0620_w19_qp_43
A paper of Chemistry, 0620
Questions:
7
Year:
2019
Paper:
4
Variant:
3
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The table shows the melting points, boiling points and electrical conductivities of six substances D, E, F, G, H and I. substance melting point / °C boiling point / °C electrical conductivity when solid electrical conductivity when liquid D non-conductor non-conductor E non-conductor good conductor F –119 non-conductor non-conductor G good conductor good conductor H non-conductor non-conductor I –210 –196 non-conductor non-conductor Choose substances from the table which match the following descriptions. Each substance may be used once, more than once or not at all. Which substance is a liquid at 25 °C? Which substance is a gas at 25 °C? ������������������������������������������������������������������������������������ Which three substances contain simple molecules? Which substance could be a metal? Give a reason for your answer. substance reason  Which substance has a macromolecular structure? Give two reasons for your answer. substance reason 1 reason 2  Which substance is an ionic solid? Give one reason for your answer. substance reason  
2. Atoms, elements and compounds  →  2.4. Ions and ionic bonds
2. Atoms, elements and compounds  →  2.5. Simple molecules and covalent bonds
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Name the ore of aluminium which mainly consists of aluminium oxide. Aluminium is produced by the electrolysis of aluminium oxide dissolved in molten cryolite. negative electrode positive electrode molten mixture of aluminium oxide and cryolite aluminium waste gases Give two reasons why the electrolysis is done using a molten mixture of aluminiumoxide and cryolite instead of molten aluminiumoxide only.  Write ionic half-equations for the reactions occurring at the electrodes. positive electrode negative electrode  The anodes are made of carbon and have to be replaced regularly. Explain why the carbon anodes have to be replaced regularly. The positions of some common metals in the reactivity series are shown. most reactive magnesium aluminium least reactive copper When magnesium is placed in aqueous copper(sulfate a displacement reaction occurs immediately. Write an ionic equation for the reaction. Include state symbols. State two observations you would make when magnesium is placed in aqueous copper(sulfate.  When aluminium foil is added to aqueous copper(sulfate no immediate reaction takes place. Explain why. Aluminium powder reacts with iron(oxide to produce aluminiumoxide and iron. Write a chemical equation for this reaction. 
9. Metals  →  9.4. Reactivity series
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This question is about phosphorus and compounds of phosphorus. A phosphorus molecule contains four phosphorus atoms only. What is the formula of a phosphorus molecule? Phosphorus reacts with chlorine gas to produce phosphorus(chloride, PCl 3. Write a chemical equation for the reaction between phosphorus and chlorine to produce phosphorus(chloride, PCl 3. Complete the dot-and-cross diagram to show the electron arrangement in a molecule of phosphorus(chloride, PCl 3. Show outer shell electrons only. P Cl Cl Cl  Gaseous phosphorus(chloride, PCl 3, reacts with gaseous chlorine to form gaseous phosphorus(chloride, PCl 5. PCl 3+ Cl 2PCl 5The chemical equation for this reaction can be represented as shown. Cl Cl Cl P + Cl Cl Cl Cl Cl P Cl Cl Use the bond energies in the table to calculate the energy change, in kJ / mol, of the reaction. bond bond energy in kJ / mol P– Cl Cl – Cl ● ● Energy needed to break bonds.  kJ ● ● Energy released when bonds are formed.  kJ ● ● Energy change of reaction.  energy change = kJ / mol  Deduce whether the energy change for this reaction is exothermic or endothermic. Explain your answer. Under certain conditions the reaction reaches equilibrium. PCl 3+ Cl 2PCl 5State and explain the effect, if any, on the position of equilibrium if the pressure is increased. All other conditions are unchanged. Phosphine, PH3, is produced by the reaction between water and calciumphosphide, Ca3P2. Balance the chemical equation for this reaction. Ca3P2 + H2O Ca(OH)2 + PH3 The phosphonium ion, PH4 +, is similar to the ammonium ion. State the formula of the ammonium ion. ����������������������������������������������������������������������� Suggest the formula of phosphonium iodide. ��������������������������������������������������������������� Calciumphosphate contains the phosphate ion, PO4 3–. What is the formula of calciumphosphate? Phosphorus forms another compound with hydrogen with the following composition by mass: P, 93.94%; H, 6.06%. Calculate the empirical formula of the compound.  empirical formula = The compound has a relative molecular mass of 66. Deduce the molecular formula of the compound.  molecular formula = 
5. Chemical energetics  →  5.1. Exothermic and endothermic reactions
11. Organic chemistry  →  11.4. Alkanes
3. Stoichiometry  →  3.1. Formulae
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Nitrates such as ammoniumnitrate are used as fertilisers. The final stage in the production of ammoniumnitrate is shown in the equation. Ca(NO3)2 + 2NH3 + CO2 + H2O 2NH4NO3 + CaCO3 Calculate the maximum mass of ammonium nitrate that can be produced from 820 g of calciumnitrate, Ca(NO3)2, using the following steps. The relative formula mass, Mr, of calciumnitrate, Ca(NO3)2, = 164. ● ● Calculate the number of moles of Ca(NO3)2 in 820 g.  mol ● ● Deduce the number of moles of NH4NO3 produced.  mol ● ● Calculate the Mr of NH4NO3.  Mr of NH4NO3 = ● ● Calculate the maximum mass of ammoniumnitrate produced.  g 
10. Chemistry of the environment  →  10.2. Fertilisers
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
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This question is about sulfuricacid and substances that can be made from sulfuricacid. Sulfuric acid is a strong acid. What is meant by the term strong acid ? strong acid  Dilute sulfuricacid and aqueous sodiumhydroxide are used to make aqueous sodiumsulfate, Na2SO4, or aqueous sodiumhydrogensulfate, NaHSO4. The method includes use of the following apparatus. conical flask dilute sulfuric acid 25.0 cm3 of aqueous sodium hydroxide 25.0 cm3 of aqueous sodiumhydroxide of concentration 0.100 mol / dm3 was neutralised by 25.0 cm3 of dilute sulfuricacid of concentration 0.0500 mol / dm3. The equation for the reaction is shown. This is reaction1. 2NaOH+ H2SO4Na2SO4+ 2H2O reaction 1 The same technique and the same solutions can be used to make aqueous sodiumhydrogensulfate. The equation for the reaction is shown. This is reaction2. NaOH+ H2SO4NaHSO4+ H2O reaction 2 Complete the table to calculate the volume of dilute sulfuricacid that reacts with 25.0 cm3 of aqueous sodiumhydroxide in reaction2. volume of 0.0500 mol / dm3 dilute sulfuric acid in cm3 volume of 0.100 mol / dm3 aqueous sodium hydroxide in cm3 reaction 1 25.0 25.0 reaction 2 25.0  Aqueous sodium hydrogen sulfate, NaHSO4, contains the ions Na+, H+and SO4 2–. Describe what you would see if the following experiments were done. A flame test was done on aqueous sodiumhydrogensulfate. Solid copper(oxide was added to aqueous sodiumhydrogensulfate and the mixture was warmed. A test can be done to show the presence of SO4 2–by adding acidified aqueous bariumchloride or acidified aqueous bariumnitrate. State the observation that would show that SO4 2– is present. Write an ionic equation for the reaction that occurs if SO4 2– is present. Include state symbols. 
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
7. Acids, bases and salts  →  7.1. The characteristic properties of acids and bases
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Addition polymerisation and condensation polymerisation are two types of polymerisation. Which functional group is present in all the monomers which are used to make addition polymers? Part of an addition polymer is shown. C CH3 H C CH3 H C CH3 H C CH3 H C CH3 H C CH3 H How many monomer units are needed to make the part of the addition polymer shown? Draw the structure of the monomer that is used to make this addition polymer. Show all of the atoms and all of the bonds. Name the monomer. name  State the empirical formula of: the monomer the polymer.  Complex carbohydrates are natural condensation polymers. They can be broken down into colourless monomers which can then be separated and identified. X is a complex carbohydrate. Starting with a sample of X, describe how to produce, separate, detect and identify the monomers which make it up. Your answer should include: ● ● the name of the process used to break down X into its monomers ● ● two types of substance that can be used to break down X ● ● the name of the process used to separate the monomers ● ● the method used to detect the monomers after they have been separated ● ● the method used to identify the monomers after they have been separated and detected. Synthetic polyamides are condensation polymers. Name a synthetic polyamide. Synthetic polyamides can be made by reacting carboxylic acids with amines. Name the other substance that is produced in this reaction. 
11. Organic chemistry  →  11.8. Polymers
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