Chemistry 0620/32 February/March 2025: question paper and mark scheme

Question

A list of symbols and formulae is shown. Ba2+ C Cl 2 Cl – CO CO2 CuO H2 H 2O K+ Na+ O2– Answer the following questions using only these symbols and formulae. Each symbol or formula may be used once, more than once or not at all. (a) State which symbol or formula represents: (i) an element used as an inert electrode for electrolysis …… [1] (ii) an ion formed when an atom gains two electrons …… [1] (iii) a basic oxide …… [1] (iv) an ion that gives a yellow colour in a flame test …… [1] (v) a toxic gas formed during the incomplete combustion of methane …… [1] (vi) an element used as a reactant in a fuel cell. …… [1] (b) Water, H2O, is a simple covalent molecule. Complete Fig. 1.1 to show the dot‑and‑cross diagram for a molecule of water. Show outer shell electrons only. O H H Fig. 1.1 [2] [Total: 8]

Question

This question is about metals and alloys. (a) Table 2.1 shows information about the reactions of four different metals with oxygen. Table 2.1 metal reaction with oxygen calcium burns rapidly to form an oxide cobalt burns slowly to form an oxide platinum no reaction tin forms an oxide but does not burn Put the four metals in order of their reactivity. Put the most reactive metal first. most reactive least reactive [2] (b) Cobalt is a transition element. Lithium is an element in Group I of the Periodic Table. Describe two differences in the physical properties of cobalt compared to lithium. 1 …… 2 …… [2] (c) Brass and stainless steel are alloys. (i) Describe what is meant by the term alloy. …… [1] (ii) Name the two metals in brass. …… and …… [2] (iii) Give one use for stainless steel. …… [1] (d) (i) Deduce the number of protons, neutrons and electrons in the cobalt ion shown. 60Co3+ 27 number of protons …… number of neutrons …… number of electrons …… [3] (ii) State the charge on a neutron. …… [1] [Total: 12]

Question

A student investigates the reaction of magnesium with dilute sulfuric acid. (a) Complete the word equation for the reaction of magnesium with dilute sulfuric acid. magnesium + sulfuric acid + hydrogen [1] (b) The student sets up an experiment to investigate the rate of this chemical reaction. The student: • carries out the experiment at 25 °C using 2.00 g of magnesium ribbon and 25 cm3 of dilute sulfuric acid • measures the total volume of gas produced at regular time intervals • plots a graph of the results. Fig. 3.1 shows the graph of the student’s results. 100 80 60 total volume of hydrogen gas produced / cm3 40 20 0 0 100 200 300 400 500 time / s Fig. 3.1 (i) Draw a labelled diagram of the apparatus the student should use to carry out this investigation. [3] (ii) Deduce the total volume of hydrogen gas produced in the first 100 s of this reaction. volume of hydrogen = …… cm3 [1] (iii) Suggest why the reaction stops at 300 s. …… [1] (iv) The experiment is repeated at a higher temperature. All other conditions stay the same. Draw a line on the grid in Fig. 3.1 to show how the volume of hydrogen gas produced changes at a higher temperature. [3] (v) The student repeats the experiment using sulfuric acid of a lower concentration. All other conditions stay the same. Describe how the rate of the reaction differs when sulfuric acid of a lower concentration is used. …… [1] (vi) The student repeats the experiment using a catalyst. All other conditions stay the same. Describe how the rate of the reaction differs when a catalyst is used. …… [1] (c) Describe a test for hydrogen. test …… observations …… [1] [Total: 12] Question 4 starts on the next page.

Question

(a) Fig. 4.1 shows the displayed formula of compound B. H O H H H O H H O C C C C C C O H H H H Fig. 4.1 (i) On Fig. 4.1, draw a circle around the carboxylic acid functional group. [1] (ii) Deduce the molecular formula of compound B. …… [1] (iii) Explain why compound B is unsaturated. …… [1] (iv) Describe a test for an unsaturated compound. test …… observations …… [2] (b) Alkanes are hydrocarbons. (i) State the type of bonding in an alkane molecule. …… [1] (ii) Ethane reacts with chlorine in a substitution reaction. Draw the displayed formula of the organic product of this reaction. [1] (iii) State the meaning of the term hydrocarbon. …… [1] (c) Petroleum contains hydrocarbons. Name the process used to separate petroleum into its useful components. …… [1] (d) Complete Table 4.1 to show the name and use for some of the components in petroleum. Table 4.1 name use gasoline / petrol jet fuel bitumen [3] [Total: 12]

Question

This question is about iron and its compounds. (a) Fig. 5.1 shows the changes of the physical states of iron. melting C solid liquid gas D condensing Fig. 5.1 Name the changes of physical states C and D. C …… D …… [2] (b) Use the kinetic particle model to describe the arrangement and motion of the particles in liquid iron. arrangement …… motion …… [2] (c) Complete the symbol equation for the reaction of iron with oxygen. ……Fe + ……O2 Fe3O4 [2] (d) Iron can be obtained from iron ore in the blast furnace. (i) Name the main ore of iron used in the blast furnace. …… [1] (ii) State one reason why carbon is burned in the blast furnace. …… [1] (iii) Name the solid compound that forms when limestone undergoes thermal decomposition. …… [1] (e) Iron is used as a catalyst in the reaction shown. N2 + 3H2 2NH3 State the meaning of the symbol . …… [1] (f) Iron rusts when in contact with air and water. Name one barrier method used to prevent iron from rusting. …… [1] [Total: 11]

Question

This question is about acids and bases. (a) Dilute hydrochloric acid reacts with calcium carbonate powder. Name the three products formed in this reaction. 1 …… 2 …… 3 …… [3] (b) State the colour of methyl orange when it is added to dilute hydrochloric acid. …… [1] (c) For the test for halide ions, a dilute acid and aqueous silver nitrate are required. (i) Explain why the acid used must not be hydrochloric acid. …… [1] (ii) Suggest a suitable dilute acid that can be used for the test for halide ions. …… [1] (d) Barium carbonate is insoluble in water. Choose from the list one other compound that is insoluble in water. Tick (3) one box. ammonium carbonate lead(II) sulfate potassium hydroxide sodium nitrate [1] (e) Write the formula of the carbonate ion. …… [1] [Total: 8]

Question

(a) A list of common air and water pollutants is shown. methane nitrates oxides of nitrogen particulates plastics sewage Answer the following questions using only these pollutants. Each pollutant may be used once, more than once or not at all. State which pollutant: (i) contains harmful microbes that can cause disease …… [1] (ii) can be produced by the incomplete combustion of carbon‑containing fuels …… [1] (iii) is a gas formed from the decomposition of vegetation. …… [1] (b) A 250 cm3 sample of polluted water contains 3.5 mg of particulates. Calculate the mass of particulates present in 100 cm3 of this polluted water. mass of particulates = …… mg [1] (c) Sulfur dioxide in the atmosphere causes acid rain. State one method of reducing the emissions of sulfur dioxide to the atmosphere. …… [1] (d) Sulfur dioxide is a simple molecular compound. State two physical properties of simple molecular compounds. 1 …… 2 …… [2] [Total: 7]

Question

(a) Molten potassium chloride is electrolysed using inert electrodes. (i) Name the product formed at each electrode. product at positive electrode …… product at negative electrode …… [2] (ii) State the general name of the negative electrode used in electrolysis. …… [1] (b) Potassium forms a salt when added to ethanoic acid. Name the salt formed. …… [1] (c) Dilute ethanoic acid gives a yellow colour when tested with universal indicator. Choose from the list the pH value for dilute ethanoic acid. Draw a circle around your chosen answer. pH 1 pH 5 pH 7 pH 13 [1] (d) Ethanoic acid has the formula CH3COOH. Complete Table 8.1 to calculate the relative molecular mass of CH3COOH. Table 8.1 relative type of atom number of atoms atomic mass carbon 2 12 2 × 12 = 24 hydrogen 1 oxygen 16 relative molecular mass = …… [2] (e) A molecule of ethanol also contains two carbon atoms. (i) Ethanol can be manufactured by the addition of steam to ethene. In this process, a pressure of 60 atm is used. State two other conditions used in this process. 1 …… 2 …… [2] (ii) State one use of ethanol. …… [1] [Total: 10] 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 20 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.).