0620_s20_qp_42
A paper of Chemistry, 0620
Questions:
6
Year:
2020
Paper:
4
Variant:
2
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1
Give the name of the process that: occurs when a gas turns into a liquid occurs when a solid turns into a gas without first forming a liquid is used to separate a mixture of liquids with different boiling points is used to extract aluminium from aluminiumoxide is used to separate a mixture of amino acids. The symbols of the elements in Period2 of the PeriodicTable are shown. Li Be B C N O F Ne For each of the following, give the symbol of an element from Period2 which matches the description. Each element may be used once, more than once or not at all. Which element: combines with hydrogen to produce ammonia makes up approximately 21% of clean, dry air has atoms with only two electrons in the outer shell has atoms with only seven protons is a monoatomic gas is a soft metal stored in oil? 
1. States of matter  →  1.1. Solids, liquids and gases
8. The Periodic Table  →  8.1. Arrangement of elements
2. Atoms, elements and compounds  →  2.2. Atomic structure and the Periodic Table
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2
Fluorine forms both ionic and covalent compounds. Magnesium reacts with fluorine to form the ionic compound magnesiumfluoride. The electronic structures of an atom of magnesium and an atom of fluorine are shown. Mg F Complete the dot-and-cross diagrams to show the electronic structures of one magnesium ion and one fluoride ion. Show the charges on the ions. Mg F  What is the formula of magnesiumfluoride? Magnesiumfluoride does not conduct electricity when it is solid. What can be done to solid magnesiumfluoride to make it conduct electricity? In your answer explain why magnesiumfluoride conducts electricity when this change is made. Carbonyl fluoride, COF2, is a covalent compound. The structure of a molecule of COF2 is shown. C O F F Complete the dot-and-cross diagram to show the electron arrangement in a molecule of carbonylfluoride. Show outer shell electrons only. C O F F  The melting points of magnesiumfluoride and carbonylfluoride are shown. melting point / °C magnesium fluoride carbonyl fluoride –111 Explain, using your knowledge of structure and bonding, why magnesiumfluoride has a high melting point. Explain, using your knowledge of structure and bonding, why carbonylfluoride has a low melting point. 
2. Atoms, elements and compounds  →  2.5. Simple molecules and covalent bonds
2. Atoms, elements and compounds  →  2.4. Ions and ionic bonds
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3
Sulfuricacid is made from sulfur in a four-stage process. stage 1 Sulfur is converted into sulfurdioxide. stage 2 Sulfurdioxide is converted into sulfurtrioxide. stage 3 Sulfurtrioxide is converted into oleum. stage 4 Oleum is converted into sulfuricacid. How is sulfur converted into sulfurdioxide in stage1? Describe how sulfurdioxide is converted into sulfurtrioxide in stage2. Your answer should include: ● ● an equation for the reaction ● ● the temperature used ● ● the name of the catalyst used. The reaction in stage2 can reach equilibrium. What is meant by the term equilibrium? Sulfurtrioxide is converted into oleum, H2S2O7, in stage3. What is sulfurtrioxide reacted with to convert it into oleum? Oleum is converted into sulfuricacid in stage4. Write a chemical equation for the conversion of oleum, H2S2O7, into sulfuricacid. When copper is reacted with hot concentrated sulfuricacid, sulfurdioxide gas is formed. Balance the chemical equation for this reaction. Cu + H2SO4 → CuSO4 + SO2 + H2O Sulfurdioxide is a reducing agent. Give the colour change that occurs when excess sulfurdioxide is bubbled into acidified aqueous potassiummanganate(. starting colour of the solution final colour of the solution  When sulfuricacid reacts with ammonia the salt produced is ammoniumsulfate. Write the chemical equation for this reaction. Bariumsulfate is an insoluble salt. Bariumsulfate can be made from aqueous ammoniumsulfate using a precipitation reaction. Name a solution that can be added to aqueous ammoniumsulfate to produce a precipitate of bariumsulfate. Write an ionic equation for this precipitation reaction. Include state symbols. 
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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4
Oxygen is produced by the decomposition of hydrogen peroxide. Manganese(oxide is the catalyst for this reaction. What is meant by the term catalyst ? A student measures the volume of oxygen produced at regular time intervals using the apparatus shown. Large lumps of manganese(oxide are used. aqueous hydrogen peroxide gas syringe manganese(oxide catalyst A graph of the results is shown. volume of oxygen produced / cm3 time / s What happens to the rate of this reaction as time increases? In your answer, explain why the rate changes in this way. The experiment is repeated using the same mass of manganese(oxide. Powdered manganese(oxide is used instead of large lumps. All other conditions stay the same. Sketch a graph on the axes in to show how the volume of oxygen changes with time. In terms of particles, explain what happens to the rate of this reaction when the temperature is increased. The equation for the decomposition of hydrogen peroxide is shown. 2H2O2→ 2H2O+ O225.0 cm3 of aqueous hydrogenperoxide forms 48.0 cm3 of oxygen at room temperature and pressure (r.t.p.). Calculate the concentration of aqueous hydrogenperoxide at the start of the experiment using the following steps. ● ● Calculate the number of moles of oxygen formed.  mol ● ● Deduce the number of moles of hydrogen peroxide that decomposed.  mol ● ● Calculate the concentration of hydrogen peroxide in mol / dm3.  mol / dm3  Oxygen can also be produced by the decomposition of potassiumchlorate(, KCl O3. The only products of this decomposition are potassiumchloride and oxygen. Write a chemical equation for this decomposition. 
6. Chemical reactions  →  6.2. Rate of reaction
6. Chemical reactions  →  6.4. Redox
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5
Electrolysis of concentrated aqueous sodium chloride using inert electrodes forms chlorine, hydrogen and sodiumhydroxide. What is meant by the term electrolysis? Name a substance that can be used as the inert electrodes. Write an ionic half-equation for the formation of hydrogen during this electrolysis. Give the formulae of the four ions present in concentrated aqueous sodium chloride. Explain how sodiumhydroxide is formed during this electrolysis. 
4. Electrochemistry  →  4.1. Electrolysis
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6
Propane reacts with chlorine in a photochemical reaction as shown. C3H8 + Cl 2 → C3H7Cl + HCl What type of reaction is this? What condition is needed for this photochemical reaction to occur? Draw two structural isomers of compounds with the formula C3H7Cl. Show all of the atoms and all of the bonds.  Propene reacts with chlorine in an addition reaction as shown. C3H6 + Cl 2 → C3H6Cl 2 State why this is an addition reaction. The structures of the reactants and products of this reaction are shown. H C H H C H H C Cl Cl H + → H H C H H Cl Cl C H C H Some bond energies are shown in the table. bond bond energy in kJ / mol C–C C=C C–H C–Cl Cl –Cl Calculate the energy change for the reaction between propene and chlorine using the following steps. ● ● Calculate the energy needed to break the bonds.  kJ ● ● Calculate the energy released when bonds are formed.  kJ ● ● Calculate the energy change for the reaction between propene and chlorine.  kJ / mol  There are three functional groups in compoundA. C COOH H C compound A CH2OH H Name the homologous series of compounds that contains the following structures. C=C –OH –COOH  What would you observe when compoundA is added to: aqueous bromine aqueous sodiumcarbonate?  CompoundA can be used as a single monomer to produce two different polymers. Draw one repeat unit of the addition polymer formed from compoundA.  What type of condensation polymer is formed from compoundA? 
11. Organic chemistry  →  11.4. Alkanes
5. Chemical energetics  →  5.1. Exothermic and endothermic reactions
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