Chemistry 0620/43 October/November 2020: question paper and mark scheme

Question

The names of nine substances are shown. aluminium oxide ammonia carbon monoxide anhydrous cobalt(II) chloride hydrated copper(II) sulfate iron(III) oxide nitrogen dioxide silver steel Answer the following questions using these substances. Each substance may be used once, more than once or not at all. Name the substance that is: [Total: 6]

Question

The table gives information about five particles, A, B, C, D and E. number of number of number of particle electrons neutrons protons A 10 13 11 B 18 20 18 C 18 18 18 D 10 12 8 E 10 10 10 (a) State the atomic number of A. . …… [1] (b) State the nucleon number of B. . …… [1] (c) Write the electronic structure of C. . …… [1] (d) Give the letters of all the particles which are: [Total: 7]

Question

This question is about nitrogen and some of its compounds. (a) Complete the dot-and-cross diagram to show the electron arrangement in a molecule of nitrogen, N2. Show the outer shell electrons only. N N [2] (b) Nitrogen can be converted into ammonia by the Haber process. (i) Describe how nitrogen is obtained for the Haber process. . …… . …… [2] (ii) Give the essential reaction conditions and write a chemical equation for the reaction occurring in the Haber process. chemical equation: . …… . …… reaction conditions: . …… . …… . …… . …… . …… [5] (c) Some of the ammonia made by the Haber process is converted into nitric acid. The first stage of this process is the oxidation of ammonia to make nitrogen monoxide. 4NH3(g) + 5O2(g) 4NO(g) + 6H2O(g) The process is carried out at 900 °C and a pressure of 5 atmospheres using an alloy of platinum and rhodium as a catalyst. The forward reaction is exothermic. (i) State the meaning of the term catalyst. . …… . …… [2] (ii) State the meaning of the term oxidation. . …… [1] (iii) Complete the table using the words increase, decrease or no change. effect on the rate effect on the equilibrium of the forward reaction yield of NO(g) increasing the temperature increasing the pressure [4] (d) Nitrogen monoxide, NO, is converted into nitrogen dioxide, NO2. 2NO(g) + O2(g) → 2NO2(g) The nitrogen dioxide reacts with oxygen and water to produce nitric acid as the only product. Write a chemical equation for this reaction. . …… [2] (e) Ammonium nitrate, NH4NO3, is a fertiliser. Calculate the percentage by mass of nitrogen in ammonium nitrate. …… % [2] [Total: 20]

Question

Zinc is manufactured from zinc blende. Zinc blende is an ore which consists mainly of zinc sulfide, ZnS. (a) Zinc blende is roasted in air. One of the products is zinc oxide. Name the other product formed in this reaction. . …… [1] (b) Zinc oxide is then converted into zinc. Zinc oxide and coke, a source of carbon, are heated in a furnace. Hot air is blown into the furnace. (i) Give two reasons why coke is needed. 1 . …… 2 . …… [2] (ii) Write a chemical equation for the formation of zinc in the furnace. . …… [1] (iii) Zinc has a melting point of 420 °C and a boiling point of 907 °C. The temperature inside the furnace is 1200 °C. Explain how this information shows that the zinc produced inside the furnace is a gas. . …… [1] (iv) The gaseous zinc is converted to molten zinc. Name this change of state. . …… [1] (c) Zinc reacts with dilute sulfuric acid to produce aqueous zinc sulfate. Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) Hydrated zinc sulfate crystals are made from aqueous zinc sulfate. Step 1 Solid zinc is added to dilute sulfuric acid until zinc is in excess. Step 2 Excess zinc is separated from aqueous zinc sulfate by filtration. Step 3 Aqueous zinc sulfate is heated until the solution is saturated. Step 4 The saturated solution is allowed to cool and crystallise. Step 5 The crystals are removed and dried. (i) Name the residue in step 2. . …… [1] (ii) In step 3, a saturated solution is produced. Describe what a saturated solution is. . …… . …… . …… [2] (iii) Name two compounds each of which react with dilute sulfuric acid to produce aqueous zinc sulfate. 1 . …… 2 . …… [2] (d) When hydrated magnesium sulfate crystals, MgSO4•xH2O, are heated they give off water. MgSO4•xH2O(s) → MgSO4(s) + xH2O(g) A student carries out an experiment to determine the value of x in MgSO4•xH2O. Step 1 Hydrated magnesium sulfate crystals were weighed. Step 2 Hydrated magnesium sulfate crystals were heated. Step 3 The remaining solid was weighed. (i) Describe how the student can ensure that all the water is given off. . …… . …… . …… [2] (ii) In an experiment, all the water was removed from 1.23 g of MgSO4•xH2O. The mass of MgSO4 remaining was 0.60 g. Mr: MgSO4 = 120; Mr: H2O = 18 Determine the value of x using the following steps. ● Calculate the number of moles of MgSO4 remaining. moles of MgSO4 = …… ● Calculate the mass of H2O given off. mass of H2O = …… g ● Calculate the moles of H2O given off. moles of H2O = …… ● Determine the value of x. x = …… [4] [Total: 17]

Question

Group I elements, Group VII elements and transition elements are found in different parts of the Periodic Table. (a) Describe the trend in the reactivity of Group I elements. . …… . …… [1] (b) When potassium is added to water a chemical reaction occurs. (i) State two observations that can be made when potassium is added to water. . …… . …… [2] (ii) Write a chemical equation for the reaction of potassium with water. . …… [2] (c) Excess aqueous potassium iodide is added to chlorine. (i) Write a chemical equation for the reaction that occurs when aqueous potassium iodide is added to chlorine. . …… [2] (ii) State the final colour of the reaction mixture. . …… [1] (d) Sodium is extracted from sodium chloride by electrolysis. (i) State the meaning of the term electrolysis. . …… . …… [2] (ii) State what must be done to sodium chloride before it can be electrolysed to produce sodium. . …… [1] (iii) Write an ionic half-equation for the change that occurs at the cathode during this electrolysis. . …… [1] (e) Chromium is a transition element. ● Chromium has a high melting point. ● Chromium is a good conductor of electricity. ● Many chromium compounds are soluble in water. ● ydrated chromium(III) sulfate is green. H ● Chromium forms the chlorides CrCl 2 and CrCl 3. ● Oxides of chromium act as catalysts in the manufacture of poly(ethene). (i) Use this information to give two properties of chromium which are different from properties of Group I elements such as sodium. 1 . …… 2 . …… [2] (ii) Use this information to give two properties of chromium which are similar to properties of Group I elements such as sodium. 1 . …… 2 . …… [2] [Total: 16]

Question

(a) A carboxylic acid and an ester are structural isomers. (i) State the meaning of the term structural isomers. . …… . …… . …… [2] (ii) Draw the structures of the carboxylic acid and the ester which both contain two carbon atoms. Show all of the atoms and all of the bonds. Name the carboxylic acid and the ester. carboxylic acid ester name …… name …… [4] (b) Part of a polyester chain is shown. This polyester is made from one monomer. O O O O O C O C O C O C (i) On the diagram draw a ring around one unit of the polymer that is repeated. [1] (ii) Name the type of polymerisation that produces polyesters. . …… [1] (iii) Complete the diagram to show the structure of the monomer used to produce this polyester. Show all of the atoms and all of the bonds in the functional groups. [2] (c) A polyamide is made from the two monomers shown. H 2N NH2 HOOC COOH Complete the diagram to show a section of the polyamide made from the two monomers. Show all of the atoms and all of the bonds in the linkages. [2] (d) Naturally occurring polyamides are constituents of food. (i) State the name given to naturally occurring polyamides. . …… [1] (ii) Name the monomers which form naturally occurring polyamides. . …… [1] [Total: 14] 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 16 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.).