Chemistry 0620/42 May/June 2019: question paper and mark scheme

Question

The names of eight substances are given. aluminium oxide calcium oxide ethanol nitrogen iron(III) oxide methane oxygen silicon(IV) oxide Answer the following questions about these substances. Each substance may be used once, more than once or not at all. State which substance is: (a) the main constituent of natural gas . …… [1] (b) a reactant in respiration . …… [1] (c) the main constituent of bauxite . …… [1] (d) a product of photosynthesis . …… [1] (e) a greenhouse gas . …… [1] (f) a macromolecular solid. . …… [1] [Total: 6] 11Na, 11Na and 11Na are isotopes of sodium. 22 23 24

Question

(a) (i) Describe how these sodium isotopes are the same and how they are different in terms of the total number of protons, neutrons and electrons in each. same . …… . …… different . …… . …… [3] (ii) Why do all three isotopes have an overall charge of zero? . …… . …… [1] (iii) Why do all three isotopes have the same chemical properties? . …… . …… [2] (iv) Why do sodium ions have a charge of +1? . …… . …… [1] (b) Carbon is an element which exists in different forms. (i) Name two forms of the element carbon that have giant covalent structures. …… and . …… [1] (ii) Name the oxide of carbon that is a toxic gas. . …… [1] [Total: 9]

Question

This question is about phosphorus and compounds of phosphorus. (a) Phosphorus has the formula P4. Some properties of P4 are shown. melting point / °C 45 boiling point / °C 280 electrical conductivity non-conductor solubility in water insoluble (i) Name the type of bonding that exists between the atoms in a P4 molecule. . …… [1] (ii) Explain, in terms of attractive forces between particles, why P4 has a low melting point. . …… . …… [1] (iii) Explain why phosphorus is a non-conductor of electricity. . …… . …… [1] Phosphorus, P4, reacts with air to produce phosphorus(V) oxide, P4O10. (b) (i) Write a chemical equation for this reaction. . …… [2] (ii) What type of chemical reaction is this? . …… [1] (c) Phosphorus(V) oxide, P4O10, is an acidic oxide. Phosphorus(V) oxide, P4O10, reacts with aqueous sodium hydroxide to form a salt containing the phosphate ion, PO43–. Water is the only other product. Write a chemical equation for the reaction between phosphorus(V) oxide and aqueous sodium hydroxide. . …… [2] (d) Phosphine has the formula PH3. Complete the dot-and-cross diagram to show the electron arrangement in a molecule of phosphine. Show outer shell electrons only. H H P H [2] (e) Phosphine, PH3, has a similar chemical structure to ammonia, NH3. Ammonia acts as a base when it reacts with sulfuric acid. (i) What is meant by the term base? . …… [1] (ii) Write a chemical equation for the reaction between ammonia and sulfuric acid. . …… [2] [Total: 13]

Question

Methanol is made industrially by reacting carbon monoxide with hydrogen. The gases react at a temperature of 250 °C and a pressure of 75 atmospheres. CO(g) + 2H2(g) CH3OH(g) The forward reaction is exothermic. (a) Suggest a source of hydrogen for this industrial process. . …… [1] (b) Complete the table using only the words increases, decreases or no change. effect on the rate effect on the equilibrium of the reverse reaction yield of CH3OH(g) adding a catalyst no change increasing the temperature increases decreasing the pressure [4] (c) Methanol is a member of the homologous series of alcohols. (i) State two general characteristics of a homologous series. 1 . …… 2 . …… [2] (ii) Draw the structures of two different alcohols, each containing three carbon atoms. Show all of the atoms and all of the bonds. Name these two alcohols. name …… name …… [4] (iii) What term is used to describe compounds with the same molecular formula but different structural formulae? . …… [1] (d) Alcohols react with carboxylic acids to produce esters. (i) The structure of ester X is shown. O H C H H O C C H H H Name ester X. . …… [1] (ii) Give the name of the carboxylic acid and the alcohol that react together to produce ester X. carboxylic acid …… alcohol …… [2] (iii) Ester Y is different from ester X but also has the formula C3H6O2. Draw the structure of ester Y. Show all of the atoms and all of the bonds. . …… [2] [Total: 17]

Question

Copper(II) sulfate crystals, CuSO4.5H2O, are hydrated. Copper(II) sulfate crystals are made by reacting copper(II) carbonate with dilute sulfuric acid. The equation for the overall process is shown. CuCO3 + H2SO4 + 4H2O CuSO4.5H2O + CO2 step 1 Powdered solid copper(II) carbonate is added to 50.0 cm3 of 0.05 mol / dm3 sulfuric acid until the copper(II) carbonate is in excess. step 2 The excess of copper(II) carbonate is separated from the aqueous copper(II) sulfate. step 3 The aqueous copper(II) sulfate is heated until the solution is saturated. step 4 The solution is allowed to cool and crystallise. step 5 The crystals are removed and dried. Calculate the maximum mass of the copper(II) sulfate crystals, CuSO4.5H2O, that can form (a) using the following steps. ●● Calculate the number of moles of H2SO4 in 50.0 cm3 of 0.05 mol / dm3 H2SO4. …… mol ●● Determine the number of moles of CuSO4.5H2O that can form. …… mol ●● The Mr of CuSO4.5H2O is 250. Calculate the maximum mass of CuSO4.5H2O that can form. …… g [3] (b) Steps 1–5 were done correctly but the mass of crystals obtained was less than the maximum mass. Explain why. . …… [1] (c) State two observations that would indicate that the copper(II) carbonate is in excess in step 1. 1 . …… 2 . …… [2] (d) When the reaction in step 1 is done using lumps of copper(II) carbonate instead of powder, the rate of reaction decreases. All other conditions are kept the same. Give a reason for this. Explain your answer in terms of particles. . …… . …… . …… [2] (e) Name a different substance, other than copper(II) carbonate, that could be added to dilute sulfuric acid to produce copper(II) sulfate in step 1. . …… [1] Name the process used to separate the aqueous copper(II) sulfate from the excess of (f) copper(II) carbonate in step 2. . …… [1] The solution of aqueous copper(II) sulfate was heated until it was saturated in step 3. (g) (i) Suggest what is meant by the term saturated solution. . …… . …… . …… [2] (ii) What evidence would show that the solution was saturated in step 3? . …… [1] (iii) Why should the aqueous copper(II) sulfate not be heated to dryness in step 3? . …… [1] [Total: 14]

Question

The halogens are the elements in Group VII of the Periodic Table. (a) Predict the physical state and colour of astatine at room temperature and pressure. physical state . …… colour . …… [2] (b) When chlorine reacts with aqueous potassium bromide a displacement reaction occurs. (i) Describe the colour change of the solution. from …… to …… [2] (ii) Write a chemical equation for this reaction. . …… [2] (c) Reactions occur when some aqueous solutions of halogens are added to aqueous solutions of halides. Use the key to complete the table to show the results of adding halogens to halides. key = reaction = no reaction halides KCl (aq) KBr(aq) KI(aq) Cl 2(aq) halogens Br2(aq) I2(aq) [2] [Total: 8]

Question

(a) Displacement reactions occur between metals and metal ions. Displacement reactions can be used to determine the order of reactivity of metals such as lead (Pb), nickel (Ni), and silver (Ag). The ionic equation for a displacement reaction is shown. Ni(s) + Pb2+(aq) Pb(s) + Ni2+(aq) The ionic half-equations for this reaction are shown. Ni(s) Ni2+(aq) + 2e– Pb2+(aq) + 2e– Pb(s) The ionic half-equations show that electrons are donated by nickel atoms and accepted by lead ions. (i) Identify the reducing agent in the displacement reaction. Give a reason for your answer. reducing agent. …… reason. …… [2] (ii) What is the general term given to the type of reaction in which electrons are transferred from one species to another? . …… [1] (b) The ionic equation for another displacement reaction is shown. Pb(s) + 2Ag+(aq) 2Ag(s) + Pb2+(aq) Write the two ionic half-equations for this reaction. 1 . …… 2 . …… [2] (c) Use the information in (a) and (b) to put the three metals lead, nickel and silver in order of reactivity. most reactive least reactive [1] (d) Nickel is a transition element. Nickel is stronger than sodium. Describe two other differences in the physical properties of nickel and sodium. 1 . …… 2 . …… [2] (e) Predict one difference in the appearance of aqueous solutions of nickel compounds compared to aqueous solutions of sodium compounds. . …… . …… [1] (f) Copper is refined (purified) by electrolysis. Nickel can be refined using a similar method. (i) The diagram shows the refining of nickel by electrolysis. Complete the labels in the boxes. power supply + – anode made of cathode made of electrolyte of [3] (ii) Indicate, by writing N on the diagram, where nickel is produced. [1] [Total: 13] 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.).