0620_s14_qp_21
A paper of Chemistry, 0620
Questions:
7
Year:
2014
Paper:
2
Variant:
1
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2
In 1904, J. J. Thomson suggested a model of the atom. He called this the ‘plum pudding’ model. This model of an atom, containing 14 electrons, is shown below. sphere of positive charge which is spread out electrons Describe how Thomson’s model of the atom differs from our present ideas of the structure of an atom. Lithium has two naturally-occurring isotopes. These can be written as: 3Li 3Li and Describe the difference between these isotopes. Isotopes can be radioactive or non-radioactive. State one industrial use of radioactive isotopes. Lithium is in Group I of the Periodic Table. The table shows some properties of the Group I elements. metal melting point / °C atomic radius / nm lithium 0.157 sodium 0.191 potassium rubidium 0.250 caesium 0.272 Deduce: the melting point of lithium, °C the atomic radius of potassium nm Lithium reacts with water. An alkaline solution and a colourless gas are formed. Complete the word equation for this reaction. lithium + water → + What is the most likely pH of the alkaline solution? Put a ring around the correct answer. pH 2 pH 5 pH 7 pH 13 Draw the electronic structure of a potassium atom.
2. Atoms, elements and compounds  →  2.2. Atomic structure and the Periodic Table
8. The Periodic Table  →  8.1. Arrangement of elements
8. The Periodic Table  →  8.2. Group I properties
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The table shows some fractions obtained from the distillation of petroleum. fraction number of carbon atoms boiling point of the fraction / °C refi nery gas 1 – 4 under 40 gasoline 5 – 10 40 – 160 kerosene 10 – 16 160 – 250 diesel 16 – 20 250 – 300 fuel oil 20 – 30 300 – 350 What is the relationship between the number of carbon atoms and the boiling points of the fractions? State the names of two petroleum fractions not given in the table. and Two of the compounds present in refi nery gas are methane and ethane. Draw the structure of ethane. Show all atoms and bonds. Complete the dot and cross diagram of methane to show all the electrons. H H H C H Refi nery gas also contains propane. Propane can be cracked in the presence of a catalyst to form hydrogen. Complete the symbol equation for this reaction. C3H8 → + H2 A catalyst is one condition needed to crack an alkane. State one other condition needed to crack an alkane.
11. Organic chemistry  →  11.3. Fuels
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The diagram shows the changes of state when tin vapour is cooled slowly to room temperature. tin vapour liquid tin solid tin condensation solidification Explain what happens to the arrangement and motion of the atoms during these changes. Tin is a metal in Group IV of the Periodic Table. How many electrons does tin have in its outer shell? State one physical property of tin. The table below describes the reaction of some metals with dilute hydrochloric acid. iron bubbles of gas produced and temperature of the mixture rises slowly magnesium many bubbles of gas produced rapidly and temperature of the mixture rises rapidly silver no bubbles of gas given off and no temperature change tin a few bubbles of gas given off slowly and temperature of the mixture rises very slowly Put these metals in order of their reactivity. least reactive most reactive Tin is extracted by heating tin(oxide with carbon. Complete the symbol equation for this reaction. SnO2 + C → Sn + CO State one adverse effect of carbon monoxide on health.
9. Metals  →  9.4. Reactivity series
1. States of matter  →  1.1. Solids, liquids and gases
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The diagram shows a blast furnace for extracting iron. mixture of iron ore and coke On the diagram above, write: ● the letter A to show where the air blast enters the furnace, ● the letter W to show where the waste gases exit the furnace. Which one of the following is an ore of iron? Put a ring around the correct answer. calcite fl uorite hematite halite In the furnace, the coke burns to form carbon dioxide. This reaction is exothermic. What is meant by the term exothermic ? Describe a test for carbon dioxide. test result In the blast furnace, carbon dioxide reacts with more coke to form carbon monoxide. The carbon monoxide reduces iron(oxide to iron. Fe2O3 + 3CO → 2Fe + 3CO2 How does this equation show that iron(oxide is being reduced?
9. Metals  →  9.6. Extraction of metals
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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The structure of ethanol is shown below. H C C H H O H H H On the structure above, put a ring around the alcohol functional group. Ethanol can be made by fermentation. Complete the word equation for fermentation. → ethanol + What type of catalysts are used in fermentation? Put a ring around the correct answer. acids carbonates enzymes metals Ethanol can also be made by hydration. Complete the symbol equation for this reaction. + H2O → C2H5OH The diagram below shows how the rate of fermentation changes with temperature. temperature / °C rate Describe how the rate of fermentation changes with temperature. The table shows some properties of different alcohols. alcohol formula melting point / °C boiling point / °C density in g / cm3 methanol CH4O – 94 ethanol C2H6O –117 0.789 propanol C3H8O –126 0.804 butanol C4H10O – 89 0.810 pentanol C5H12O – 79 0.815 Describe how density changes with the number of carbon atoms in the alcohol. Which one of these alcohols has the lowest melting point? Is pentanol a solid, liquid or gas at room temperature? Explain your answer.
11. Organic chemistry  →  11.6. Alcohols
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7
A student used chromatography to separate the dyes in the blue ink from a ball-point pen. She used the equipment shown in the diagrams below. solvent large watchglass chromatography tank chromatography paper Complete the diagram below to show how she set up the apparatus. Describe how chromatography could be used by the student to separate the dyes. The student used water as a solvent. Suggest a different solvent that she could use. The diagram below shows the results of the chromatography using the blue ink, B, and several pure dyes, W, X, Y and Z. B W X Y Z Which of the dyes, W, X, Y and Z, were in the blue ink? How many dyes in the ink had been separated by this chromatography? The diagram shows the ball-point pen used in the experiment. alloy tip polycap ink The cap of the pen is made of poly. Describe the formation of polyfrom ethene. In your answer, include the words: ● monomer, ● polymer. The tip of the pen is made from an alloy. What is meant by the term alloy ? The table shows some properties of four alloys. alloy strength / GPa density in g / cm3 thermal conductivity in W / m / K low strength steel 7.70 high strength steel 7.90 low strength aluminium 2.72 high strength aluminium 2.80 How does the strength of the steel and aluminium alloys vary with their thermal conductivity? Which one of these alloys is the best one to use to make the body of an aircraft? Give two reasons for your answer.
12. Experimental techniques and chemical analysis  →  12.3. Chromatography
9. Metals  →  9.3. Alloys and their properties
9. Metals  →  9.2. Uses of metals
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Zinc can be extracted from zinc sulfi de ore in three steps. In the fi rst step, zinc sulfi de is heated in air to produce zinc oxide. Complete the symbol equation for this reaction. 2ZnS + O2 → 2ZnO + SO2 The product sulfur dioxide, SO2, is harmful to the environment. Explain why it is harmful to the environment and state one effect it has on buildings. In the second step, zinc oxide reacts with sulfuric acid to form zinc sulfate. zinc oxide + sulfuric acid → zinc sulfate + water Zinc sulfate is soluble in water. Some insoluble impurities in the zinc oxide do not react with the sulfuric acid. Suggest how these insoluble impurities are removed from the zinc sulfate solution. In the third step, zinc is extracted from zinc sulfate by electrolysis using the cell shown below. + – lead rod aluminium rod aqueous zinc sulfate Which word best describes the aluminium rod? Put a ring around the correct answer. anion anode cathode cation electrolyte product Suggest which statement about this electrolysis is completely correct. Tick one box. Zinc is formed at the positive electrode and hydrogen at the negative electrode. Zinc is formed at the positive electrode and oxygen at the negative electrode. Zinc is formed at the negative electrode and hydrogen at the positive electrode. Zinc is formed at the negative electrode and oxygen at the positive electrode.
4. Electrochemistry  →  4.1. Electrolysis
9. Metals  →  9.5. Corrosion of metals
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