0620_m20_qp_42
A paper of Chemistry, 0620
Questions:
5
Year:
2020
Paper:
4
Variant:
2
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1
Petroleum is a useful natural resource. The diagram shows how petroleum can be separated into useful substances. kerosene fraction A gasoline fraction refinery gas diesel oil fuel oil fraction petroleum lubricating oil fraction B What is the name of the separation process shown in the diagram? Name the fraction leaving at: A B  Refinery gas is a mixture of hydrocarbons. One refinery gas is butane, C4H10. Suggest the names of two other refinery gases. and Write the chemical equation for the complete combustion of butane. Name the toxic gas produced by the incomplete combustion of butane. Gasoline and kerosene are both fuels. They have different properties. Describe the differences in the properties given. viscosity of the fuel flammability of the fuel  What difference in the molecules of gasoline and kerosene causes these differences in properties? Hydrogen fuel cells can be used to power vehicles. Write the word equation for the overall reaction that takes place in a hydrogen fuel cell. 
11. Organic chemistry  →  11.3. Fuels
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2
Aluminium is extracted from its ore. The ore is converted into pure aluminiumoxide, which then undergoes electrolysis as shown. + + + – anodes power supply electrolyte molten aluminium wires cathode Name an ore of aluminium. What is meant by the term electrolysis? Aluminiumoxide has a melting point of about 2000 °C, but the electrolysis process operates at about 900 °C. Name the compound added to aluminiumoxide to reduce the operating temperature. Suggest one benefit to the environment of reducing the operating temperature. Write the ionic half-equation for the reaction taking place at: the negative electrode the positive electrode  Explain why the anodes need frequent replacement. Aluminiumoxide reacts with acids and with alkalis. What term is used to describe an oxide that reacts with acids and with alkalis? Aluminiumoxide reacts with dilute sulfuric acid to form a salt. State the name and write the formula of the salt formed. name formula  Aluminiumoxide reacts with dilute sodiumhydroxide to form a salt and one other product. Name the other product. Aluminiumhydroxide, Al (OH)3, decomposes when heated to form aluminiumoxide and water. Write the chemical equation for this reaction. Suggest the names of two other aluminium compounds that decompose when heated to form aluminiumoxide. 
9. Metals  →  9.6. Extraction of metals
4. Electrochemistry  →  4.1. Electrolysis
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3
The Periodic Table is a method of classifying elements. Identify the element which is in GroupVI and Period4. Calcium is in GroupII and chlorine is in GroupVII of the PeriodicTable. Explain, in terms of number of outer shell electrons and electron transfer, how calcium atoms and chlorine atoms form ions. Give the formulae of the ions formed. GroupV chlorides are covalent molecules. The boiling points of some GroupV chlorides are shown. chloride boiling point / °C NCl 3 PCl 3 AsCl 3 SbCl 3 Suggest the approximate boiling point of PCl 3. Explain the trend in boiling points in terms of attractive forces between particles. Complete the dot-and-cross diagram to show the electron arrangement in a molecule of PCl 3. Show outer electrons only. P Cl Cl Cl  PCl 3 reacts with chlorine, Cl 2, to form PCl 5. This reaction is exothermic and reaches an equilibrium. PCl 3+ Cl 2PCl 5Describe two features of an equilibrium. State the effect, if any, on the position of this equilibrium when the following changes are made. Explain your answers. temperature is increased pressure is increased  Explain, in terms of particles, what happens to the rate of the forward reaction when the reaction mixture is heated. PCl 5 reacts with lithium fluoride, LiF, to form LiPF6. PCl 5 + 6LiF → LiPF6 + 5LiCl Calculate the mass of LiF needed to form 3.04 g of LiPF6 using the following steps. ● ● Calculate the number of moles of LiPF6 formed. [Mr: LiPF6, 152]  number of moles = ● ● Deduce the number of moles of LiF needed.  number of moles = ● ● Calculate the mass of LiF needed.  mass = g  Lithium fluoride has ionic bonding. What is an ionic bond? Give two physical properties of ionic compounds. 
9. Metals  →  9.4. Reactivity series
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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4
Iron is a typical transition element. Iron: ● ● acts as a catalyst ● ● forms coloured compounds ● ● has more than one oxidation state. Name one major industrial process that uses iron as a catalyst and name the product made in this process. process product made  When aqueous sodiumhydroxide is added to aqueous iron(sulfate, a precipitate forms. What colour is this precipitate? Write the ionic equation for this reaction. Include state symbols. Iron(sulfate can be converted to iron(sulfate by potassiummanganate(at room temperature. What is the role of potassiummanganate(in this reaction? What condition must be used for this reaction to occur? In terms of electron transfer, what happens to the iron(ions in this reaction? State the colour change seen during this reaction. from purple to Deduce the charge on the iron ion in each of these compounds. FeF3 Fe(NO3)3  
8. The Periodic Table  →  8.4. Transition elements
9. Metals  →  9.5. Corrosion of metals
6. Chemical reactions  →  6.4. Redox
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5
There are two types of polymers. Addition polymers are made from many identical small units. What is the term used to describe these small units? A section of an addition polymer is shown. C H H C CH3 CH3 C H H C CH3 CH3 C H H C CH3 CH3 Draw the structure of the small unit used to make this addition polymer. Show all of the atoms and all of the bonds.  Polyamides are condensation polymers. What does the term condensation mean when used to describe this type of polymer? A polyamide can be made from two different molecules. A simplified structure of octanedioic acid is shown. C C O O O O H H A simplified structure of 1,6-diaminohexane is shown. N N H H H H Complete the diagram to show a section of polyamide manufactured from octanedioic acid and 1,6-diaminohexane. Include all of the atoms and all of the bonds in the linkages.  State the name of a synthetic polyamide. 
11. Organic chemistry  →  11.8. Polymers
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