Chemistry 0620/41 May/June 2019: question paper and mark scheme

Question

This question is about the structures of atoms and ions. (a) Define the term proton number. . …… . …… [2] (b) (i) Complete the table to show the number of protons, neutrons and electrons present in 24 atoms of 12 Mg and 12 26 Mg. number of number of number of protons neutrons electrons 12Mg 24 12Mg 26 [2] 24 (ii) What term is used to describe atoms of the same element, such as 12 Mg and 12 26 Mg? . …… [1] 24 (iii) Explain why the chemical properties of 12 Mg and 12 26 Mg are the same. . …… . …… [2] (c) Complete the table to identify the atoms and ions which have the following numbers of protons, neutrons and electrons. number of number of number of protons neutrons electrons 11Na 23 + 11 12 10 4 5 4 17 20 18 [4] (d) State the electronic structure of the following atom and ion. Al …… S2– . …… [2] [Total: 13]

Question

Z is a covalent substance. In an experiment, a sample of pure solid Z was continually heated for 11 minutes. The graph shows how the temperature of the sample of pure Z changed during the first 9 minutes. 240 220 200 180 160 140 temperature / °C 120 100 80 60 40 20 0 0 1 2 3 4 5 6 7 8 9 10 11 12 time / minutes (a) What is the melting point of pure Z? …… °C [1] (b) The sample of pure Z began to boil at 9 minutes. It was boiled for 2 minutes. Use this information to sketch on the grid how the temperature of the sample of pure Z changed between 9 minutes and 11 minutes. [1] (c) The sample of pure Z was continually heated between 2 minutes and 5 minutes. Explain, in terms of attractive forces, why there was no increase in the temperature of the sample of pure Z between 2 minutes and 5 minutes. . …… . …… . …… [2] (d) Describe how the motion of particles of pure Z changed from 0 minutes to 2 minutes. . …… . …… [2] (e) The experiment was repeated using a solid sample of impure Z. Suggest the differences, if any, in the melting point and boiling point of the sample of impure Z compared to the sample of pure Z. melting point …… boiling point …… [2] (f) A sample of pure Z was allowed to cool from 120 °C to 20 °C. The total time taken was 8 minutes. Starting from point ×, sketch on the grid how the temperature of the sample of pure Z changed between 0 minutes and 8 minutes. 200 180 160 140 120 temperature / °C 100 80 60 40 20 0 0 1 2 3 4 5 6 7 8 9 10 11 12 time / minutes [2] [Total: 10]

Question

Zinc and copper are elements next to each other in the Periodic Table. (a) Zinc is obtained from zinc blende in a two-step process. ●● In step 1, zinc blende is converted into zinc oxide. ●● In step 2, zinc oxide is converted into zinc in a blast furnace. Outline how each of these steps are done. In your answer: ●● give one chemical equation for each step ●● describe how zinc is removed from the blast furnace in step 2. step 1 …… . …… chemical equation . …… step 2 …… . …… chemical equation . …… removal of zinc in step 2 …… . …… [5] (b) Name the alloy formed when zinc is mixed with copper. . …… [1] (c) Copper is a transition element. It can have variable oxidation states. State two other chemical properties of transition elements which make them different from Group I elements. 1 . …… 2 . …… [2] (d) A compound of copper can be used to test for water. (i) State the full name of this compound of copper. . …… [1] (ii) State the colour change that occurs when water is added to this compound of copper. from …… to …… [2] (e) Aqueous potassium iodide reacts with aqueous copper(II) sulfate to produce iodine. (i) Balance the chemical equation for this reaction. KI + CuSO4 CuI + I2 + K2SO4 [2] (ii) Deduce the charge on the copper ion in CuI. . …… [1] (iii) In terms of electron transfer, explain why copper is reduced in this reaction. . …… [1] (iv) Identify the reducing agent. . …… [1] [Total: 16]

Question

Ethanoic acid is a weak acid and hydrochloric acid is a strong acid. Both ethanoic acid and hydrochloric acid dissociate in aqueous solution. (a) (i) Define the term acid. . …… [1] (ii) The chemical equation shows the changes which occur when the strong acid, hydrochloric acid, is added to water. HCl (aq) H+(aq) + Cl –(aq) Complete the chemical equation to show the changes which occur when the weak acid, ethanoic acid, is added to water. CH3COOH(aq) …… [2] (b) A student does experiments to show that hydrochloric acid is a strong acid and ethanoic acid is a weak acid. The student adds an excess of hydrochloric acid and an excess of ethanoic acid to separate samples of lumps of calcium carbonate. Only the identity of the acid is changed between the experiments. All other conditions are kept the same. (i) State two observations which would show that hydrochloric acid is a stronger acid than ethanoic acid. 1 . …… 2 . …… [2] (ii) The student uses the same size container and checks that the pressure is the same for each experiment. State three other conditions which must be kept the same to ensure fair testing. 1 . …… 2 . …… 3 . …… [3] (c) Hydrochloric acid produces salts called chlorides. Magnesium carbonate reacts with hydrochloric acid to produce magnesium chloride. MgCO3 + 2HCl MgCl 2 + H2O + CO2 A student used 50.00 cm3 of 2.00 mol / dm3 hydrochloric acid in an experiment to produce magnesium chloride. Calculate the mass, in g, of magnesium carbonate needed to react exactly with 50.00 cm3 of 2.00 mol / dm3 hydrochloric acid using the following steps. ●● Calculate the number of moles of HCl present in 50.00 cm3 of 2.00 mol / dm3 HCl. …… mol ●● Determine the number of moles of MgCO3 which would react with 50.00 cm3 of 2.00 mol / dm3 HCl. …… mol ●● Calculate the relative formula mass, Mr, of MgCO3. Mr of MgCO3 = …… ●● Calculate the mass of MgCO3 needed to react exactly with 50.00 cm3 of 2.00 mol / dm3 HCl. mass = …… g [4] (d) A student prepares crystals of magnesium chloride by adding an excess of magnesium carbonate to 50.00 cm3 of 2.00 mol / dm3 hydrochloric acid. The student filters the mixture and rinses the residue. (i) Why does the student add an excess of magnesium carbonate? . …… [1] (ii) Why does the student rinse the residue? . …… [1] (iii) Describe how the student would obtain pure crystals of magnesium chloride from the filtrate. . …… . …… . …… [3] (e) Silver chloride, AgCl, is insoluble. It can be made by a precipitation reaction between aqueous barium chloride and a suitable aqueous silver salt. (i) What is meant by the term precipitate? . …… . …… [2] (ii) Name a suitable silver salt to use to prepare silver chloride. Complete the chemical equation to show the formation of insoluble silver chloride from aqueous barium chloride and the silver salt you have named. name of a suitable silver salt …… BaCl 2 + …… …… + …… [3] [Total: 22]

Question

The structures of five alkenes, A, B, C, D and E, are shown. A B C H H H CH3 H CH2CH3 C C C C C C H H H H H H D E H CH2CH2CH3 H CH2CH2CH2CH3 C C C C H H H H (a) What is the general formula of alkenes? . …… [1] (b) What is the molecular formula of alkene D? . …… [1] (c) Predict which alkene, A, B, C, D or E, has the highest boiling point. Explain your answer. alkene …… explanation …… . …… [2] (d) Which alkene, A, B, C, D or E, diffuses most quickly? Explain your answer. alkene …… explanation …… . …… [2] (e) A student added aqueous bromine to alkene C. C H CH2CH3 C C H H Describe the colour change seen and draw the structure of the product. Show all of the atoms and all of the bonds. colour change from …… to . …… structure [2] (f) Two different alcohols can be produced from alkene B by an addition reaction. B H CH3 C C H H (i) Draw the structures of the two alcohols. Show all of the atoms and all of the bonds. [2] (ii) State the reagent and conditions needed to produce an alcohol from alkene B. reagent …… conditions …… . …… [3] (g) Alkene C can be converted into a polymer. C H CH2CH3 C C H H (i) What type of polymerisation occurs? . …… [1] (ii) Suggest the name of the polymer formed. . …… [1] (iii) Complete the chemical equation to show this polymerisation. H CH2CH3 n C C H H [3] (iv) State the empirical formula of the polymer formed. . …… [1] [Total: 19] 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.).