagram should show and label • ‘products’ of the reaction, • the activation energy, Ea, • the enthalpy change, H, of reaction. [3] [Total: 9] energy reactants progress of reaction

5 XMSS/Chemistry/6092/02/Preliminary Examination 2024 3 Proteins and PET are polymers made by condensation polymerisation. (a) The diagram in Fig. 3.1 shows the structure of a section of protein. Fig. 3.1 (i) Draw a ‘dot-and-cross’ diagram of the molecule that is removed during the polymerisation of proteins. Show outer electrons only. [2] (ii) Proteins are polyamides. Name one other example of a polyamide. ……………………………………………………………………………………. [1] (b) PET is a polymer used to make plastic bottles. The diagram in Fig. 3.2 shows the structure of PET. Fig. 3.2 (i) Name the linkage present in PET. ……………………………………………………………………………………. [1] (ii) Draw the structure of one of the monomers used to produce PET. [1]

6 XMSS/Chemistry/6092/02/Preliminary Examination 2024 (iii) Describe one environmental issue arising from excessive use of plastics and one method in which plastics can be recycled. Issue: ……………………………………………………………………………. ……………………………………………………………………………………. ……………………………………………………………………………………. Method : …………………………………………………………………………. ……………………………………………………………………………………. ……………………………………………………………………………………. [1] [1] (c) Poly(ethene) is a polymer that is made by addition polymerisation. Describe two differences between addition polymerisation and condensation polymerisation. difference 1: ……………………………………………………………………………. …………………………………………………………………………………………… …………………………………………………………………………………………… difference 2: ……………………………………………………………………………. …………………………………………………………………………………………… …………………………………………………………………………………………… [1] [1] [Total: 9]

7 XMSS/Chemistry/6092/02/Preliminary Examination 2024 4 Sue investigates the reaction of small pieces of zinc with dilute hydrochloric acid at 25°C. The dilute hydrochloric acid is in excess. Fig. 4.1 shows the volume of hydrogen released as the reaction proceeds. Fig. 4.1 (a) Write a chemical equation, including state symbols, for the reaction. …………………………………………………………………………………………… [2] (b) Calculate the mass of zinc used in the reaction. mass = …………… g [2] (c) From Fig. 4.1, how long did it take for half the mass of zinc to be used up? …………………………………………………………………………………………… [1] (d) Sketch, on Fig. 4.1, the graph Sue will get if she repeats the experiment with hydrochloric acid in excess, but with half the mass of zinc used, in powdered form. Label this graph as ‘experiment 2’. [2] [Total: 7]

8 XMSS/Chemistry/6092/02/Preliminary Examination 2024 5 Dilute methanoic acid reacts with aqueous calcium hydroxide. 2HCOOH + Ca(OH)2 → (HCOO)2Ca + 2H2O (a) Write an ionic equation for this neutralisation reaction between methanoic acid and calcium hydroxide. …………………………………………………………………………………………… [1] (b) (c) Deduce the general equation for the reaction of methanoic acid with Group 2 metals. Use M as the symbol for a Group 2 metal. …………………………………………………………………………………………… Methanoic acid is a weak acid. It dissociates partially in water, producing methanoate ions and hydrogen ions, as shown. HCOOH (aq) HCOO− (aq) + H+ (aq) [1] (i) How does the equation show that methanoic acid is a weak acid? ……………………………………………………………………………………. [1] (ii) Complete Fig. 5.1 to show the arrangement of the electrons, in the outer shells, for carbon and oxygen, in a methanoate ion. Electrons of hydrogen ( ) have been completed for you. You should use the symbols provided for each element in the key. Fig. 5.1 [3] [Total: 6] key C H O C H O O −

9 XMSS/Chemistry/6092/02/Preliminary Examination 2024 6 Solvents made up of different mixtures of ethanol and water were used to separate the dyes in a sample of black ink. The black ink contains a mixture of blue , red and yellow dyes. The coloured dyes have different R f values in solvents with different compositions of ethanol as shown in Fig. 6.1 below. Fig. 6.1 (a) Which coloured dye in black ink is insoluble in a solvent containing 100% ethanol? …………………………………………………………………………………………… [1] (b) From Fig. 6.1, which percentage by volume of ethanol cannot be used to separate all the dyes in black ink? ……………. % Explain your answer. …………………………………………………………………………………………… …………………………………………………………………………………………… [1] [1] (c) What is the R f value of the blue dye, when the solvent is made up of 96 cm 3 ethanol and 104 cm3 water? Show your working clearly. [2] [Total: 5] Percentage by volume of ethanol

10 XMSS/Chemistry/6092/02/Preliminary Examination 2024 7 The reactivity series of metals can be compared by their reactions with water, steam and displacement reactions. Some data of these experiments are recorded in Table 7.1 below. Table 7.1 Metals Reaction with water Reaction with steam Displacement reactions Mercury No visible change. No visible change. Silvery metal remains unchanged. No visible change. Magnesium Slow reaction Metal burns in steam. Grey solid turns white. Displaces zinc from Zn(NO3)2 (aq) Iron No visible change. Reacts slowly with steam. Silvery solid turns black. Displaces mercury from aqueous Hg(NO3)2 (aq) Zinc No visible change. Reacts slowly with steam. Grey solid turns yellow when hot. Displaces iron from Fe(NO3)2 (aq) (a) Arrange the metals in Table 7.1, from least reactive to most reactive. …………………………