Chemistry 0620/31 October/November 2020: question paper and mark scheme

Question

(a) The diagram shows part of the Periodic Table. I II III IV V VI VII VIII H N O F Ne Mg Al Cl K Ca Cr Fe Cu Zn Br I Answer the following questions using only the symbols of the elements in the diagram. Each symbol may be used once, more than once or not at all. State the symbol of the element that: (i) is a monoatomic gas at room temperature . …… [1] (ii) is a liquid at room temperature . …… [1] (iii) forms a stable ion of type X2– . …… [1] (iv) is extracted from hematite . …… [1] (v) forms an ion whose aqueous solution gives a grey‑green precipitate on addition of aqueous ammonia. . …… [1] (b) Magnesium has several naturally occurring isotopes. (i) State the meaning of the term isotopes. . …… . …… [2] (ii) An isotope of magnesium is shown. 12Mg 26 Deduce the number of protons and neutrons in this isotope. number of protons …… number of neutrons …… [2] (c) Complete the electronic structure of a magnesium atom. Mg [1] [Total: 10]

Question

The table shows the mass of air pollutants, in nanograms, in 1000 cm3 samples of air taken over a four month period. mass of pollutant in 1000 cm3 of air / nanograms oxides of sulfur carbon month ozone particulates nitrogen dioxide monoxide April 108.2 0.6 1.3 24.6 17.8 May 121.6 1.8 1.6 23.2 19.2 June 126.7 1.6 1.9 22.8 20.0 July 163.9 4.5 2.2 20.1 22.0 (a) Answer these questions using only the information in the table. (i) Name the pollutant that shows a decrease in concentration between April and July. . …… [1] (ii) Name the pollutant present in the lowest concentration in May. . …… [1] (iii) Calculate the mass of sulfur dioxide in 250 cm3 of the sample of air taken in April. …… nanograms [1] (b) Oxides of nitrogen are produced when oxygen combines with nitrogen during thunderstorms. (i) State one other source of oxides of nitrogen in the air. . …… [1] (ii) Give one adverse effect of oxides of nitrogen on health. . …… [1] (iii) Complete the chemical equation for the reaction of nitrogen with oxygen to form nitrogen dioxide. …… + 2O2 → ……NO2[2] (c) Particulates are tiny solid particles in the air. The movement of these particles is shown by the arrows in the diagram. State the name given to this random motion of particles. . …… [1] [Total: 8]

Question

Some properties of four substances, A, B, C and D, are shown in the table. ductility conductivity substance strength (how easy it is hardness of heat to pull into a wire) A weak poor hard poor B strong not ductile very hard good C very strong very good hard good D weak poor soft good Answer these questions using only the information in the table. (a) State which substance, A, B, C or D, is best used in the core of an overhead electricity cable. Explain your answer. substance …… explanation …… . …… [3] (b) State which substance, A, B, C or D, is best used for the tip of a drill. Explain your answer. substance …… explanation …… . …… [3] [Total: 6]

Question

The structure of tartaric acid is shown. O O H C H O C H H C O H C O O H (a) (i) On the structure, draw a circle around one alcohol functional group. [1] (ii) Deduce the formula of tartaric acid to show the number of carbon, hydrogen and oxygen atoms. . …… [1] (iii) Complete the table to calculate the relative molecular mass of tartaric acid. Use your Periodic Table to help you. number relative type of atom of atoms atomic mass carbon 12 hydrogen 6 1 6×1=6 oxygen 16 relative molecular mass = …… [2] (b) Acids react with bases such as calcium hydroxide. (i) Complete the word equation for the reaction of nitric acid with calcium hydroxide. calcium …… …… nitric acid + + hydroxide [2] (ii) An aqueous solution of calcium hydroxide is alkaline. Identify which one of these pH values represents the pH of an alkaline solution. Draw a circle around the correct answer. pH 1 pH 4 pH 7 pH 10[1] (iii) One way of determining pH is to use a pH meter. Describe one other way of determining pH. . …… . …… [2] (iv) Farmers spread calcium hydroxide (slaked lime) on fields where crops are grown. Explain why. . …… . …… [1] (c) Calcium carbonate undergoes thermal decomposition. CaCO3 → CaO + CO2 (i) State the meaning of the term thermal decomposition. . …… . …… [2] (ii) Complete the energy level diagram for the thermal decomposition of calcium carbonate by writing these words on the diagram: ●● reactant ●● products. energy progress of reaction [1] (iii) Explain, using information on the energy level diagram, how you know that this reaction is endothermic. . …… [1] [Total: 14]

Question

Ethene is an alkene. (a) Draw the structure of ethene to show all of the atoms and all of the bonds. [1] (b) Ethene reacts with aqueous bromine. State the colour change observed when ethene reacts with aqueous bromine. from …… to …… [2] (c) Ethene reacts with steam. (i) Name and give the formula of the product of this reaction. name . …… formula . …… [2] (ii) Identify the type of chemical reaction that occurs when ethene reacts with steam. Draw a circle around the correct answer. addition fermentation polymerisation neutralisation[1] (d) Alkenes are produced by cracking hydrocarbons. Complete the chemical equation for the cracking of the hydrocarbon, C16H34, to produce an alkene and one other product. C16H34 → C6H12 + …… [1] (e) Poly(ethene) is produced by combining many ethene molecules. (i) Name the general term used to describe the small molecules which combine to form a polymer. . …… [1] (ii) Nylon is a polymer. State one use for nylon. . …… [1] (iii) Describe one pollution problem caused by non-biodegradable plastics. . …… [1] [Total: 10]

Question

Electrolysis is used to extract metals from metal compounds. (a) Describe the electrolysis of molten lead(II) bromide. In your answer include: ●● a labelled diagram of the apparatus used ●● the names of the products formed at the positive and the negative electrodes. positive electrode . …… negative electrode …… [5] (b) Use the kinetic particle model to describe the arrangement and motion of the particles in molten (liquid) lead. arrangement …… motion . …… [2] (c) Lead is a metal which is soft and has a relatively low melting point. State two other physical properties of metals such as lead. 1 . …… 2 . …… [2] (d) Lead is formed when red lead oxide, Pb3O4, is heated with carbon. Pb3O4 + 4C → 3Pb + 4CO Explain how this equation shows that Pb3O4 has been reduced. . …… [1] [Total: 10]

Question

Catalysts increase the rate of chemical reactions. (a) Name the type of metals often used as catalysts. . …… [1] (b) A student investigated the reaction of zinc powder with excess dilute hydrochloric acid in the absence of a catalyst. Zn + 2HCl → ZnCl 2 + H2 The student measured the volume of hydrogen gas produced at 10 second intervals. The graph shows the results. 120 100 80 volume of hydrogen 60 / cm3 40 20 0 0 10 20 30 40 50 60 70 time / s Answer these questions using information from the graph. (i) Deduce the volume of hydrogen produced in the first 25 seconds of the experiment. volume = …… cm3 [1] (ii) Explain why no more hydrogen is produced after 50 seconds. . …… [1] (iii) The experiment is repeated using a catalyst. Draw a line on the grid to show how the volume of hydrogen changes with time when a catalyst is used. All other conditions stay the same. [2] (iv) Describe what effect the following changes have on the rate of the reaction. ●● The concentration of hydrochloric acid is decreased. All other conditions stay the same. . …… ●● Large pieces of zinc are used. All other conditions stay the same. . …… [2] (c) (i) Describe a test for hydrogen. test . …… result . …… [2] (ii) State one use of hydrogen. . …… [1] [Total: 10]

Question

This question is about metals and compounds of metals. (a) Identify two correct statements about transition elements. Tick two boxes. All transition elements are metals which are brown in colour. Transition elements have high densities. Compounds of transition elements are white in colour. Transition elements have high melting points. Transition elements are found between Groups IV and V of the Periodic Table. [2] (b) The table compares the ease of reduction of some metal oxides with carbon. metal oxide ease of reduction with carbon cobalt(II) oxide reduced at 450 °C copper(II) oxide reduced below 450 °C magnesium oxide reduced above 1400 °C manganese(II) oxide reduced at 1400 °C Put the four metals in order of their reactivity. Put the least reactive metal first. least reactive most reactive [2] (c) Crystals of copper(II) sulfate, CuSO4•5H2O, can be prepared by heating excess copper(II) oxide powder with dilute sulfuric acid. (i) Describe how to prepare a sample of pure dry copper(II) sulfate crystals after the reaction is complete. In your answer describe how to: ●● remove the excess copper(II) oxide from the reaction mixture ●● crystallise the copper(II) sulfate ●● dry the crystals. . …… . …… . …… . …… . …… . …… . …… . …… [4] (ii) Identify the word that best describes copper(II) sulfate. Draw a circle around the correct answer. acid halogen polymer salt[1] (d) A few drops of water are added to a sample of solid anhydrous copper(II) sulfate, CuSO4. (i) The reaction is reversible. CuSO4 + 5H2O CuSO4•5H2O Draw in the box, the sign for a reversible reaction. [1] (ii) State the colour change observed when water is added to anhydrous copper(II) sulfate. from …… to …… [2] [Total: 12] 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 16 rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon 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.).