0620_w20_qp_41
A paper of Chemistry, 0620
Questions:
7
Year:
2020
Paper:
4
Variant:
1
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1
This question is about elements. aluminium carbon iron hydrogen oxygen silicon sodium sulfur Answer the following questions about these elements. Each element may be used once, more than once or not at all. Name the element that can be used as a fuel. Name the element that forms an oxide with a similar structure to diamond. Name the element that forms an amphoteric oxide. Name the element that has oxidation states of +2 and +3. Name the element extracted from bauxite. Name the element that has atoms with the electronic structure 2,6. Iron rusts when it is in contact with oxygen and water. Explain how sacrificial protection prevents rusting. State one other method of rust prevention. 
9. Metals  →  9.5. Corrosion of metals
9. Metals  →  9.1. Properties of metals
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2
Zinc is extracted from an ore containing zinc sulfide. State the name of this zinc ore. This ore is converted to zincoxide, ZnO. Zincoxide is then reacted with carbon. Write a chemical equation for the reaction of zincoxide with carbon. State what type of chemical change happens to the zinc in zincoxide in this reaction. Explain your answer. chemical change explanation  Explain why aluminium is not extracted from aluminiumoxide by heating with carbon. Suggest an alternative method for the extraction of zinc from zincoxide. Brass is an alloy of zinc. Explain, in terms of particles, why brass is harder than pure zinc. 
9. Metals  →  9.6. Extraction of metals
9. Metals  →  9.5. Corrosion of metals
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3
Aqueous ammoniumsulfate, (NH4)2SO4, is warmed with aqueous sodiumhydroxide. The pungent-smelling gas ammonia, NH3, is produced. Balance the equation for this reaction. (NH4)2SO4 + NaOH → NH3 + H2O + Na2SO4 A 2.8 g sample of impure ammoniumsulfate is found to contain 0.7 g of impurities. Calculate the percentage of ammoniumsulfate in this sample.  percentage of ammonium sulfate = % Describe a test for ammonia gas. test result  Ammonia gas is prepared at the front of a laboratory. The pungent smell of ammonia spreads throughout the laboratory slowly. Name the process that occurs when ammonia gas spreads throughout the laboratory. Explain, using ideas about particles, why ammonia gas spreads throughout the laboratory. Explain why carbondioxide gas, CO2, will spread throughout the laboratory at a slower rate than ammonia gas, NH3. Ammonia is produced in the Haber process. The equation for the reaction is shown. N2+ 3H2→ 2NH3In the Haber process, a temperature of 450 °C and a pressure of 200atmospheres are used in the presence of finely‑divided iron. A larger equilibrium yield of ammonia would be produced if a lower temperature and a higher pressure are used. Explain why a lower temperature and a higher pressure are not used. lower temperature higher pressure  State the role of iron in the Haber process. Ammonia is a weak base. Explain the meaning of the term base. Suggest the pH of aqueous ammonia. 
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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4
Air is a mixture of gases. State the percentage of clean dry air which is oxygen. Give your answer to the nearest whole number.  % Oxygen and nitrogen are useful gases that can be obtained from air. Name the process used to separate oxygen and nitrogen from liquid air. State the property of oxygen and nitrogen that allows these gases to be separated using this process. Carbondioxide, CO2, is a covalent molecule. Complete the diagram to show the electron arrangement in one molecule of CO2. Show only the outer electrons. C O O  The graph shows the concentration of carbondioxide in the atmosphere over a 60‑year period, measured in parts per million . concentration of carbon dioxide / ppm year The data shown in the graph is of global concern. Explain why. Name the process in the carbon cycle by which plants remove carbon dioxide from the atmosphere. 
10. Chemistry of the environment  →  10.3. Air quality and climate
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Dilute sulfuricacid is electrolysed using the apparatus shown in the diagram. power supply inert electrodes dilute sulfuric acid + – State what is meant by the term electrolysis. Explain why inert electrodes are used. Name the products formed at each electrode. negative electrode positive electrode  Write an ionic half‑equation for the reaction at the negative electrode. Sulfuric acid is manufactured using the Contact process. This manufacture involves four stages. Stage1 involves the combustion of sulfur to form sulfurdioxide. Write the chemical equation for stage1. The equation for stage2 is shown. 2SO2+ O22SO3The reaction can reach equilibrium. Explain what is meant by the term equilibrium. The energy level diagram for the forward reaction in stage2 is shown. energy progress of reaction 2SO2+ O22SO3Explain what the diagram shows about the energy changes in the forward reaction. In stage3 sulfurtrioxide, SO3, is converted to oleum, H2S2O7. In stage4 oleum reacts to form sulfuricacid, H2SO4. State what oleum reacts with in stage4. A sample of sulfuricacid, H2SO4, has a concentration of 0.75 mol / dm3. Calculate the concentration of sulfuric acid in g / dm3.  g / dm3 
4. Electrochemistry  →  4.1. Electrolysis
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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6
Ethane, propane and butane are members of the same homologous series. Name this homologous series. State two ways members of the same homologous series are similar.  One mole of ethane, C2H6, contains 6.02×1023 molecules. Calculate how many molecules are in 15 g of ethane.  number of ethane molecules = Propane reacts with chlorine. Write the formula of the product which does not contain carbon. Draw the structure of an organic product formed. Show all of the atoms and all of the bonds.  State the name of this type of reaction. Aqueous bromine was added to a sample of ethene. Give the colour change seen. from to Explain, in terms of bonding, why there is no colour change when aqueous bromine is added to ethane. There are two structural isomers with the formula C4H10. Draw the structures of both of these isomers, showing all of the atoms and all of the bonds.  Butane is formed when longer chain hydrocarbons are cracked. Complete the chemical equation to show the other product when butane is formed by cracking. C6H14 → C4H10 +  A compound contains 85.7% carbon and 14.3% hydrogen by mass. Calculate the empirical formula of this compound. Show your working.  The molecular mass of the compound is 112. Calculate the molecular formula of this compound.  
11. Organic chemistry  →  11.5. Alkenes
11. Organic chemistry  →  11.2. Naming organic compounds
11. Organic chemistry  →  11.1. Formulae, functional groups and terminology
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Ethanol can be manufactured by two different methods. Method 1: fermentation of a sugar, C6H12O6 C6H12O6 → 2C2H5OH + 2CO2 Method 2: reaction of ethene with steam C2H4 + H2O → C2H5OH Give one advantage of using fermentation compared with Method2. Give one disadvantage of using fermentation compared with Method2. Ethanol reacts with acidified potassiummanganate(to form water and a product that turns litmus red. State the name of the product that turns the litmus red. State the type of reaction that ethanol undergoes when it reacts with acidified potassiummanganate(. Ethanol reacts with methanoicacid to form an ester. Name the ester formed in this reaction. Draw the structure of the ester formed. Show all of the atoms and all of the bonds.  The table shows the melting points of ethanol and sodiumchloride. substance melting point / °C ethanol –114 sodium chloride The difference in melting points is due to differences in attractive forces between particles in these substances. Name the type of attractive force in each substance, which is responsible for the difference in melting points. ethanol sodium chloride  
11. Organic chemistry  →  11.6. Alcohols
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