0620_s13_qp_21
A paper of Chemistry, 0620
Questions:
8
Year:
2013
Paper:
2
Variant:
1
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1
For Examiner’s Use The electronic structures of fi ve atoms of different elements, A, B, C, D and E, are shown below. A B C D E Answer the following questions about these structures. Each structure may be used once, more than once or not at all. Which structure is in Period 4 of the Periodic Table, is a noble gas, is in Group II of the Periodic Table, has fi ve electrons in its outer shell, has a proton number of 7, represents a fl uorine atom? Complete the following sentences about elements using words from the list below. alkali atom covalent ion monatomic three transition two An element is a substance containing only one type of . The Group VII elements exist as molecules containing atoms. Carbon has a giant structure with many strong bonds. Elements such as iron and copper, which form coloured compounds, are called elements.
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
For Examiner’s Use The table below shows some properties of the Group I elements. metal density in g / cm3 melting point / °C boiling point / °C lithium 0.53 sodium 0.97 potassium 0.86 rubidium 1.53 caesium 1.88 Use the information in the table to explain why caesium is a liquid when the temperature is 34 °C. Suggest a value for the boiling point of potassium. °C Describe the general trend in density down the group. Which element does not follow this trend? State three physical properties of potassium, other than density, melting point and boiling point. Potassium reacts with water. The products are potassium hydroxide and hydrogen. Describe two observations when potassium reacts with water. Complete the symbol equation for this reaction. 2K + H2O → 2KOH +
8. The Periodic Table  →  8.2. Group I properties
10. Chemistry of the environment  →  10.1. Water
9. Metals  →  9.4. Reactivity series
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3
For Examiner’s Use Match the name of the homologous series on the left with its formula on the right. The fi rst one has been done for you. halogenoalkane alkane alkene alcohol carboxylic acid C2H6 C2H4 C2H5OH C2H5Cl CH3COOH Draw the full structural formula of the compound, C2H6, showing all atoms and bonds. The compound with the formula C2H4 is an unsaturated hydrocarbon. Describe the difference between a saturated and an unsaturated hydrocarbon in terms of the bonds they contain. Describe a test to distinguish between a saturated and unsaturated hydrocarbon. test result with saturated hydrocarbon result with unsaturated hydrocarbon
11. Organic chemistry  →  11.5. Alkenes
11. Organic chemistry  →  11.1. Formulae, functional groups and terminology
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4
For Examiner’s Use Farmers spread fertilisers on the soil where crops are to be grown. Why do farmers use fertilisers? In your answer, include ● the names of the essential elements present in most fertilisers, ● the reasons why farmers use fertilisers. Urea can be used as a fertiliser. The structure of urea is shown below. C O N H H N H H Deduce the molecular formula of urea. Calculate the relative molecular mass of urea. You must show all your working. For Examiner’s Use Urea is a solid at room temperature. Complete the diagram below to show the arrangement of the molecules in solid urea. Show a molecule of urea as When urea is heated with an alkali, ammonia is given off. Describe a test for ammonia. test result
10. Chemistry of the environment  →  10.2. Fertilisers
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
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5
For Examiner’s Use The table shows some properties of four substances, A, B, C and D. substance melting point / °C does the solid conduct electricity? does a solution of the solid conduct electricity? A yes does not dissolve B no dissolves and conducts C no does not dissolve D no does not dissolve Which one of these substances has a giant covalent structure, a simple molecular structure, a metallic structure? A student carried out an experiment to determine the rate of reaction of calcium carbonate with excess hydrochloric acid. CaCO3+ 2HCl → CaCl 2+ CO2+ H2OHe recorded the loss of mass of the reaction mixture over a period of time. 362.05 cotton wool small pieces of calcium carbonate balance hydrochloric acid Explain why the reaction mixture decreases in mass. For Examiner’s Use He carried out the reaction at constant temperature using 2 g of calcium carbonate in small pieces. The hydrochloric acid was in excess. He plotted his results on a grid. This is shown below. 1.0 0.8 0.6 0.4 0.2 time / seconds loss in mass / g At what time has the reaction just fi nished? s From the graph, deduce the loss in mass in the fi rst 100 seconds. g The student repeated the experiment keeping everything the same except for the size of the pieces of calcium carbonate. He used smaller pieces of calcium carbonate but the mass used was the same. On the grid above, draw a line to show how the loss of mass changes with time when smaller pieces of calcium carbonate are used. State the effect of increasing the concentration of hydrochloric acid on the rate of this reaction when all other factors remain constant.
6. Chemical reactions  →  6.2. Rate of reaction
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6
For Examiner’s Use Propanol is a solvent. Sugar is soluble in propanol. Salt (sodium chloride) is insoluble in propanol. A student wants to separate a mixture of solid salt and solid sugar. Describe how she could separate the salt from the sugar. You may draw a labelled diagram to help you answer this question. Describe how the student could obtain solid sodium chloride from a solution of sodium chloride in water. The diagram shows the structure of sodium chloride. Na+ Cl – Na+ Cl – Na+ Na+ Cl – Cl – Na+ Cl – Na+ Cl – Na+ Na+ Cl – Cl – Deduce the simplest formula for sodium chloride. What type of bonding is present in sodium chloride? Put a ring around the correct answer. covalent ionic metallic weak For Examiner’s Use The diagram shows the apparatus used to electrolyse a concentrated aqueous solution of sodium chloride. + – A C D B Which letter on the diagram, A, B, C or D, represents the electrolyte? Name the product formed at the positive electrode, the negative electrode.
7. Acids, bases and salts  →  7.3. Preparation of salts
4. Electrochemistry  →  4.1. Electrolysis
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
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7
For Examiner’s Use A student set up the apparatus shown below. The concentrated hydrochloric acid gives off hydrogen chloride gas. After 15 seconds, the damp blue litmus paper begins to turn red. After 25 seconds, the litmus paper has turned completely red. damp blue litmus paper cotton wool soaked in concentrated hydrochloric acid long glass tube at the start slightly red after 15 seconds all red after 25 seconds Use ideas about moving particles to explain these observations. Hydrogen chloride reacts with ammonia to form a salt which has the formula NH4Cl. State the name of this salt. Hydrochloric acid reacts with iron to form iron(chloride and hydrogen. Write a word equation for this reaction. Describe a test for iron(ions. test result For Examiner’s Use A student investigates various methods of protecting iron from rusting. She sets up four tubes as shown in the diagram below. tube 1 iron nail water iron tube 2 tube 3 tube 4 oil iron water iron completely coated with plastic water iron incompletely coated with plastic Tube 1 contains unprotected iron. What is the purpose of this experiment? State the names of the two substances needed for iron to rust. and Explain why the iron in tube 4 does not rust. Explain why the iron in tube 3 eventually rusts.
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
9. Metals  →  9.4. Reactivity series
9. Metals  →  9.5. Corrosion of metals
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8
For Examiner’s Use The diagram shows a silvered light bulb. thin coil of tungsten wire plastic copper wires brass lamp holder thin layer of silver alloy Some properties of metals used in the light bulb are shown in the table below. metal hardness electrical conductivity melting point / °C price / $ per tonne brass hard good about 1000 7 000 copper fairly soft very good 9 600 silver fairly soft very good 1 300 000 tungsten hard good Suggest why copper rather than tungsten is used for electrical wiring? Suggest why silver is not used for electrical wiring. Suggest two reasons why tungsten rather than copper is used to make the bulb fi lament. reason 1 reason 2 Explain why the copper wires are covered with plastic. For Examiner’s Use Brass is an alloy. Which one of the following diagrams, A, B, C or D, best represents an alloy? A B C D
9. Metals  →  9.2. Uses of metals
9. Metals  →  9.3. Alloys and their properties
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