Chemistry 0620/42 October/November 2020: question paper and mark scheme

Question

The electronic structures of some atoms and ions are shown. A B C D 2+ 3– + E F G H – – (a) Write the letters, A, B, C, D, E, F, G or H, of the electronic structures which show: (i) atoms of two different noble gases …… and �������������������������������������� [2] (ii) an ion of a Group I element …… [1] (iii) an ion of a Group V element . …… [1] (iv) a pair of ions that could form a compound with the formula XY2. …… and …… [1] (b) State which electronic structure, A, B, C, D, E, F, G or H, is incorrect. Explain why. explanation …… . …… [2] (c) State how many protons are found in the nucleus of ion C. …… [1] (d) Use the Periodic Table to deduce: (i) the chemical symbol for ion G …… [1] (ii) the element which forms an ion with a 3+ charge and the same electronic structure as H. . …… [1] [Total: 10]

Question

Soluble salts can be made by adding a metal carbonate to a dilute acid. (a) Give the formula of the dilute acid which reacts with a metal carbonate to form a nitrate salt. . …… [1] (b) A student wanted to make hydrated iron(II) sulfate crystals, FeSO4•xH2O, by adding excess iron(II) carbonate to dilute sulfuric acid. The student followed the procedure shown. step 1 Add dilute sulfuric acid to a beaker. step 2 Add small amounts of iron(II) carbonate to the dilute sulfuric acid in the beaker until the iron(II) carbonate is in excess. step 3 Filter the mixture formed in step 2. step 4 Heat the filtrate until it is a saturated solution. Allow to cool. step 5 Once cold, pour away the remaining solution. Dry the crystals between filter papers. (i) Why must the iron(II) carbonate be added in excess in step 2? . …… [1] (ii) State two observations in step 2 that would show that iron(II) carbonate was in excess. 1 . …… 2 . …… [2] (iii) Describe what should be done during step 3 to ensure there is a maximum yield of crystals. . …… [1] (iv) A saturated solution is formed in step 4. Describe what a saturated solution is. . …… . …… [2] (v) Name a different compound that could be used instead of iron(II) carbonate to produce hydrated iron(II) sulfate crystals from dilute sulfuric acid. . …… [1] (c) On analysing the crystals, the student found that one mole of the hydrated iron(II) sulfate crystals, FeSO4•xH2O, had a mass of 278 g. Determine the value of x using the following steps: ●● calculate the mass of one mole of FeSO4 mass = …… g ●● calculate the mass of H2O present in one mole of FeSO4•xH2O mass of H2O = …… g ●● determine the value of x. x = …… [3] (d) Insoluble salts can be made by mixing solutions of two soluble salts. A student followed the procedure shown to make silver bromide, an insoluble salt. step 1 Add aqueous silver nitrate to a beaker. Then add aqueous potassium bromide and stir. step 2 Filter the mixture formed in step 1. step 3 Dry the residue. (i) State the term used to describe this method of making salts. . …… [1] (ii) Give the observation the student would make during step 1. . …… [1] (iii) Write the ionic equation for the reaction between aqueous silver nitrate and aqueous potassium bromide. Include state symbols. . …… [3] (e) Sodium chloride is an ionic salt. It can be made by reacting sodium with chlorine gas. The equation for this reaction is shown. 2Na(s) + Cl 2(g) → 2NaCl (s) Calculate the volume of chlorine gas, in cm3, that reacts to form 2.34 g of NaCl . The reaction takes place at room temperature and pressure. volume of chlorine gas = …… cm3 [3] (f) Sodium chloride does not conduct electricity when solid, but does conduct electricity when molten. (i) Explain why, in terms of structure and bonding. . …… . …… . …… . …… [3] (ii) Name the product formed at the positive electrode when electricity is passed through molten sodium chloride. . …… [1] (iii) State the type of change that occurs at the positive electrode in (ii). Explain your answer in terms of electron transfer. type of change …… explanation …… [2] (iv) Describe what else can be done to sodium chloride to allow it to conduct electricity. . …… [1] [Total: 26]

Question

Group I metals are very reactive. Transition elements are also metals but are less reactive than Group I metals. (a) State two physical properties of Group I metals which are similar to those of transition metals. 1 . …… 2 . …… [2] (b) Describe two ways in which the physical properties of Group I metals are different from those of transition metals. 1 . …… . …… 2 . …… . …… [2] (c) When Group I metals are added to water they fizz and an alkaline solution forms. (i) Name the gas given off. . …… [1] (ii) Identify the ion present in the solution which makes the solution alkaline. . …… [1] (iii) Write the chemical equation for the reaction between sodium and water. . …… [2] (d) When the transition element iron is added to water the iron rusts. When an iron object is coated with a layer of zinc, rusting is prevented. (i) Name this process of coating iron objects with a layer of zinc. . …… [1] (ii) Explain how completely coating an iron object with a layer of zinc prevents rusting. . …… [1] (iii) Rusting of iron ships can be prevented by attaching zinc blocks to the hull of the ship. Explain how this prevents rusting. . …… . …… [2] [Total: 12]

Question

Alkenes and alkanes are homologous series of compounds containing carbon and hydrogen atoms. (a) State the name of the type of compound made from carbon and hydrogen atoms only. . …… [1] (b) Alkenes take part in addition reactions. (i) Describe what is meant by the term addition reaction. . …… [1] (ii) Draw the structure of the product made in the addition reaction between propene and bromine. Show all of the atoms and all of the bonds. [2] (iii) Describe the colour change seen when propene is added to aqueous bromine. from …… to …… [2] (iv) Draw the structures of molecules of two different alkenes which both undergo an addition reaction with steam to form butan-2-ol. Show all of the atoms and all of the bonds. [2] (c) Propane undergoes a substitution reaction with chlorine. Write the chemical equation for the reaction between one molecule of propane and one molecule of chlorine. . …… [2] [Total: 10]

Question

This question is about alcohols, carboxylic acids and esters. (a) Ethanol will react with hot aqueous potassium manganate(VII) to form ethanoic acid. (i) State the other condition needed for this reaction to take place. . …… [1] (ii) State the type of chemical change that happens to the ethanol during this reaction. . …… [1] (iii) The structure of ethanoic acid is shown. H O H C C H O H Complete the dot-and-cross diagram to show the electron arrangement in a molecule of ethanoic acid. H O H C C H O H [3] (b) Ethanoic acid is a weak acid and hydrochloric acid is a strong acid. Complete the table to show the similarities and differences in the properties of samples of these two acids of equal concentration. dilute ethanoic acid dilute hydrochloric acid extent of dissociation colour after adding universal indicator solution observation when magnesium ribbon is added [6] (c) Ethanoic acid will react with an alcohol to form the ester shown. H H O H C H H C C O C H H H C H H (i) Name the other product formed when ethanoic acid reacts with an alcohol to make this ester. . …… [1] (ii) Give one condition needed when ethanoic acid reacts with the alcohol to make this ester. . …… [1] (iii) Draw the structure of the alcohol which was added to ethanoic acid to make this ester. Show all of the atoms and all of the bonds. [2] (d) Polyesters can be manufactured from carboxylic acids and alcohols. Hexanedioic acid has the structure: HOOC–CH2–CH2–CH2–CH2–COOH. This structure can be simplified as shown. O O H O C C O H Ethanediol has the structure: HO–CH2–CH2–OH. This structure can be simplified as shown. H O O H The functional groups are found at the end of each molecule. (i) State what is meant by the term functional group. . …… [1] (ii) Determine the empirical formula of hexanedioic acid. . …… [1] (iii) Calculate the percentage by mass of oxygen present in ethanediol. Give your answer to the nearest whole number. …… % [2] (iv) Complete the diagram to show a section of polyester manufactured from hexanedioic acid and ethanediol. Include all of the atoms and all of the bonds in the linkages. [2] (v) State the name of a polyester. . …… [1] [Total: 22] The Periodic Table of Elements Group I II III IV V VI VII VIII 1 2 H He hydrogen helium Key 1 4 3 4 atomic number 5 6 7 8 9 10 Li Be atomic symbol B C N O F Ne lithium beryllium name boron carbon nitrogen oxygen fluorine neon 7 9 relative atomic mass 11 12 14 16 19 20 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar sodium magnesium aluminium silicon phosphorus sulfur chlorine argon 23 24 27 28 31 32 35.5 40 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton 39 40 45 48 51 52 55 56 59 59 64 65 70 73 75 79 80 84 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon 12 85 88 89 91 93 96 – 101 103 106 108 112 115 119 122 128 127 131 55 56 57–71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 lanthanoids Cs Ba Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn caesium barium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium astatine radon 133 137 178 181 184 186 190 192 195 197 201 204 207 209 – – – 87 88 89–103 104 105 106 107 108 109 110 111 112 114 116 actinoids Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Cn Fl Lv francium radium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium flerovium livermorium – – – – – – – – – – – – – 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 lanthanoids La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium 139 140 141 144 – 150 152 157 159 163 165 167 169 173 175 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 actinoids Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium – 232 231 238 – – – – – – – – – – – The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.).