0620_s15_qp_22
A paper of Chemistry, 0620
Questions:
7
Year:
2015
Paper:
2
Variant:
2
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1
The structures of six compounds containing oxygen are shown below. O2− Ca2+ O2− Ca2+ Ca2+ O2− Ca2+ O2− O2− Ca2+ O2− Ca2+ NO3 − NH4 + NH4 + NH4 + NH4 + NO3 − NH4 + NO3 − NO3 − NO3 − NO3 − NH4 + A E F B C D O C O Xe O O O O H O H O O S O O O O Si Si Si Si Si O O O O Si Si O O Si Si O O Answer the following questions about these compounds. Each compound, A, B, C, D, E or F, may be used once, more than once or not at all. Which compound is a compound of a noble gas? Which compound can be used as a fertiliser? Which compound can be used to neutralise acidic soil? Which compound is a greenhouse gas? Which two compounds are ionic? and Which two compounds react to form calcium sulfate? and Complete the symbol equation for the reaction of compound A with hydrochloric acid. CaO + HCl CaCl2 + Complete the following sentence about compounds using words from the list below. atoms combined mixtures molecules separated unreactive A compound is a substance containing two or more different which are chemically .
11. Organic chemistry  →  11.2. Naming organic compounds
3. Stoichiometry  →  3.1. Formulae
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2
An aqueous solution of sodium hydrogen carbonate is added to an aqueous solution of citric acid. The mixture is stirred. The temperature is measured before and after the addition. citric acid sodium hydrogen carbonate 20 °C 11 °C 20 °C Explain how this experiment shows that the reaction is endothermic. Citric acid reacts with sodium hydroxide to form the soluble salt sodium citrate. Describe how you could prepare pure dry crystals of sodium citrate from citric acid and sodium hydroxide. Citric acid can be made by fermentation. Ethanol can also be made by fermentation. Which of the following are required to make ethanol by fermentation? Tick two boxes. enzymes from yeast temperature above 100 °C high pressure concentrated sulfuric acid glucose Complete the structure of ethanol to show all atoms and all bonds. O H Ethanol can be made from ethene. Complete the following sentence about the formation of ethanol from ethene using words from the list below. carbonate catalyst hydrogen proton steam Ethanol can be made by reacting ethene with in the presence of a .
11. Organic chemistry  →  11.6. Alcohols
11. Organic chemistry  →  11.7. Carboxylic acids
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3
When sodium hydrogen carbonate is heated at 60 °C, carbon dioxide is given off. Complete the equation for this reaction. NaHCO3 Na2CO3 + CO2 + What type of chemical reaction is this? Tick one box. addition neutralisation oxidation thermal decomposition An aqueous solution of sodium hydrogen carbonate is slightly alkaline. Which one of the following pH values is slightly alkaline? Put a ring around the correct answer. pH 2 pH 7 pH 8 pH 13 Baking powder contains sodium hydrogen carbonate and crystals of a weak acid. When water is added, the acid reacts with the sodium hydrogen carbonate. Complete the general equation for the reaction of an acid with a carbonate. acid + carbonate carbon dioxide + + The diagram below shows bread baked with and without the addition of baking powder. All other conditions were kept the same. bread baked without baking powder bread baked with baking powder Why is the bread baked with baking powder bigger? Explain why the sodium hydrogen carbonate used in breadmaking must be pure. The diagram shows the arrangement of carbon dioxide molecules at –25 °C and 100 atmospheres pressure. represents a molecule of carbon dioxide What is the state of carbon dioxide under these conditions? Use the kinetic particle theory and the information in the diagram to explain your answer.
9. Metals  →  9.4. Reactivity series
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
11. Organic chemistry  →  11.5. Alkenes
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4
A student investigated the rate of reaction of zinc with dilute hydrochloric acid. Zn+ 2HClZnCl2+ H2Complete the labelling of the apparatus by filling in the two boxes. dilute hydrochloric acid zinc thermometer water bath at 20 °C The student carried out the reaction at 20 °C using small pieces of zinc. She measured the volume of hydrogen given off as the reaction proceeded. time / min volume of hydrogen / cm3 Describe how the volume of hydrogen changes with time. At what time did the reaction stop? What volume of gas was produced over the first two minutes of the reaction? On the graph above draw a line to show how the volume of hydrogen changes when the reaction was carried out at 30 °C. All other conditions remain the same. How does the rate of reaction change when larger pieces of zinc are used? All other conditions remain the same. Molten zinc chloride can be electrolysed using graphite electrodes. State the names of the product formed at: the anode the cathode. Graphite conducts electricity. Give one other reason why graphite electrodes are used.
4. Electrochemistry  →  4.1. Electrolysis
6. Chemical reactions  →  6.2. Rate of reaction
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5
Cinnamic acid is found in plants called balsams. The structure of cinnamic acid is shown below. C C C C H C C H H H H C H C H C O O H On the structure of cinnamic acid above, put a ring around the carboxylic acid functional group. Cinnamic acid is an unsaturated compound. What is the meaning of the term unsaturated ? Describe a test for an unsaturated compound. Cinnamic acid reacts with sodium hydroxide to form styrene. C6H5CH=CHCOOH + 2NaOH C6H5CH=CH2 + Na2CO3 + H2O Complete the word equation for this reaction. cinnamic sodium + styrene + + acid hydroxide Styrene is used to make the polymer poly. Polyis also a polymer. Describe how polyis made. In your answer include the words: • addition • ethene • monomer • polymerisation Balsam flowers contain a mixture of pigments. Describe how you could obtain a solution of this mixture of pigments from balsam flowers. A student uses chromatography to separate the pigments in balsam flowers. He puts the pigment mixture on a sheet of chromatography paper as well as 5 spots of pure pigments A, B, C, D and E. The diagram below shows the results after chromatography. pigments from balsam flowers A B C D E Which of the pigments A, B, C, D and E are present in balsam flowers?
11. Organic chemistry  →  11.7. Carboxylic acids
11. Organic chemistry  →  11.8. Polymers
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6
The table shows some properties of aluminium, copper, iron and sodium. metal electrical conductivity density in g / cm3 melting point / °C strength colour aluminium very good 2.70 fairly strong silver copper very good 8.92 very strong pink-brown iron good 7.86 very strong silver sodium good 0.97 weak silver Which two metals in the table are transition elements? Explain your answer by referring to a specific property of transition elements given in the table. Use the information in the table to suggest why overhead electricity cables are made from aluminium with a steel core, one reason why sodium is not used for electricity cables. Cobalt chloride is a transition element compound. Calcium chloride is a compound of a Group II metal. Describe one difference between cobalt chloride and calcium chloride. The table below shows some observations about the reaction of four metals with water or steam. metal observations aluminium reacts with steam when strongly heated lithium reacts rapidly with cold water magnesium reacts very slowly with cold water but rapidly with steam silver does not react with steam Place these metals in order of their reactivity. least reactive most reactive When iron is heated with steam, hydrogen is given off. 3Fe + 4H2O Fe3O4 + 4H2 What does the sign mean? Describe a test for hydrogen. test result Steel is an alloy of iron. Write about alloys of iron. In your answer refer to: • the meaning of the term alloy, • why alloys are used instead of pure iron, • an example of the use of an alloy of iron.
9. Metals  →  9.4. Reactivity series
9. Metals  →  9.2. Uses of metals
9. Metals  →  9.1. Properties of metals
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7
A teacher placed a few drops of liquid bromine in the bottom of a test-tube containing a solvent. After 10 minutes, the brown colour of the bromine had spread a little way through the solvent. After 2 hours, the brown colour had spread throughout the solvent. at the start after 10 minutes after 2 hours solvent liquid bromine Use the kinetic particle theory to explain these observations. Bromine is a halogen in Group VII. The properties of some halogens are given in the table below. halogen melting point / °C boiling point / °C density at boiling point in g / cm3 electron arrangement of halogen atom fluorine –220 –188 1.51 2,7 chlorine –101 –35 1.56 2,8,7 bromine –7 +59 2,8,18,7 iodine +114 +184 4.93 2,8,18,18,7 Use the information in the table to: Deduce the state of fluorine at –200 °C. Describe how the melting point changes down Group VII. Estimate the density of bromine. Deduce the number of completely filled electron shells in an atom of chlorine. Aqueous bromine reacts with aqueous potassium iodide to form iodine and potassium bromide. Complete the equation for this reaction. Br2 + 2KI + 2KBr Explain why aqueous bromine does not react with an aqueous solution of potassium chloride. Bromine reacts with fluorine to form bromine trifluoride, BrF3. Calculate the relative molecular mass of bromine trifluoride. Show all your working.
11. Organic chemistry  →  11.5. Alkenes
8. The Periodic Table  →  8.3. Group VII properties
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