Chemistry 0620/32 February/March 2019: question paper and mark scheme

Question

This question is about electronic structures. (a) The electronic structures of five atoms, A, B, C, D and E, are shown. A B C D E Answer the following questions about these electronic structures. Each electronic structure may be used once, more than once or not at all. State which electronic structure, A, B, C, D or E, represents an atom: (i) of an element in Group III of the Periodic Table …… [1] (ii) of a monatomic gas …… [1] (iii) of carbon . …… [1] (iv) which has 18 protons . …… [1] (v) which forms a stable ion with a single negative charge. . …… [1] (b) Draw the electronic structure of a silicon atom. [2] [Total: 7]

Question

This question is about uranium and its compounds. (a) (i) An isotope of uranium is represented by the symbol shown. 92U 235 Deduce the number of electrons and neutrons in one atom of this isotope of uranium. number of electrons . …… number of neutrons …… [2] (ii) State the main use of this isotope of uranium. . …… [1] (b) Complete the sentence about isotopes using words from the list. atoms compound electrons element ions mixture molecules neutrons substance Isotopes are …… of the same …… which have the same proton number but a different number of …… . [3] (c) Uranium is a metal. Give two physical properties which are characteristic of all metals. 1 . …… 2 . …… [2] (d) Uranium reacts with hydrogen to form uranium hydride, UH3. The reaction is reversible. Complete the chemical equation for this reaction by: ●● balancing the equation ●● drawing the symbol for a reversible reaction in the box. 2U + …… H2 …. UH3 [3] (e) A compound of uranium has the formula UO2F2. Complete the table to calculate the relative formula mass of UO2F2. Use your Periodic Table to help you. number of atoms relative atomic mass uranium 1 238 1 × 238 = 238 oxygen fluorine relative formula mass = …… [2] [Total: 13]

Question

This question is about sulfur, sulfur compounds and the water from a sulfur spring. A sulfur spring is a natural source of water containing sulfur. (a) The table shows the mass of ions present in a 1000 cm3 sample of water from a sulfur spring. mass present in the ion present formula of ion 1000 cm3 sample / mg Br – 4 calcium Ca2+ 44 chloride Cl – 14 fluoride F– 6 iron(III) Fe3+ 2 magnesium Mg2+ 10 K+ 8 sodium Na+ 88 sulfate SO42– 92 Answer these questions using only information from the table. (i) Which negative ion is present in the lowest concentration? . …… [1] (ii) Give the name of the compound formed from only K+ and Br – ions. . …… [1] (iii) Calculate the mass of calcium ions present in a 250 cm3 sample of this water. mass of calcium ions = …… mg [1] (iv) Complete the equation to show the formation of a fluoride ion from a fluorine atom. F + …… F– [1] (b) Describe a test for sulfate ions. test . …… observations …… [2] (c) Solid sulfur is found around the edge of sulfur springs. (i) When heated, sulfur undergoes sublimation. What is meant by the term sublimation? . …… . …… [1] (ii) Sulfur reacts with hot concentrated sulfuric acid. Complete the chemical equation for this reaction. S + …… H2SO4 2H2O + …… SO2 [2] (iii) The table shows the solubility of sulfur and zinc in an organic solvent and in water. The organic solvent boils at 46 °C. solubility in element solubility in water organic solvent sulfur soluble insoluble zinc insoluble insoluble Use the information in the table to suggest how to obtain pure, dry samples of both sulfur and zinc from a mixture of sulfur powder and zinc powder. . …… . …… . …… . …… . …… . …… [4] (d) The structure of a sulfur compound is shown. F F O F S F F F Deduce the molecular formula of this compound showing the number of sulfur, fluorine and oxygen atoms. . …… [1] [Total: 14]

Question

A student investigated the reaction between zinc and dilute hydrochloric acid by measuring the volume of hydrogen gas produced at one minute intervals. Zn + 2HCl ZnCl 2 + H2 (a) Give the name of the salt formed in this reaction. . …… [1] (b) The graph shows the results using small pieces of zinc and dilute hydrochloric acid. 100 80 60 volume of hydrogen gas / cm3 40 20 0 0 1 2 3 4 5 time / minutes (i) Deduce the volume of hydrogen gas produced in the first two minutes of the reaction. …… cm3 [1] (ii) Draw a letter S on the graph to show where the reaction is slowing down but has not stopped completely. [1] (iii) Draw a line on the grid to show how the volume of hydrogen gas changes with time when the reaction is repeated with a catalyst. All other conditions are kept the same. [2] (iv) What effect do the following have on the rate of this reaction? ● Decreasing the temperature at which the reaction is done. All other conditions are kept the same. . …… ● Using zinc powder instead of small pieces of zinc. All other conditions are kept the same. . …… [2] (c) Describe a test for hydrogen. test . …… result . …… [2] (d) The table gives some information about the rate of reaction of zinc and some other metals with cold water and with steam. rate of reaction metal with cold water with steam iron no reaction hot iron reacts very slowly magnesium reacts very slowly hot magnesium reacts rapidly mercury no reaction no reaction strontium reacts rapidly reacts rapidly zinc no reaction hot zinc reacts slowly Put the five metals in order of their reactivity. Put the most reactive metal at the top. most reactive least reactive [2] (e) When 13.0 g of zinc reacts completely with sulfur, 19.4 g of zinc sulfide is formed. Calculate the maximum mass of zinc sulfide formed when 3.25 g of zinc reacts completely with sulfur. mass of zinc sulfide formed = …… g [1] [Total: 12]

Question

Aqueous sodium hydroxide is a base. (a) Describe the reaction of aqueous sodium hydroxide with: ●● a named acid . …… . …… . …… ●● ammonium salts . …… . …… . …… ●● a named indicator. . …… . …… . …… [5] (b) Ammonia is a soluble base. Which one of the following pH values could be the pH of aqueous ammonia? Draw a circle around the correct answer. pH 1 pH 5 pH 7 pH 10 [1] (c) Ammonia is used in the manufacture of some fertilisers. Which two of these compounds are present in fertilisers? Tick two boxes. copper(II) oxide potassium chloride sodium phosphate strontium fluoride sulfur dioxide [2] (d) Bacteria in the soil are able to convert ammonium compounds into oxides of nitrogen. The oxides of nitrogen can escape into the atmosphere. (i) State one other source of oxides of nitrogen in the atmosphere. . …… [1] (ii) State one effect of oxides of nitrogen on health. . …… [1] (iii) Oxides of nitrogen are greenhouse gases which contribute to climate change. Give the name of one other greenhouse gas which makes a major contribution to climate change. . …… [1] [Total: 11]

Question

This question is about chromium and chromium compounds. (a) (i) Suggest why chromium is manufactured by electrolysis and not by the reduction of chromium(VI) oxide, CrO3, with carbon. . …… [1] (ii) Suggest the products of electrolysis of molten chromium(VI) oxide at: ● the positive electrode . …… ● the negative electrode. …… [2] (b) Chromium can also be manufactured by the reduction of chromium(III) oxide, Cr2O3, with aluminium. Cr2O3 + 2Al Al 2O3 + 2Cr (i) How does this equation show that chromium(III) oxide is reduced? . …… . …… [1] (ii) The energy level diagram for this reaction is shown. Cr2O3 + 2Al energy Al 2O3 + 2Cr progress of reaction Explain how this diagram shows that the reaction is exothermic. . …… . …… [1] (c) Chromium is a transition element. Sodium is an element in Group I of the Periodic Table. Describe two ways in which the properties of chromium are different from those of sodium. 1 . …… 2 . …… [2] (d) Chromium is a silver-coloured metal. The diagram shows how a copper spoon can be electroplated with chromium. power supply (i) On the diagram, label: ● the cathode ● the electrolyte. [2] (ii) Give one observation that is made during the electroplating process. . …… [1] (iii) Suggest one reason why metal objects are electroplated. . …… [1] (e) Nichrome is an alloy of nickel, iron and chromium. Which one of these diagrams, J, K, L or M, best represents nichrome? J K L M . …… [1] [Total: 12]

Question

This question is about alkanes and petroleum fractions. (a) The table gives some information about alkanes. number of carbon melting point boiling point alkane atoms in each molecule in °C in °C methane 1 –182 –164 ethane 2 –183 –88 propane 3 –190 –42 butane 4 –135 0 Answer these questions using only information from the table. (i) Describe how the boiling points of the alkanes vary with the number of carbon atoms in each molecule. . …… . …… [1] (ii) Which alkane has the lowest melting point? . …… [1] (iii) Deduce the physical state of butane at –50 °C. Explain your answer. . …… . …… [1] (b) (i) Complete the dot-and-cross diagram to show the electron arrangement in a molecule of methane. Show outer shell electrons only. H H C H H [1] (ii) Complete the word equation for the complete combustion of methane. methane + oxygen + [2] (c) Complete the sentences about homologous series using words from the list. acidic alkenes alcohol carbohydrates chemical functional hydrocarbons physical Methane and ethane are …… which belong to the same homologous series. Members of the alkane homologous series have similar …… properties due to the presence of the same …… group. [3] (d) Petroleum is separated into useful fractions by fractional distillation. Match the fractions on the left with the uses on the right. The first one has been done for you. fraction use refinery gas fuel for aircraft bitumen bottled gas for heating kerosene fraction making chemicals naphtha fraction making roads [2] [Total: 11] 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.).