0620_w11_qp_21
A paper of Chemistry, 0620
Questions:
8
Year:
2011
Paper:
2
Variant:
1
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1
For Examiner’s Use Chromatography can be used to test for the purity of substances. Describe one area in everyday life where purity of substances is important. Mineral water contains dissolved salts such as magnesium chloride. Which one of the following statements about mineral water is correct? Tick one box. Mineral water boils at slightly above 100 °C. Mineral water is pure water. Mineral water boils at exactly 100 °C. Another name for mineral water is fi zzy water. The diagram shows the apparatus used to separate different dyes in food colourings. spot of food colouring placed here Label the diagram in the boxes provided using the words below. chromatography paper origin line solvent solvent front For Examiner’s Use The diagram below shows the chromatography of four different food colourings, A, B, C and D. A B C D at the start of the experiment A B C D the final chromatogram Which food colouring, A, B, C or D, contains only one dye? Which three food colourings have one dye in common? Which food colouring contains the greatest number of dyes?
12. Experimental techniques and chemical analysis  →  12.3. Chromatography
10. Chemistry of the environment  →  10.1. Water
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2
For Examiner’s Use A student set up an experiment to demonstrate rusting as shown below. He made observations at the start of the experiment, after 2 weeks and after 4 weeks. measuring cylinder air water 10 cm3 8 cm3 iron wool 8 cm3 start after 2 weeks after 4 weeks What conditions are needed for the iron wool to rust? Two weeks after the start of the experiment, the volume of air in the measuring cylinder had decreased. After a further two weeks there was no change in the volume of air. Explain the results of this experiment. What change would you observe in the iron wool as it rusted? appearance at start appearance after 2 weeks Rust contains iron(ions. Describe a test for iron(ions. test result For Examiner’s Use Clean iron reacts with dilute hydrochloric acid. Fe + 2HCl → FeCl 2 + H2 Write a word equation for this reaction.
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
9. Metals  →  9.5. Corrosion of metals
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3
For Examiner’s Use The diagram shows some of the elements in Period 3 of the Periodic Table. Na Mg Si P S Cl Ar From the diagram, choose one element which forms a basic oxide. two elements which form acidic oxides. and Describe how metallic character of the elements changes across a period. What determines the order of the elements in the Periodic Table? The missing element in the table is aluminium. Describe the structure of an aluminium atom. In your description write about ● the number and types of particles in the nucleus ● the electrons. For Examiner’s Use Use the information in the table below to explain why aluminium is used in preference to iron or titanium for overhead electricity cables. Give two reasons. metal electrical conductivity density in g / cm3 melting point / °C strength price in £ / kg aluminium very good 2.7 fairly strong iron good 7.9 strong titanium good 4.5 very strong Chlorine is a green gas. When chlorine is bubbled through an aqueous solution of potassium bromide, the solution turns orange. Complete the symbol equation for this reaction. Cl 2 + KBr → + KCl Argon is a noble gas which is denser than air. Which one of these statements about argon is correct? Tick one box. Argon reacts rapidly with chlorine. Argon is used for fi lling balloons. Argon has a complete outer shell of valency electrons. Argon has only two valency electrons in its outer shell.
9. Metals  →  9.2. Uses of metals
9. Metals  →  9.4. Reactivity series
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4
For Examiner’s Use Ethane is a saturated hydrocarbon. Ethene is an unsaturated hydrocarbon. Describe how you can distinguish between ethane and ethene using aqueous bromine. The diagram shows the apparatus used to crack long chain alkanes into alkenes and shorter chained alkanes in the laboratory. long chain alkane absorbed into mineral wool hot aluminium oxide water alkene State two conditions needed for cracking. What information in the diagram shows that alkenes are insoluble in water? Propene is an alkene. The formula of propene is C3H6. Calculate the relative molecular mass of propene. Complete the equation for the cracking of the alkane tetradecane, C14H30. C14H30 → + C10H22 For Examiner’s Use Polyis formed from ethene monomers. Select two words from the list that describe this reaction. addition condensation dehydration fermentation neutralisation polymerisation and
11. Organic chemistry  →  11.5. Alkenes
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5
For Examiner’s Use A pupil studied the effect of temperature on the speed of reaction of aqueous sodium thiosulfate with dilute hydrochloric acid. When he added hydrochloric acid to a solution of sodium thiosulfate, a precipitate of sulfur gradually formed. He recorded the time taken for some writing placed under the fl ask to disappear from view. experiment experiment sodium thiosulfate solution precipitate of sulfur add hydrochloric acid He repeated the experiment at different temperatures. The table shows his results. temperature / °C time taken for the writing to disappear from view / s For Examiner’s Use On the grid below, plot a graph of the time taken against temperature. temperature / °C time taken / s At which temperature was the reaction the fastest? Describe how the temperature affects the speed of reaction. Suggest how the speed of this reaction at 30 °C will change when the concentration of hydrochloric acid is increased. For Examiner’s Use The equation for the reaction is Na2S2O3+ 2HCl → 2NaCl + SO2+ S+ H2OState the name of the salt formed in this reaction. To which group in the Periodic Table does sulfur belong? Sulfur dioxide is formed when coal is burnt in power stations. State one harmful effect of sulfur dioxide on the environment. Sulfur dioxide can be removed in power stations by fl ue gas desulfurisation. Which one of these compounds is used to remove the sulfur dioxide in this process? Tick one box. calcium chloride calcium oxide nitrogen dioxide potassium nitrate Magnesium burns in sulfur dioxide. 2Mg + SO2 → 2MgO + S Refer to this equation to explain why this is a redox reaction.
6. Chemical reactions  →  6.2. Rate of reaction
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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6
For Examiner’s Use The diagram shows the fl ame from a Bunsen burner when its air hole is open. outer zone middle zone inner cone In the outer zone of the fl ame, methane undergoes complete combustion. Complete the equation for the complete combustion of methane. CH4 + → CO2 + 2H2O In the middle zone of the fl ame, less air is present and incomplete combustion occurs. State the name of the poisonous gas formed during the incomplete combustion of methane. The inner cone of the fl ame contains only unburnt methane. A student put a match in the Bunsen burner as shown in the diagram below. He then lit the Bunsen burner. match head pin Suggest why the match did not catch fi re. For Examiner’s Use The products of the complete combustion of methane were drawn through the apparatus shown below. A B to suction pump anhydrous copper sulfate soda lime granules State the name of the substance that turned the white copper sulfate in tube A, blue. How could you change blue copper sulfate to white copper sulfate? The soda lime in tube B absorbs carbon dioxide. State and explain what happens to the mass of the soda lime as the experiment proceeds. Methane is a greenhouse gas. State one source of the methane in the atmosphere. State one effect of an increased concentration of methane in the atmosphere.
10. Chemistry of the environment  →  10.3. Air quality and climate
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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7
For Examiner’s Use A student studied the reaction of citric acid with sodium hydrogen carbonate. She put a solution of citric acid in a plastic cup and measured its temperature. She then added sodium hydrogen carbonate powder and measured the temperature again. thermometer plastic cup sodium hydrogen carbonate citric acid solution lid The temperature of the reaction mixture decreased. Which one of these statements about this reaction is correct? Tick one box. The reaction released heat energy. The reaction is exothermic. The reaction is endothermic. The products have less energy than the reactants. The structure of citric acid is shown below. COOH CH2 C COOH HO CH2 COOH On this structure, put a ring around the alcohol functional group. Write the simplest formula for citric acid. For Examiner’s Use Salts of citric acid can be prepared from lemon juice. The lemon juice is fi rst boiled to remove various substances including enzymes. What do you understand by the term enzyme? The lemon juice is then neutralised with calcium carbonate and solid calcium citrate is formed. Suggest how the calcium citrate can be separated from the mixture. Carbon dioxide gas is released when citric acid solution reacts with calcium carbonate. Describe a test for carbon dioxide. test result The concentration of a citric acid solution can be found by carrying out a titration using the apparatus shown below. sodium hydroxide solution citric acid solution Describe how to carry out this titration.
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
11. Organic chemistry  →  11.7. Carboxylic acids
9. Metals  →  9.4. Reactivity series
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8
For Examiner’s Use The diagram shows an electrolysis cell for extracting sodium from molten sodium chloride. – – + – + B C D A sodium E molten sodium chloride sodium power supply Which letter on the diagram represents the electrolyte? the cathode? Which one of the following substances is most likely to be used as the anode? Put a ring around the correct answer. graphite sodium sulfur zinc What information from the diagram suggests that sodium is less dense than molten sodium chloride? Predict the product formed at the anode during this electrolysis. Name the gases formed at the anode and cathode when an aqueous solution of sodium chloride is electrolysed. product at the anode product at the cathode
4. Electrochemistry  →  4.1. Electrolysis
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