Chemistry 0620/43 October/November 2022: question paper and mark scheme

Question

Atoms and ions are made from small particles called electrons, neutrons and protons. (a) Complete the table. particle relative charge relative mass 1 electron –1 1840 neutron proton [2] (b) Information about atoms and ions, A, B and C, is shown in the table. Complete the table. atom number of number of number of symbol or ion electrons neutrons protons A 18 20 20Ca 42 2+ B 18 17Cl 35 C 18 16 16 [6] [Total: 8]

Question

The table shows the melting points, boiling points and electrical conductivities of six substances, D, E, F, G, H and I. melting point boiling point conducts electricity conducts electricity substance / °C / °C when solid when liquid D 1083 2567 yes yes E –117 79 no no F 3550 4827 no no G 119 445 no no H –210 –196 no no I 801 1413 no yes (a) Identify the substance, D, E, F, G, H or I, which is: (b) Identify the substance, D, E, F, G, H or I, which is a metal. Give a reason for your choice. substance …… reason . …… [2] (c) Identify the substance, D, E, F, G, H or I, which has a macromolecular structure. Give two reasons for your choice. substance …… reason 1 . …… reason 2 . …… [3] (d) Identify the substance, D, E, F, G, H or I, which is an ionic solid. Give a reason for your choice. substance …… reason . …… . …… [2] [Total: 10]

Question

Aluminium is extracted from its ore by electrolysis. (a) Name the ore of aluminium which consists mainly of aluminium oxide. . …… [1] (b) State what is meant by the term electrolysis. . …… . …… [2] (c) Electrolysis is carried out on aluminium oxide dissolved in molten cryolite. waste gases positive electrode negative electrode aluminium oxide dissolved in molten cryolite aluminium (i) Give two reasons why the electrolysis is carried out on aluminium oxide dissolved in molten cryolite instead of electrolysing molten aluminium oxide only. 1 . …… 2 . …… [2] (ii) Write the ionic half-equation for the reaction occurring at the negative electrode. . …… [2] (iii) The positive electrodes are made of carbon. Explain why the positive carbon electrodes are replaced regularly. . …… . …… [2] (d) Aluminium is more reactive than copper. When aluminium is added to aqueous copper(II) sulfate, no immediate reaction is seen. Explain why. . …… [1] (e) Aluminium reacts with oxygen to form an amphoteric oxide. (i) State what is meant by the term amphoteric. . …… . …… [1] (ii) The reaction between aluminium oxide and aqueous sodium hydroxide forms a salt containing the negative ion Al O2–. The only other product is water. Write a chemical equation for the reaction between aluminium oxide and aqueous sodium hydroxide. . …… [2] (f) Gallium is in the same group as aluminium and forms similar compounds. Predict the formulae of: gallium(III) chloride …… gallium(III) sulfate. …… [2] [Total: 15]

Question

This question is about compounds of phosphorus. (a) Gaseous phosphorus(V) chloride decomposes into gaseous phosphorus(III) chloride and gaseous chlorine. When the three gases are present in a closed container the system reaches equilibrium. PCl 5(g) PCl 3(g) + Cl 2(g) (i) Complete the table using only the words increases, decreases or no change. effect on the rate of effect on the equilibrium the forward reaction yield (PCl 3(g) and Cl 2(g)) increasing the temperature increases decreasing the pressure adding a catalyst no change [4] (ii) The table shows that when the temperature increases, the equilibrium yields of PCl 3(g) and Cl 2(g) increase. State what conclusion can be made from this. . …… [1] (b) Complete the dot-and-cross diagram to show the electron arrangement in a molecule of phosphorus(III) chloride, PCl 3. Show outer shell electrons only. Cl P Cl Cl [2] (c) Phosphorus oxychloride has the formula POCl 3. Phosphorus oxychloride is the only product of the reaction between phosphorus(V) chloride, PCl 5, and phosphorus(V) oxide, P4O10. Write a chemical equation for the reaction between phosphorus(V) chloride and phosphorus(V) oxide. . …… [2] (d) Compound X has the following composition by mass. H, 3.66%; P, 37.80%; O, 58.54% Calculate the empirical formula of compound X. empirical formula = …… [2] (e) Compound Y has the empirical formula H3PO4 and a relative molecular mass of 98. Deduce the molecular formula of compound Y. molecular formula = …… [1] [Total: 12]

Question

This question is about sulfuric acid, H2SO4, and salts that can be made from sulfuric acid. (a) Sulfuric acid is manufactured by the Contact process. stage 1 Molten sulfur burns in air to produce sulfur dioxide. stage 2 Sulfur dioxide reacts with oxygen to form sulfur trioxide, SO3. stage 3 Sulfur trioxide reacts with concentrated sulfuric acid to form oleum, H2S2O7. stage 4 Oleum is converted into sulfuric acid. (i) The equation for the reaction in stage 2 is shown. 2SO2 + O2 2SO3 State the temperature and pressure used in stage 2. Name the catalyst used in stage 2. pressure . …… atm catalyst …… [3] (ii) Write the chemical equation for the reaction in stage 3. . …… [1] (iii) Name the substance that reacts with oleum in stage 4. . …… [1] (b) Name the black solid that is produced when concentrated sulfuric acid is added to sugar, C12H22O11. . …… [1] (c) Dilute sulfuric acid and aqueous potassium hydroxide are used to make aqueous potassium sulfate. H2SO4 + 2KOH → K2SO4 + 2H2O The method includes use of the following apparatus. dilute sulfuric acid conical flask 25.0 cm3 of aqueous potassium hydroxide (i) Calculate the volume of 0.0625 mol / dm3 dilute sulfuric acid, H2SO4, that completely reacts with 25.0 cm3 of 0.100 mol / dm3 potassium hydroxide, KOH, to produce aqueous potassium sulfate. Use the following steps. ● Calculate the number of moles of KOH in 25.0 cm3 of 0.100 mol / dm3 KOH. = …… mol ● Deduce the number of moles of H2SO4 that react with KOH. = …… mol ● Calculate the volume of H2SO4 required. volume = …… cm3 [3] (ii) The experiment is repeated using the same volume and concentration of potassium hydroxide and the same concentration of dilute sulfuric acid. In this second experiment, the product is aqueous potassium hydrogensulfate, KHSO4. H2SO4 + KOH → KHSO4 + H2O Use your answer to (c)(i) and the equation to deduce the volume of H2SO4 required. volume = …… cm3 [1] (d) Aqueous potassium hydrogensulfate, KHSO4(aq), contains the ions K+(aq), H+(aq) and SO42–(aq). Describe the observations in the following tests. (i) A flame test is carried out on aqueous potassium hydrogensulfate. . …… [1] (ii) Solid copper(II) carbonate is added to aqueous potassium hydrogensulfate. . …… . …… [2] (iii) An acidic solution containing aqueous barium ions, Ba2+(aq), is added to aqueous potassium hydrogensulfate. . …… [1] (e) Write the ionic equation for the reaction in (d)(iii). Include state symbols. . …… [3] [Total: 17]

Question

(a) Chloroethene (CH2=CHCl ) can be manufactured from 1,2-dichloroethane (CH2Cl CH2Cl ). The equation can be represented as shown. Cl H Cl H H C C Cl C C + H Cl H H H H (i) Some bond energies are given. bond energy bond in kJ / mol C–C 350 C=C 610 C–Cl 340 C–H 410 H–Cl 430 Use the bond energies in the table to calculate the energy change, in kJ / mol, of the reaction. Use the following steps. ● Calculate the energy needed to break bonds. energy = …… kJ ● Calculate the energy released when bonds form. energy = …… kJ ● Calculate the energy change of the reaction. energy change of the reaction = …… kJ / mol [3] (ii) Deduce whether the energy change for this reaction is exothermic or endothermic. Give a reason for your answer. . …… . …… [1] (b) Part of a synthetic polymer is shown. C 2H 5 H C 2H 5 H C C C C H H H H (i) State the number of monomer units that are needed to make the part of the polymer shown. . …… [1] (ii) Name and draw the structure of the monomer used to make this polymer. Show all of the atoms and all of the bonds. name …… structure [3] (iii) State the empirical formula of the polymer. . …… [1] (c) Proteins are natural polymers. Proteins are broken down into amino acids. The process is similar to how complex carbohydrates are broken down to give simple sugars. (i) Name the type of reaction in which proteins are broken down into amino acids. . …… [1] (ii) Name two types of substance that are used to break down proteins into amino acids. 1 . …… 2 . …… [2] (iii) Amino acids are colourless. A sample containing a mixture of amino acids is separated. Each amino acid is detected and identified. ● Name the process used to separate the amino acids. . …… ● Name the type of substance used to detect the amino acids. . …… ● Give the symbol of the value used to determine the identity of each amino acid after separation and detection. . …… [3] (d) Proteins are natural polymers. Proteins contain amide linkages. Synthetic polyamides also contain amide linkages. (i) Name a synthetic polyamide. . …… [1] (ii) Identify the two functional groups present in the monomers used to produce synthetic polyamides. 1 . …… 2 . …… [2] [Total: 18] 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.).