Chemistry 0620/31 October/November 2024: question paper and mark scheme

Question

(a) Fig. 1.1 shows part of the Periodic Table. I II III IV V VI VII VIII H F Na Al P S Cl Ar K Ca Ni Br I Fig. 1.1 Answer the following questions using only the elements in Fig. 1.1. Each symbol of the element may be used once, more than once or not at all. Give the symbol of the element that: (i) produces a lilac colour in a flame test …… [1] (ii) has an atom with only two occupied electron shells …… [1] (iii) is an unreactive gas …… [1] (iv) forms an ion that gives a white precipitate after the addition of excess sodium hydroxide …… [1] (v) forms an ion with a charge of 2– …… [1] (vi) is added to iron to make stainless steel. …… [1] (b) Stainless steel is a mixture. State two characteristics of a mixture. 1 …… 2 …… [2] [Total: 8] Question 2 starts on the next page.

Question

Nitrogen molecules are diatomic. (a) (i) State the meaning of the term diatomic. …… [1] (ii) State the percentage of nitrogen in clean, dry air. …… [1] (b) Ammonia has a simple molecular structure. Complete Fig. 2.1 to show the dot-and-cross diagram for a molecule of ammonia. Show outer shell electrons only. H N H H Fig. 2.1 [2] (c) Sodium chloride has a giant ionic structure of positive and negative ions. (i) State the general name given to any positive ion. …… [1] (ii) State one physical property of an ionic compound. …… [1] (d) Graphite is used as an electrode. (i) State one other use of graphite. …… [1] (ii) Choose the correct statement that describes the structure and bonding in graphite. Tick (✓) one box. simple covalent molecule giant ionic simple ionic giant covalent [1] [Total: 8]

Question

(a) Polluted water can contain harmful substances such as plastics and phosphates. State two other types of harmful substance in polluted water. 1 …… 2 …… [2] (b) Table 3.1 shows the masses of ions, in mg, present in a 1000 cm3 sample of polluted water. Table 3.1 mass of ion in 1000 cm3 name of ion formula of ion of polluted water / mg ammonium NH4+ 0.6 bromide Br – 0.3 calcium Ca2+ 2.5 chloride Cl – 2.5 hydrogencarbonate HCO3– 12.0 magnesium Mg2+ 0.8 NO3– 0.4 phosphate PO43– 0.5 potassium K+ 5.3 silicate SiO32– 3.0 sodium Na+ 9.2 sulfate SO42– 0.5 Answer these questions using the information from Table 3.1. (i) Name the negative ion that has the lowest concentration. …… [1] (ii) State the name of the NO3– ion. …… [1] (iii) Calculate the mass of sodium ions in 250 cm3 of polluted water. mass = …… mg [1] (c) Fig. 3.1 shows some of the stages in the treatment of the domestic water supply. use of sedimentation → filtration → → carbon …… Fig. 3.1 (i) Complete Fig. 3.1 by adding the final stage. [1] (ii) State why carbon is added to drinking water. …… [1] (d) Describe how to test the purity of water using melting point. …… [2] (e) Complete the symbol equation for the reaction of phosphorus(V) chloride, PCl 5, with water. 2PCl 5 + 8H2O → ……H3PO4 + ……HCl [2] [Total: 11]

Question

(a) Fig. 4.1 shows the displayed formula of compound A. H H H H H C C C C C H H H H H Fig. 4.1 (i) Explain why compound A is described as unsaturated. …… [1] (ii) Explain why compound A is a hydrocarbon. …… [1] (iii) Deduce the molecular formula of compound A. …… [1] (b) Compound A reacts with steam to produce an alcohol. (i) State the general formula for the homologous series of alcohols. …… [1] (ii) Ethanol is an alcohol which can be manufactured by fermentation. ● Name two substances needed for fermentation. 1 …… 2 …… ● Give two conditions needed for fermentation. 1 …… 2 …… [4] (iii) State one use of ethanol. …… [1] (c) A compound in the same homologous series as compound A reacts with ozone, O3, to form compound B. (i) Define the term homologous series. …… [2] (ii) The molecular formula for compound B is C6H12O3. Complete Table 4.1 to calculate the relative molecular mass of C6H12O3. Table 4.1 relative type of atom number of atoms atomic mass carbon 6 12 6 × 12 = 72 hydrogen 1 oxygen 16 relative molecular mass = …… [2] [Total: 13]

Question

(a) Table 5.1 shows some properties of five halogens. Table 5.1 melting point boiling point atomic radius halogen / °C / °C / nm fluorine –220 –188 chlorine –101 –35 0.099 bromine –7 +59 0.114 iodine +184 0.133 astatine +302 +337 0.155 Use the information in Table 5.1 to predict: (i) the melting point of iodine …… [1] (ii) the atomic radius of fluorine …… [1] (iii) the physical state of bromine at 0 °C. Give a reason for your answer. physical state …… reason …… [2] (b) Aqueous chlorine reacts with aqueous potassium iodide. (i) Complete the word equation for this reaction. potassium …… …… chlorine + → + iodide [2] (ii) Explain why aqueous iodine does not react with aqueous potassium bromide. …… [1] (c) Fluorine reacts with hot concentrated sodium hydroxide to produce sodium fluoride, water and oxygen. (i) Complete the symbol equation for this reaction. 2F2 + 4NaOH → ……NaF + 2H2O + …… [2] (ii) Describe a test for oxygen. test …… observations …… [2] [Total: 11]

Question

This question is about metals. (a) Metals are good electrical conductors. State three other typical physical properties of metals. 1 …… 2 …… 3 …… [3] (b) (i) Complete Table 6.1 to show the number of electrons, neutrons and protons in the potassium atom and the nickel ion shown. Table 6.1 number of number of number of electrons neutrons protons 41 19K 19 62 2+ 28Ni 34 [3] (ii) Write the electronic configuration of the potassium atom. …… [1] (c) Choose one property from the list that shows that nickel is a transition element. Tick (✓) one box. has a low density forms coloured compounds has a low melting point does not act as a catalyst [1] (d) Nickel can be manufactured by reducing nickel(II) oxide with carbon monoxide and hydrogen. 2NiO + CO + H2 → 2Ni + H2O + CO2 Explain how this equation shows that nickel(II) oxide is reduced. …… [1] (e) Table 6.2 shows the observations when four different metals are heated with steam. Table 6.2 metal observations with steam chromium forms an oxide layer slowly copper forms an oxide layer very slowly magnesium forms an oxide layer rapidly niobium does not form an oxide layer Put the four metals in order of their reactivity. Put the least reactive metal first. least reactive most reactive [2] [Total: 11]

Question

This question is about acids, bases and salts. (a) Crystals of potassium chloride can be made by reacting an acid with an alkali. (i) Name the acid and the alkali used. acid …… alkali …… [2] (ii) Choose from the list the type of reaction that takes place when an acid reacts with an alkali. Draw a circle around your chosen answer. addition neutralisation redox substitution [1] (iii) Thymolphthalein is an acid–base indicator. State the colour of thymolphthalein at pH 2 and at pH 12. colour at pH 2 …… colour at pH 12 …… [2] (iv) Describe how to make dry crystals of potassium chloride from an aqueous solution of potassium chloride. …… [2] (b) Crystals of potassium chloride dissolve in water. This process is endothermic. (i) Define the term endothermic. …… [1] (ii) Fig. 7.1 shows the reaction pathway diagram for dissolving potassium chloride in water. KCl (aq) energy KCl (s) + H2O(l) progress of reaction Fig. 7.1 Answer the following questions using the information in Fig. 7.1. ● State the meaning of the state symbol (l). ● Explain how Fig. 7.1 shows that dissolving potassium chloride in water is endothermic. [2] [Total: 10]

Question

(a) A student investigates the reaction of small pieces of zinc with excess dilute sulfuric acid of three different concentrations. The time taken for each reaction to finish is recorded. The three concentrations of the acid are: ● 0.2 mol / dm3 ● 0.4 mol / dm3 ● 0.8 mol / dm3. All other conditions stay the same. Table 8.1 shows the time taken for each reaction to finish. Table 8.1 concentration of time taken for the dilute sulfuric acid reaction to finish in mol / dm3 in s 92 23 46 (i) Complete Table 8.1 by writing the concentrations in the first column. [1] (ii) Describe the effect on the time taken for the reaction to finish when the reaction is carried out in the presence of a catalyst. All other conditions stay the same. …… [1] (iii) Describe the effect on the time taken for the reaction to finish when larger pieces of zinc are used instead of small pieces of zinc. All other conditions stay the same. …… [1] (b) Dilute sulfuric acid is electrolysed using inert electrodes. (i) Name the products at the positive and negative electrodes. product at the positive electrode …… product at the negative electrode …… [2] (ii) Choose from the list the metal used as an inert electrode. Draw a circle around your chosen answer. calcium magnesium platinum sodium [1] (c) Zinc is a solid at room temperature. Describe the arrangement and separation of the particles in solid zinc. arrangement …… separation …… [2] [Total: 8] 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 89–103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 actinoids Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og francium radium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson – – – – – – – – – – – – – – – – – 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.).