0620_s05_qp_2
A paper of Chemistry, 0620
Questions:
6
Year:
2005
Paper:
2
Variant:
0
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1
Use The structures of some substances are shown below. Br H C H C H H C H H H C H H H H I– Na+ I– Na+ Na+ I– I– I– Na+ Na+ I– Na+ I– Na+ Na+ I– I– I– Na+ Na+ C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C A B D E C Answer these questions using the letters A, B, C, D or E. Which structure is methane? Which two structures are giant structures? and Which two structures are hydrocarbons? and Which structure contains ions? Which two structures have very high melting points? and Examiner's Use Structure E is a form of carbon. What is the name of this structure? Put a ring around the correct answer. carbide graphite lead poly Name another form of carbon. Write the simplest formula for substance B. Is substance D an element or a compound? Explain your answer.
2. Atoms, elements and compounds  →  2.5. Simple molecules and covalent bonds
1. States of matter  →  1.1. Solids, liquids and gases
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2
Use A student collected some water from a polluted river. The water contained soluble solids and insoluble clay and had a pH of 5. How can the student separate the clay from the rest of the river water? The student uses litmus paper to show that the river water is acidic. What will be the result of this test? The student then boiled the river water to obtain the soluble solids. The diagram shows how she heated the water. steel can copper gauze iron tripod boiling water natural gas steam Which of the substances named in the diagram is an alloy, a compound which is liquid at room temperature, an element, a fuel? Name the main substance in natural gas. What is the normal temperature of boiling water? Examiner's Use After the student boiled off the water, she analysed the white powder on the inside of the steel can. The table shows her results. name of ion formula of ion mass of ion present /milligrams calcium Ca2+ carbonate CO3 2– chloride Cl – nitrate NO3 – sodium Na+ sulphate SO4 2– Which positive ion had the greatest concentration in the sample of river water? Complete the following equation to show how a sodium ion is formed from a sodium atom. Na Na+ + Instead of using natural gas, the student could have used butane to heat the water. The formula of butane is C4H10. What products are formed when butane burns in excess air? Name the poisonous gas formed when butane undergoes incomplete combustion.
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
9. Metals  →  9.4. Reactivity series
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3
Use Ammonia is a gas which forms an alkaline solution when dissolved in water. Complete the diagram below to show the arrangement of the molecules in ammonia gas. O represents a single molecule of ammonia. O Which one of the following values is most likely to represent the pH of a dilute solution of ammonia? Put a ring around the correct answer. pH2 pH6 pH7 pH9 The structure of the ammonia molecule is shown below. N H H H Write the simplest formula for ammonia. Describe the type of bonding in a molecule of ammonia. Ammonia is a gas at room temperature. Suggest why ammonia has a low boiling point. Examiner's Use Many fertilisers contain ammonium sulphate. Which acid must be added to ammonia solution to make ammonium sulphate? Put a ring around the correct answer. HCl HNO3 H3PO4 H2SO4 Fill in the missing words in the following sentence using two of the words from the list. air hydrogen nitrogen soil sodium water Fertilisers are needed in agriculture to replace the , phosphorus and other elements which are removed from the when crops are grown. A solution of ammonia has a strong smell. A beaker of ammonia solution is put in the corner of a room which is free of draughts. beaker of ammonia solution girl (standing by window) At first, the girl by the closed window cannot smell the ammonia. After 30 seconds she smells the ammonia. Use the kinetic particle theory to explain these facts. Examiner's Use The diagram shows the apparatus used for oxidising ammonia in the laboratory. air tongs platinum wire ammonia solution First, nitrogen(oxide, NO, is produced. This then reacts with oxygen to form nitrogen(oxide, NO2. Where does the oxygen come from in this reaction? Balance the equation for the reaction of nitrogen(oxide with oxygen. 2NO + O2 NO2 What is the meaning of the symbol ? The platinum wire acts as a catalyst in the reaction. As the reaction takes place, the wire begins to glow red hot. What does this show about the reaction?
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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4
Use Polyis a plastic which is made by polymerizing ethene, C2H4. Which one of the following best describes the ethene molecules in this reaction? Put a ring around the correct answer. alcohols alkanes monomers polymers products The structure of ethane is shown below. C H H C H H H H Explain, by referring to its bonding, why ethane cannot be polymerized. Draw the structure of ethene, showing all atoms and bonds. Ethene is obtained by cracking alkanes. Explain the meaning of the term cracking. What condition is needed to crack alkanes? Complete the equation for cracking decane, C10H22. C10H22 C2H4 + Examiner's Use Some oil companies ‘crack’ the ethane produced when petroleum is distilled. Complete the equation for this reaction. C2H6 C2H4 + Describe the process of fractional distillation which is used to separate the different fractions in petroleum. State a use for the following petroleum fractions. petrol fraction lubricating fraction
11. Organic chemistry  →  11.3. Fuels
11. Organic chemistry  →  11.8. Polymers
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5
Use The halogens are a group of diatomic non-metals showing a trend in colour, state and reactivity. In this description, what is the meaning of diatomic, state? The table gives some information about some of the halogens. element melting point / oC boiling point / oC colour state at room temperature chlorine -101 -35 green bromine -7 +59 iodine +114 grey-black Complete the last column in the table to show the state of each of the halogens at room temperature. State the colour of bromine. Suggest a value for the boiling point of iodine. Complete the word equation for the reaction of chlorine with potassium iodide. chlorine + potassium iodide + Examiner's Use Draw a diagram to show the electronic structure of a chlorine molecule. Show only the outer electrons. State a use of chlorine. The structures of some substances containing halogens are shown below. Cl H Br Br Br F F F Cl – Na+ Na+ Cl – Na+ Cl – Na+ Cl – Na+ Cl – Cl – Na+ A B C D Which one of these structures, A, B, C or D, shows an element? Which one of these structures forms hydrochloric acid when dissolved in water? Complete the following sentence. Structure B conducts electricity when it is molten because Examiner's Use Astatine, At, is below iodine in Group VII of the Periodic Table. In which Period of the Periodic Table is astatine? How many protons does astatine have in its nucleus? Astatine has many isotopes. What do you understand by the term isotopes? The most common isotope of astatine has a nucleon number (mass number) of 210. Calculate the number of neutrons in this isotope of astatine.
8. The Periodic Table  →  8.3. Group VII properties
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6
Use The electroplating of iron with chromium involves four stages. 1. The iron object is cleaned with sulphuric acid, then washed with water. 2. The iron is plated with copper. 3. It is then plated with nickel to prevent corrosion. 4. It is then plated with chromium. The equation for stage 1 is Fe + H2SO4 FeSO4 + H2 Write a word equation for this reaction. Describe a test for the gas given off in this reaction. test result The diagram shows how iron is electroplated with copper. + _ rod of pure copper iron object copper(sulphate solution Choose a word from the list below which describes the iron object. Put a ring around the correct answer. anion anode cathode cation What is the purpose of the copper(sulphate solution? Every reasonable effort has been made to trace all copyright holders where the publishers (i.e. UCLES) are aware that third-party material has been reproduced. The publishers would be pleased to hear from anyone whose rights they have unwittingly infringed. University of Cambridge International Examinations is part of the University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. Examiner's Use Describe what happens during the electroplating to the iron object, the rod of pure copper. Describe a test for copper(ions. test result Suggest why chromium is used to electroplate articles. The information below shows the reactivity of chromium, copper and iron with warm hydrochloric acid. chromium – few bubbles of gas produced every second copper – no bubbles of gas produced iron – many bubbles of gas produced every second Put these three metals in order of their reactivity with hydrochloric acid. Most reactive → Least reactive →
4. Electrochemistry  →  4.1. Electrolysis
9. Metals  →  9.4. Reactivity series
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