0620_w19_qp_42
A paper of Chemistry, 0620
Questions:
5
Year:
2019
Paper:
4
Variant:
2
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1
The Periodic Table is very useful to chemists. Refer only to elements with atomic numbers 1 to 36 in the Periodic Table provided when answering Question1. Use information from the Periodic Table provided to identify one element which: has atoms with exactly 9 protons has atoms with 0 neutrons has atoms with exactly 23 electrons has atoms with an electronic structure of 2,8,6 forms ions with a charge of 3– containing 18 electrons forms ions with a charge of 2+ containing 10 electrons has a relative atomic mass that shows it has at least two isotopes. State which metal in the first 36 elements: is the GroupI element which reacts most vigorously with water reacts with air to form lime. One element in the first 36 elements is used as the fuel in a fuel cell. Name this element. Write the overall chemical equation for the reaction which occurs when the element in reacts in a fuel cell. 
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
The gases Ar, CO2, N2 and O2 are in clean, dry air. CO, NO, NO2 and SO2 are gases commonly found in polluted air. What percentage of clean, dry air is N2? Give your answer to the nearest whole number.  % Name the process used to separate O2 from clean, dry air. State one major adverse effect of the pollutant SO2. NO and NO2 are produced in car engines. Describe how oxides of nitrogen form in a car engine. Many cars have catalytic converters in their exhaust systems. In a catalytic converter, most of the CO and NO formed in a car engine is changed into less harmful products. Identify these products and state the metal catalyst used. products catalyst  CO is formed from the incomplete combustion of fossil fuels such as methane. Write a chemical equation to show the incomplete combustion of methane. The CO2 in air is part of the carbon cycle. The scheme shows a simple representation of part of the carbon cycle. carbon dioxide in the air animals glucose found in green plants feeding A B State the scientific terms for each of processA and processB. A B  Plants convert glucose into complex carbohydrates. A unit of glucose can be represented as HO OH. Complete the diagram to show the complex carbohydrate formed from three units of glucose. Show all of the atoms and all of the bonds in the linkages.  Complex carbohydrates break down to form simple sugars. State two ways that complex carbohydrates can be broken down into simple sugars.  Name a suitable technique for separating and identifying the individual sugars formed when complex carbohydrates are broken down. 
10. Chemistry of the environment  →  10.3. Air quality and climate
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3
Ammonia is an important chemical. Ammonia is manufactured by the Haber process. The reaction is reversible. What is the sign for a reversible reaction? State the essential conditions for the manufacture of ammonia by the Haber process starting from hydrogen and nitrogen. Include a chemical equation to show the reaction which occurs. Name one raw material which is a source of the hydrogen used in the Haber process. Ammonia is a base and reacts with sulfuricacid to form the salt, ammoniumsulfate. What is meant by the term base? Name the industrial process used to manufacture sulfuricacid. Write a chemical equation for the reaction between ammonia and sulfuricacid. When aqueous ammonia is added to aqueous iron(sulfate a green precipitate is seen. This green precipitate turns red-brown at the surface. Name the green precipitate. Suggest why the green precipitate turns red-brown at the surface. State what happens when an excess of aqueousammonia is added to the green precipitate. Ammonia reacts with oxygen as shown. 4NH3+ 5O24NO+ 6H2OCalculate the volume of oxygen at room temperature and pressure, in dm3, that reacts with 4.80 dm3 of ammonia.  volume = dm3 The chemical equation for the reaction can be represented as shown. H N H H + O O H O H + N O Use the bond energies in the table to calculate the energy change, in kJ / mol, which occurs when one mole of NH3 reacts. bond N–H O=O N=O O–H bond energy in kJ / mol ● ● Energy needed to break bonds.  kJ ● ● Energy released when bonds are formed.  kJ ● ● Energy change when one mole of NH3 reacts.  energy change = kJ / mol  
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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4
Many substances conduct electricity. Identify all the particles responsible for the passage of electricity in: ● graphite ● magnesium ribbon ● molten copper(bromide.  A student used the following apparatus to electrolyse concentrated aqueous sodiumchloride using inert electrodes. + – inert electrodes concentrated aqueous sodium chloride Suggest the name of a metal which could be used as the inert electrodes.  Name the gas formed at the positive electrode. Write an ionic half-equation for the reaction occurring at the negative electrode. Include state symbols. How, if at all, does the pH of the solution change during the electrolysis? Explain your answer. A student used the following electrochemical cell. The reading on the voltmeter was +1.10 V. copper electrode dilute sulfuric acid zinc electrode V voltmeter Draw an arrow on the diagram to show the direction of electron flow. Suggest the change, if any, in the voltmeter reading if the zinc electrode was replaced with an iron electrode. Explain your answer. The zinc electrode was replaced with a silver electrode. The reading on the voltmeter was –0.46 V. Suggest why the sign of the voltmeter reading became negative. 
4. Electrochemistry  →  4.1. Electrolysis
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5
Methanol, CH3OH, is a member of the homologous series of alcohols. Methanol can be made from methane in a two-step process. step 1 Methane is reacted with chlorine gas to produce chloromethane, CH3Cl. step 2 CH3Cl is reacted with sodiumhydroxide to produce CH3OH and one other product. What conditions are needed in step1? Write the chemical equation for the reaction which occurs in step1. State the type of organic reaction occurring in step1. Complete the chemical equation for step2. CH3Cl + NaOH CH3OH + Draw a dot-and-cross diagram to show the electron arrangement in a molecule of methanol. Show outer shell electrons only. C H H O H H  Methanol reacts with propanoicacid to form an ester with a molecular formula C4H8O2. Name the ester formed when methanol reacts with propanoicacid. Name one other substance formed when methanol reacts with propanoic acid. Draw the structure of an ester which is a structural isomer of the ester named in . Show all of the atoms and all of the bonds.  State the conditions needed to form an ester from a carboxylicacid and an alcohol. 
11. Organic chemistry  →  11.2. Naming organic compounds
11. Organic chemistry  →  11.7. Carboxylic acids
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