0620_w21_qp_43
A paper of Chemistry, 0620
Questions:
7
Year:
2021
Paper:
4
Variant:
3
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1
A list of substances is shown. ammonia bauxite carbon dioxide carbon monoxide ethanol hematite oxygen sodium chloride sulfur dioxide Answer the questions using the list of substances. Each substance may be used once, more than once or not at all. State which substance is: an element an ore of aluminium a gas that causes acid rain used as a fuel an ionic compound produced in the Haber process a product of respiration a toxic product of the incomplete combustion of hydrocarbons a gas produced in the test for nitrate ions. 
10. Chemistry of the environment  →  10.1. Water
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
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2
This question is about electrolysis. State the meaning of the term electrolyte. The table gives information about the electrolysis of two electrolytes. Carbon electrodes are used in each experiment. Complete the table to show the observations and products of electrolysis. positive electrode negative electrode electrolyte observations name of product observations name of product aqueous copper(sulfate colourless bubbles concentrated aqueous sodium bromide colourless bubbles hydrogen  Hydrogen is produced at the negative electrode during the electrolysis of concentrated aqueous sodiumbromide. Write the ionic half-equation for this reaction. State two reasons why carbon is suitable to use as an electrode.  Name the particle responsible for the conduction of electricity in the metal wires used in a circuit. 
4. Electrochemistry  →  4.1. Electrolysis
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3
Lead is a metallic element in GroupIV. One of the ores of lead is galena, which is an impure form of lead(sulfide, PbS. Lead also occurs in the ore cerussite, which contains lead(carbonate, PbCO3. Calculate the relative formula mass, Mr, of PbCO3.  Mr of PbCO3 = The Mr of PbS is 239. Calculate the percentage of lead by mass in PbS.  percentage of lead by mass in PbS = The percentage of lead by mass in PbCO3 is 77.5%. Use this information and your answer to to suggest whether it would be better to extract lead from PbCO3 or PbS. Give a reason for your answer. When lead(carbonate is heated it decomposes into lead(oxide, PbO, and carbondioxide. Write a chemical equation for this reaction. Lead(carbonate reacts with dilute nitricacid. One of the products is aqueous lead(nitrate, Pb(NO3)2. Write a chemical equation for this reaction. Lead(oxide and carbondioxide are oxides of GroupIV elements. Complete the diagram to show the electron arrangement in one molecule of CO2. Show only the outer electrons. O O C  The melting points of lead(oxide and carbondioxide are shown. melting point / °C lead(oxide carbon dioxide –56 Use your knowledge of structure and bonding to explain why lead(oxide has a much higher melting point than carbondioxide. Your answer should refer to: ● the types of particles involved ● the relative strength of the forces of attraction between the particles. Part of the reactivity series is shown. magnesium most reactive lead copper least reactive Aqueous lead(nitrate contains Pb2+ ions. Two experiments are carried out. In Experiment1, magnesium is added to aqueous lead(nitrate. In Experiment2, copper is added to aqueous lead(nitrate. Write an ionic equation for any reaction that occurs in each experiment. If no reaction occurs write ‘no reaction’. Experiment 1 Experiment 2  When lead(nitrate is heated it decomposes to produce the same gaseous products as when copper(nitrate is heated. One of the gaseous products is oxygen. Describe a test for oxygen. test observations  Name the other gaseous product. 
4. Electrochemistry  →  4.1. Electrolysis
9. Metals  →  9.4. Reactivity series
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4
Carbon is an important element. Carbon exists as the isotopes 12C 6 and 13C 6 . Complete the table. isotope number of protons in one atom number of electrons in one atom number of neutrons in one atom 12C 13C  Name two forms of the element carbon which have giant covalent structures. and The Avogadro constant is the number of particles in 1mole. The numerical value of the Avogadro constant is 6.02×1023. Calculate the number of molecules in 22.0 g of carbondioxide, CO2.  molecules Calculate the number of molecules in 6.00 dm3 of carbondioxide gas at room temperature and pressure.  molecules 
2. Atoms, elements and compounds  →  2.2. Atomic structure and the Periodic Table
3. Stoichiometry  →  3.3. The mole and the Avogadro constant
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5
Dilute sulfuricacid and aqueous sodiumhydroxide can be used to prepare sodiumsulfate crystals using a method that involves titration. 25.0 cm3 aqueous sodium hydroxide conical flask dilute sulfuric acid Suggest why universal indicator is not suitable for this titration. Name an indicator that can be used in this titration. 20.0 cm3 of dilute sulfuricacid neutralises 25.0 cm3 of 1.00 mol / dm3 aqueous sodiumhydroxide. At the end of the titration the conical flask contains aqueous sodiumsulfate with the dissolved indicator as an impurity. Describe how to prepare a pure sample of sodiumsulfate crystals from the original solutions of dilute sulfuricacid and aqueous sodiumhydroxide of the same concentrations. You are not required to give details of how to carry out the titration. Sodium hydrogensulfate, NaHSO4, dissolves in water to produce an aqueous solution, X, containing Na+, H+ and SO4 2– ions. State the observations when the following tests are done. A flame test is carried out on X. Copper(oxide is warmed with an excess of X. Acidified aqueous bariumnitrate is added to X. 
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
7. Acids, bases and salts  →  7.3. Preparation of salts
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6
A student investigates the decomposition of hydrogenperoxide in the presence of a catalyst of manganese(oxide. 2H2O2→ 2H2O+ O2State the meaning of the term catalyst. The diagram shows the equipment the student uses. aqueous hydrogen peroxide cotton wool balance catalyst of manganese(oxide The student uses this method: ● the catalyst is added to the aqueous hydrogen peroxide ● the stop-clock is started ● the mass of the flask and contents is recorded at regular time intervals. A graph of the mass of the flask and contents against time is shown. mass of the flask and contents / g time / s Suggest why the mass of the flask and contents decreases as time increases. Describe what happens to the rate of the reaction as time increases. The student repeats the experiment at a higher temperature. All other conditions stay the same. The rate of reaction increases. Explain, in terms of collisions between particles, why the rate of reaction increases at a higher temperature. Draw a line on the graph in for the experiment at a higher temperature. 
6. Chemical reactions  →  6.2. Rate of reaction
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7
Ethanol is a member of the homologous series of alcohols. Give two characteristics of members of a homologous series.  Ethanol can be manufactured from ethene. Ethene can be made from long chain hydrocarbons such as decane, C10H22. Ethene is then converted into ethanol. Name the process used to obtain ethene from long chain hydrocarbons such as decane, C10H22. Complete the chemical equation to show the formation of ethene from decane, C10H22. C10H22 → C4H8 + +  Write the chemical equation for the conversion of ethene into ethanol. Name the type of reaction occurring when ethene is converted into ethanol. Give one condition for the reaction in which ethene is converted into ethanol. Ethanol can also be produced by fermentation of carbohydrates such as glucose. Give two advantages of manufacturing ethanol by fermentation compared to manufacturing ethanol from ethene.  Under certain conditions ethene can react with chlorine to produce chloroethene. The structure of chloroethene is shown. C H H C H Cl The equation for the chemical reaction is shown. C2H4 + Cl 2 → C2H3Cl + HCl State the type of chemical reaction between ethene and chlorine that this equation shows. Chloroethene monomers can be converted into a polymer called poly. State the type of polymerisation that produces polyfrom chloroethene. Draw a section of the polymolecule made from two monomer molecules.  The structure of part of a polymer is shown. N C O N H H C O C O N H This polymer is made from one type of monomer only. Complete the diagram to show the structure of the monomer used to produce this polymer. Show all of the atoms and all of the bonds in the functional groups.  
11. Organic chemistry  →  11.6. Alcohols
11. Organic chemistry  →  11.8. Polymers
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