0620_w21_qp_32
A paper of Chemistry, 0620
Questions:
8
Year:
2021
Paper:
3
Variant:
2
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1
A list of formulae is shown. CaCO3 CaO Cl 2 CH4 C2H5OH C2H6 CuSO4 H2 H2O MgO NaCl SO2 Answer the following questions using these formulae. Each formula may be used once, more than once or not at all. State which formula represents: a compound that is the main constituent of natural gas an element that is used in water treatment an element that bleaches damp litmus paper a compound that contains an ion with a single negative charge a hydrocarbon that is formed by the decomposition of vegetation. Complete the dot-and-cross diagram to show the electron arrangement in a molecule of water. H H O  State whether calciumoxide is a basic oxide or an acidic oxide. Give a reason for your answer. 
3. Stoichiometry  →  3.1. Formulae
6. Chemical reactions  →  6.4. Redox
7. Acids, bases and salts  →  7.1. The characteristic properties of acids and bases
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2
The table shows the masses of some of the ions in 1000 cm3 of water taken from a lake. name of ion formula of ion mass of ion in 1000 cm3 of lake water / mg calcium Ca2+ 0.41 chloride Cl – 4.40 magnesium Mg2+ 0.39 NO3 – 0.03 potassium K+ 0.30 silicate SiO3 2– 0.02 Na+ 2.90 sulfate SO4 2– 2.80 Answer these questions using only the information in the table. State which of the negative ions has the lowest concentration. Name the compound containing Na+ and NO3 – ions. Calculate the mass of chloride ions in 250 cm3 of lake water.  mass = mg Describe a test for sulfate ions. test observations  Citricacid is also present in the lake water. The structure of citric acid is shown. O O H O C C C C C C H H O O O O H H H H H Deduce the number of carboxylic acid groups in one molecule of citricacid. The formula of citricacid is C6H8O7. Complete the table to calculate the relative molecular mass of citricacid. type of atom number of atoms relative atomic mass carbon 6 × 12 = 72 hydrogen oxygen  relative molecular mass =  
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
3. Stoichiometry  →  3.1. Formulae
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3
Iron is extracted from iron ore in a blast furnace. Name an ore of iron. Complete the chemical equation for the reduction of iron(oxide in the blast furnace. Fe2O3 + CO → Fe + 3CO2 State the meaning of the term reduction. Calciumcarbonate is added to the blast furnace. The calciumcarbonate undergoes thermal decomposition. State the meaning of the term thermal decomposition. Iron can be made into stainless steel. Give one use of stainless steel. Describe one advantage of stainless steel compared with pure iron. The symbol for an isotope of iron is shown. 57Fe Deduce the number of electrons, neutrons and protons in one atom of this isotope of iron. number of electrons number of neutrons number of protons  Iron is a good conductor of heat and electricity. Give two other physical properties of iron that are characteristic of all metals.  Iron rusts. Name the two substances needed for iron to rust.  
9. Metals  →  9.6. Extraction of metals
9. Metals  →  9.5. Corrosion of metals
9. Metals  →  9.4. Reactivity series
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4
The table shows some properties of the GroupI elements. element melting point / °C density in g / cm3 observations during reaction with water lithium 0.53 sodium rapid bubbling no flame potassium 0.86 rapid bubbling lilac flame rubidium 1.53 very rapid bubbling red flame caesium 1.88 explodes francium Complete the table by predicting: ● the melting point of potassium ● the density of francium. Describe the observations when lithium reacts with water. Deduce the electronic structure of sodium. Use the Periodic Table to help you. Explain why a potassium ion has a single positive charge. Sodium reacts with water to produce aqueous sodiumhydroxide and a gas which ‘pops’ with a lighted splint. Complete the chemical equation for this reaction. 2Na + 2H2O → NaOH +  Choose one value from the list that best describes the pH of aqueous sodiumhydroxide. Draw a circle around the correct answer. pH 1 pH 4 pH 7 pH 14 
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
9. Metals  →  9.4. Reactivity series
8. The Periodic Table  →  8.1. Arrangement of elements
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5
The table shows the structures of some organic compounds. compound structure of compound homologous series G H C H H H C C H H H H alkane H H C H H C H H C H H O H J H C H H C H H C H Complete the table by naming the homologous series. The first one has been done for you. Draw the structure of a compound containing two carbon atoms which belongs to the same homologous series as compoundH. Show all of the atoms and all of the bonds.  Describe the colour change when an excess of compoundJ is added to aqueous bromine. from to CompoundJ can be obtained by cracking petroleum fractions. State the conditions needed for cracking. Complete this sentence about cracking using a word from the list. bitumen hydrogen oxygen petroleum The chemicals manufactured by cracking include alkanes, alkenes and .  CompoundG is propane. Complete the word equation for the complete combustion of propane. propane + oxygen → +  CompoundJ can form polymers. State the meaning of the term polymer. Nylon is also a polymer. Give one use of nylon. Describe one pollution problem caused by non-biodegradable plastics. 
11. Organic chemistry  →  11.2. Naming organic compounds
11. Organic chemistry  →  11.5. Alkenes
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6
The diagrams show part of the structures of potassiumiodide and bromine at room temperature and pressure. K+ I– K+ I– K+ I– K+ I– I– K+ K+ I– Br Br Br Br Br Br Br Br Br Br Br Br Br Br Br Br Describe the physical properties of these substances in terms of: ● volatility potassium iodide bromine ● solubility in water potassium iodide bromine ● electrical conductivity when molten . potassium iodide bromine  Molten potassiumiodide is electrolysed using carbon electrodes. Name the substance produced at the positive electrode. Aqueous potassiumiodide reacts with aqueous bromine. Complete the word equation for this reaction. potassium iodide + bromine → +  Explain in terms of the reactivity of the halogens why aqueous potassiumchloride does not react with aqueousbromine. Name the change of state when liquid bromine changes to solid bromine. 
11. Organic chemistry  →  11.5. Alkenes
4. Electrochemistry  →  4.1. Electrolysis
6. Chemical reactions  →  6.4. Redox
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7
This question is about sulfur and compounds of sulfur. Use the kinetic particle theory to describe the differences between sulfur gas and solid sulfur in terms of: ● the arrangement of the particles ● the separation of the particles.  Give the major use of sulfur in industry. Sulfurdioxide is a pollutant in the air that contributes to acid rain. State one adverse effect of sulfur dioxide on health. Name one other oxide that contributes to acid rain. Sulfurdioxide reacts with water to produce sulfurous acid. The reaction is reversible. Draw the symbol for a reversible reaction in the box. SO2 + H2O H2SO3 The equation for the reaction of sodiumsulfite with zinc is shown. Na2SO3 + 3Zn → Na2S + 3ZnO Explain how this equation shows that zinc is oxidised. 
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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8
A student investigated the reaction of small pieces of calciumcarbonate with dilute hydrochloricacid. The hydrochloric acid was in excess. CaCO3 + 2HCl → CaCl 2 + CO2 + H2O The rate of reaction is found by measuring the decrease in the mass of the reaction mixture with time. The results are shown on the graph. time / s mass of reaction mixture / g Deduce the time taken from the beginning of the experiment for the mass of the reaction mixture to decrease by 1.0 g.  time = s The experiment was repeated using dilute hydrochloricacid of a higher concentration. All other conditions stayed the same. Draw a line on the grid to show how the mass of the reaction mixture changes with time using acid of a higher concentration. Describe the effect each of the following has on the rate of reaction of calciumcarbonate with hydrochloricacid. All other conditions stay the same. ● The reaction is carried out at a higher temperature. ● The reaction is carried out using large pieces of calciumcarbonate instead of small pieces of calciumcarbonate.  When 0.44 g of calciumcarbonate is used, 100 cm3 of carbondioxide gas is formed. Calculate the mass of calciumcarbonate needed to produce 25 cm3 of carbondioxide gas.  mass of calcium carbonate = g The table compares the reaction of four metals with dilute hydrochloricacid. metal observations iron bubbles produced slowly magnesium bubbles produced very rapidly nickel bubbles produced very slowly silver no bubbles produced Put the four metals in order of their reactivity. Put the least reactive metal first. least reactive most reactive  
6. Chemical reactions  →  6.2. Rate of reaction
9. Metals  →  9.4. Reactivity series
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