Chemistry 0620/33 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 Al Cl Ar K Ca Br I Pt Answer the following questions using only the symbol 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 fuel which is a gas at room temperature . …… [1] (ii) is used to kill bacteria in water . …… [1] (iii) forms a stable ion of type X3+ . …… [1] (iv) is a grey‑black non-metallic solid at room temperature . …… [1] (v) forms an ion which, on addition of aqueous sodium hydroxide, gives a white precipitate which is soluble in excess aqueous sodium hydroxide. . …… [1] (b) Sulfur has several isotopes. (i) Identify one correct statement about isotopes. Tick one box. They are molecules with the same number of neutrons but different numbers of protons. They are atoms with the same number of protons but different numbers of neutrons. They are molecules with the same number of protons but different numbers of electrons. They are atoms with the same number of neutrons but different numbers of protons. [1] (ii) An isotope of sulfur is shown. 16S 33 Deduce the number of protons and neutrons in this isotope. number of protons …… number of neutrons …… [2] (c) Complete the electronic structure of a sulfur atom. S [1] [Total: 9]

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 August 106.0 3.0 2.1 29.5 18.5 September 147.5 5.5 2.4 21.1 35.5 October 179.3 3.5 2.0 20.3 22.5 November 214.0 3.6 2.6 12.8 29.4 (a) Answer these questions using only the information in the table. (i) Name the pollutant that shows a decrease in concentration between August and November. . …… [1] (ii) Calculate the mass of oxides of nitrogen in 250 cm3 of the sample of air taken in August. …… nanograms [1] (b) Carbon monoxide is produced by the incomplete combustion of fossil fuels. (i) State the meaning of the term incomplete combustion. . …… . …… [1] (ii) Give one adverse effect of carbon monoxide on health. . …… [1] (c) Carbon monoxide is also produced when methane reacts with steam in the presence of a catalyst. (i) Explain why a catalyst is used in this reaction. . …… [1] (ii) Methane is an air pollutant. State one source of methane in the air. . …… [1] (d) (i) Complete the chemical equation for the reaction of carbon monoxide with oxygen. ……CO + O2 → ……CO2[2] (ii) Complete the energy level diagram for the reaction of carbon monoxide with oxygen by writing these words on the diagram: ●● reactants ●● products. energy progress of reaction [1] (iii) Explain, using information on the energy level diagram, how you know that this reaction is exothermic. . …… [1] (e) (i) Describe a test for carbon dioxide. test . …… result . …… [2] (ii) Identify which one of these pH values represents the pH of a solution of carbon dioxide in water. Draw a circle around the correct answer. pH 6 pH 7 pH 8 pH 14[1] [Total: 13]

Question

Some properties of four substances, A, B, C and D, are shown in the table. electrical electrical melting solubility substance conductivity conductivity point in water when solid when molten A does not conduct does not conduct low insoluble B conducts conducts high insoluble C does not conduct does not conduct very high soluble D does not conduct conducts high soluble Answer these questions using only the information in the table. (a) State which substance, A, B, C or D, is sulfur. Explain your answer. substance …… explanation …… . …… [3] (b) State which substance, A, B, C or D, is sodium chloride. Explain your answer. substance …… explanation …… . …… [3] [Total: 6]

Question

The structure of crotonic acid is shown. H H C H C H O C C H H O (a) (i) On the structure, draw a circle around the functional group which shows that this is an unsaturated compound. [1] (ii) Deduce the formula of crotonic acid to show the number of carbon, hydrogen and oxygen atoms. . …… [1] (iii) Complete the table to calculate the relative molecular mass of crotonic acid. Use your Periodic Table to help you. number relative type of atom of atoms atomic mass carbon 4 12 4 × 12 = 48 hydrogen 1 oxygen 16 relative molecular mass = …… [2] (b) Acids react with bases such as calcium oxide. Complete the word equation for the reaction of nitric acid with calcium oxide. nitric calcium …… …… + + acid oxide [2] (c) Calcium oxide is manufactured from limestone by thermal decomposition. (i) Give the name of the main chemical compound in limestone. . …… [1] (ii) State the meaning of the term thermal decomposition. . …… . …… [2] (d) Calcium oxide reacts with water to produce slaked lime. State one use of slaked lime. . …… . …… [1] [Total: 10]

Question

The formula of ethanol is C2H6O. (a) Draw the structure of ethanol to show all of the atoms and all of the bonds. [2] (b) Ethanol is a liquid at room temperature. Describe the motion and separation of the particles in ethanol. motion …… separation . …… [2] (c) Name the two products formed when ethanol undergoes complete combustion. 1 . …… 2 . …… [2] (d) Ethanol can be manufactured by the fermentation of glucose. One condition is using enzymes in yeast. (i) State two other conditions for fermentation. 1 . …… 2 . …… [2] (ii) Name the method used to separate the ethanol from the reaction mixture after fermentation is complete. . …… [2] (e) Alcohols can also be manufactured from alkenes. Complete the word equation for the manufacture of ethanol by this method. + ethanol [2] [Total: 12]

Question

The electrolysis of concentrated hydrochloric acid produces gases at each electrode. (a) Describe the electrolysis of concentrated hydrochloric acid. In your answer include: ●● a labelled diagram of the apparatus used for the electrolysis and collection of gases ●● the names of the products formed at the positive and the negative electrode. positive electrode . …… negative electrode …… [5] (b) Carbon dioxide is produced when hydrochloric acid reacts with sodium carbonate. Complete the chemical equation for this reaction. Na2CO3 + 2HCl → ……NaCl + …… + CO2[2] (c) Carbon dioxide reacts with carbon to produce carbon monoxide. CO2 + C → 2CO Explain how this equation shows that carbon dioxide has been reduced. . …… [1] [Total: 8]

Question

A student investigated the rate of reaction of excess calcium carbonate with dilute hydrochloric acid in a conical flask by two different methods. Method 1: M easure the volume of carbon dioxide produced at 10 second intervals. Method 2: M easure the loss in mass of the reaction mixture by weighing at 10 second intervals. (a) (i) Suggest one advantage of Method 1 compared with Method 2. . …… . …… [1] (ii) Explain why there is a decrease in mass of the reaction mixture in Method 2. . …… . …… [1] (b) The graph shows how the volume of carbon dioxide changes as the reaction proceeds, using Method 1. 60 50 40 volume of carbon dioxide 30 / cm3 20 10 0 0 20 40 60 80 100 120 140 time / s The student used large pieces of calcium carbonate. Answer these questions using information from the graph. (i) Describe how the rate of this reaction changes with time. . …… [1] (ii) Deduce the time taken to collect 36 cm3 of carbon dioxide. time = …… s [1] (iii) The experiment is repeated using smaller pieces of calcium carbonate. Draw a line on the grid to show how the volume of carbon dioxide changes with time when smaller pieces of calcium carbonate are used. All other conditions stay the same. [2] (iv) Describe what effect the following changes have on the rate of this reaction. ●● The temperature is increased. All other conditions stay the same. . …… ●● The concentration of the hydrochloric acid is decreased. All other conditions stay the same. . …… [2] [Total: 8]

Question

This question is about metals and compounds of metals. (a) (i) Sodium is a metal in Group I of the Periodic Table. Identify two correct statements about sodium. Tick two boxes. It is a relatively soft metal. It has a high melting point. It forms coloured chlorides. It has a lower density than most metals. It is a good insulator. [2] (ii) Some changes of state of sodium are shown. melting S solid liquid sodium sodium sodium gas R condensing Give the names of the changes of state represented by R and S. R …… S …… [2] (b) The table compares the reactions of four metals with dilute and with concentrated hydrochloric acid. observation with observation with metal dilute hydrochloric acid concentrated hydrochloric acid beryllium bubbles form rapidly bubbles form very rapidly copper no bubbles seen no bubbles seen iron bubbles form very slowly bubbles form slowly nickel no bubbles seen bubbles form slowly Put the four metals in order of their reactivity. Put the least reactive metal first. least reactive most reactive [2] (c) Crystals of magnesium chloride, MgCl 2•6H2O, can be prepared by adding excess magnesium powder to dilute hydrochloric acid. Describe how to prepare a sample of pure dry magnesium chloride crystals after the reaction is complete. In your answer describe how to: ●● remove the excess magnesium from the reaction mixture ●● crystallise the magnesium chloride ●● dry the crystals. . …… . …… . …… . …… . …… . …… . …… . …… [4] (d) When magnesium reacts with concentrated sulfuric acid, sulfur dioxide is produced. Complete this description of the test for sulfur dioxide using words from the list. blue chloride colourless green manganate(VII) sulfate(VI) The test for sulfur dioxide uses acidified aqueous potassium …… . The colour change is from purple to …… . [2] (e) Green nickel(II) sulfate crystals turn yellow when heated. NiSO4•7H2O NiSO4 + 7H2O green yellow nickel(II) sulfate nickel(II) sulfate (i) Suggest how you would change yellow nickel(II) sulfate to green nickel(II) sulfate. . …… [1] (ii) Identify which word best describes green nickel(II) sulfate with the formula NiSO4•7H2O. Draw a circle around the correct answer. anhydrous decomposed hydrated oxidised reduced[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 20 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.).