0620_s12_qp_31
A paper of Chemistry, 0620
Questions:
8
Year:
2012
Paper:
3
Variant:
1
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1
For Examiner’s Use The diagram below shows part of the Water Cycle. sea H2OH2OSun cloud H2Oland rain State the name of each of the following changes of state. H2O→ H2Oname H2O→ H2Oname Which one of the above changes of state is exothermic? Explain your choice. The rain drains into rivers and then into reservoirs. Describe how water is treated before it enters the water supply. Explain how acid rain is formed. For Examiner’s Use Fish live in water which is neutral (neither acidic nor alkaline). Acid rain decreases the pH of water in lakes and rivers. Both of the bases, calcium oxide and calcium carbonate, can neutralise this acid and increase the pH. Explain why calcium carbonate is a better choice.
10. Chemistry of the environment  →  10.1. Water
9. Metals  →  9.4. Reactivity series
7. Acids, bases and salts  →  7.1. The characteristic properties of acids and bases
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2
Three ways of making salts are ● titration using a soluble base or carbonate ● neutralisation using an insoluble base or carbonate ● precipitation. Complete the following table of salt preparations. method reagent 1 reagent 2 salt titration sodium nitrate neutralisation nitric acid copper(nitrate precipitation silver(chloride neutralisation sulfuric acid zinc(carbonate Write an ionic equation with state symbols for the preparation of silver(chloride. Complete the following equation. ZnCO3 + H2SO4 → + +
7. Acids, bases and salts  →  7.3. Preparation of salts
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3
For Examiner’s Use The Group I metals show trends in both their physical and chemical properties. How do their melting points vary down the Group? Which element in the Group has the highest density? All Group I metals react with cold water. Complete the following equation. Rb + H2O → + Lithium reacts with nitrogen to form the ionic compound, lithium nitride. State the formula of the lithium ion. …… Deduce the formula of the nitride ion. …… In all solid ionic compounds, the ions are held together in a lattice. Explain the term lattice. What is the ratio of lithium ions to nitride ions in the lattice of lithium nitride? Give a reason for your answer. lithium ions : nitride ions
8. The Periodic Table  →  8.2. Group I properties
8. The Periodic Table  →  8.1. Arrangement of elements
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4
Vanadium is a transition element. It has more than one oxidation state. The element and its compounds are often used as catalysts. Complete the electron distribution of vanadium by inserting one number. 2 + 8 + + 2 Predict three physical properties of vanadium which are typical of transition elements. 1. 2. 3. For Examiner’s Use Vanadium(oxide is used to catalyse the exothermic reaction between sulfur dioxide and oxygen in the Contact Process. 2SO2 + O2 2SO3 The rate of this reaction can be increased either by using a catalyst or by increasing the temperature. Explain why a catalyst is used and not a higher temperature. The oxidation states of vanadium in its compounds are V(+5), V(+4), V(+3) and V(+2). The vanadium(ion can behave as a reductant or an oxidant. Indicate on the following equation which reactant is the oxidant. 2V3+ + Zn → 2V2+ + Zn2+ Which change in the following equation is oxidation? Explain your choice. V3+ + Fe3+ → V4+ + Fe2+
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
6. Chemical reactions  →  6.4. Redox
8. The Periodic Table  →  8.4. Transition elements
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5
Reactive metals tend to have unreactive compounds. The following is part of the reactivity series. sodium most reactive calcium zinc copper silver least reactive Sodium hydroxide and sodium carbonate do not decompose when heated. The corresponding calcium compounds do decompose when heated. Complete the following equations. calcium carbonate → + Ca(OH)2 → + For Examiner’s Use All nitrates decompose when heated. The equation for the thermal decomposition of silver(nitrate is given below. 2AgNO3 → 2Ag + 2NO2 + O2 What are the products formed when copper(nitrate is heated? Complete the equation for the action of heat on sodium nitrate. NaNO3 → + Which of the metals in the list on page 5 have oxides which are not reduced by carbon? Choose from the list on page 5, metals whose ions would react with zinc.
9. Metals  →  9.4. Reactivity series
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6
Butane is an alkane. It has the following structural formula. C H H H H C H H C H H C H H The equation for the complete combustion of butane is given below. Insert the two missing volumes. 2C4H10+ 13O2→ 8CO2+ 10H2O40 volume of gas / cm3 Butane reacts with chlorine to form two isomers of chlorobutane. What type of reaction is this? Explain the term isomer. For Examiner’s Use Draw the structural formulae of these two chlorobutanes. One of the chlorobutanes reacts with sodium hydroxide to form butan-1-ol. Butan-1-ol can be oxidised to a carboxylic acid. State a reagent, other than oxygen, which will oxidise butan-1-ol to a carboxylic acid. Name the carboxylic acid formed. Butan-1-ol reacts with ethanoic acid to form an ester. Name this ester and give its structural formula showing all the individual bonds. name structural formula
11. Organic chemistry  →  11.7. Carboxylic acids
11. Organic chemistry  →  11.2. Naming organic compounds
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7
For Examiner’s Use Plastics are polymers. They are formed from their monomers by polymerisation. Two methods for the disposal of waste plastics are ● burning ● recycling. Describe one advantage and one disadvantage of each method. burning recycling There are two types of polymerisation reaction. Give their names and explain the differences between them. Give the structural formula of a polymer which is formed from two different monomers.
11. Organic chemistry  →  11.8. Polymers
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8
For Examiner’s Use Iron and steel rust when exposed to water and oxygen. Rust is hydrated iron(oxide. The following cell can be used to investigate rusting. – + V oxygen bubbled on to electrode iron electrode B iron electrode A water iron(oxide electron flow What is a cell? Which electrode will be oxidised and become smaller? Explain your choice. What measurements would you need make to fi nd the rate of rusting of the electrode you have chosen in ? Suggest an explanation why the addition of salt to the water increases the rate of rusting. For Examiner’s Use A sample of rust had the following composition: 51.85 g of iron 22.22 g of oxygen 16.67 g of water. Calculate the following and then write the formula for this sample of rust. number of moles of iron atoms, Fe = number of moles of oxygen atoms, O = number of moles of water molecules, H2O = simplest mole ratio Fe : O : H2O is : : formula for this sample of rust is
9. Metals  →  9.5. Corrosion of metals
9. Metals  →  9.6. Extraction of metals
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