GCSE Chemistry

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ghoran
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158592
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GCSE Chemistry
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2012-06-13 16:20:43
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  1. Limestone is a hard rock that is used as a building material . Limestone was used by the Egyptians to make plaster
    Reaction 1 - Calcium carbonate , CaCO3 , was decomposed by heating limestone
    CaCO3 ===> CaO + CO2
    Reaction 2 - water was added to the solid produced to make calcium hydroxide
    CaO + H2O ===> Ca(OH)2
    Reaction 3 - a mixture of calcium hydroxide and water was used as plaster . After the plaster had set it became even harder with age
    Ca(OH)2 + CO2 ===> CaCO3 + H2O
    Name the solid formed when calcium carbonate decomposed
    calcium oxide
  2. Limestone is a hard rock that is used as a building material . Limestone was used by the Egyptians to make plaster
    Reaction 1 - Calcium carbonate , CaCO3 , was decomposed by heating limestone
    CaCO3 ===> CaO + CO2
    Reaction 2 - water was added to the solid produced to make calcium hydroxide
    CaO + H2O ===> Ca(OH)2
    Reaction 3 - a mixture of calcium hydroxide and water was used as plaster . After the plaster had set it became even harder with age
    Ca(OH)2 + CO2 ===> CaCO3 + H2O
    use the reactions to explain how the plaster became even harder with age (3)
    Carbon dioxide reacts with the calcium hydroxide , limestone forms and water is lost due to evapouration
  3. A limestone quarry is in an area of natural beauty and near several villages . The company operating the quarry wants planning permission to build a new cemeny works in the quarry . The diagram shows some of the substances used and produced at cement works
    tthe company wants the new cement works because the nearest cement works is 100km from the quarry . The company argues that a new cement works sited inside the quarry would reduce carbon dioxide emmsions . Suggest why the new cement works might reduce carbon dioxide emmisions
    • any one from:
    • • less / no transport
    • •less / no (fossil) fuel used
  4. A limestone quarry is in an area of natural beauty and near several villages . The company operating the quarry wants planning permission to build a new cemeny works in the quarry . The diagram shows some of the substances used and produced at cement works .
    Residents from the villages near the quarry are concerned that there will be atmopsheric pollution from the cement works . Name and explain how emmisions from the chimmney causes atmospheric pollution and what the company should do to reduce this atmopsheric pollution
    • carbon dioxide causes global warming
    • to reduce this pollution they could capture the gas and store it under the sea bed in oils fields
  5. give one piece of evidence that led to Wenger's idea being accepted
    • any one from:
    • • sea floor spreading/ocenaic ridges
    • • periodic measurements between continents
    • • evidence from rocks / fossils on different continents
    • • new mountain ranges
  6. Margerine is manufactured using "hard" plant oils . A margerine company tested several plant oils to deterimine their hardness for use in its margerine . In the test iodine solution was used to find the iodine value . The units are grams of iodine that react with 100g of oil . Plant oils with lower iodine values are harder and are less unsaturated
    The company stated that some of the plant oils were brown and that this may have affected the results . Explain why the company considered the colour of the plant oils to be a problem with this test
    the iodine turns colourless this would be difficult to see if the oil was dark coloured
  7. Copper was considered to be the most suitable material to use for hot water pipes . PEX is now used as an alternative material for hot water pipes . Copper is extracted from its ore by a series of processes .
    * The low grade ore is powdered and concentrated
    * smelting is carried out in an oxygen flash furnace . This furnace is heated 1100°C using a hydrocarbon fuel . The copper ore is blown into the furnace with air , producing impure , molten copper .
    * Oxygen is blown into ther impure , molten copper to remove any sulphur . the copper is cast into rectangular slabs
    * the final purification of copper is done by electrolysis
    PEX is made by a series of processes
    * Fractional distilation
    * cracking
    * polymeristation
    * conversion of poly(ethene) into PEX
    suggest the possibel environmental advntages of using PEX instead of copper for hot water pipes (4)
    • any four from:
    • • less (hydrocarbon) fuels used
    • • less / no electrical energy used
    • • reduce carbon / carbon dioxide emissions
    • • reduce / no pollution bysulfur dioxide / acid rain
    • • continuous process
    • • conserve copper which is runningout or only low-grade ore savailable
    • • reduce the amount of solid waste rock that needs to be disposed
    • • reduce the need to dig large holes(to extract copper ores) (allow less mining)
  8. In recent years we have become more aware of the need to recycle glass used glass bottles can be recycled if they are put into bottle bankssuggest one reason why light bulbs should not be put into bottle banks (1)
    • any one from:
    • • contain metals / filaments / wires
    • • contain other / toxic chemicals /materials
    • • different type of glass
  9. very few glass bottles are reused
    suggest one reason why (1)
    • any one from:
    • • (glass bottles are) recycled
    • • need to be more expensive glassor strong / thicker / different glass (to be reused)
    • • damaged / weaker (with reuse)
    • • need to be cleaned / transported
    • • different sizes / shapes / colours
    • • no refunds paid
  10. new glass bottles cane be also produced by heating , at 1700°C , a mixture of the following raw materials
    sand (silicon dioxide)
    soda ash (sodium carbonate)
    limestone (calcium carbonate)
    explain why the use of recycled glass to make glass bottles uses less carbon dioixde than making glass bottles from raw materials (2)
    • any two from:
    • • low / less energy / heat or lower temperature needed
    • • low / less fuel burned
    • • no (carbon dioxide) fromcarbonate(s)
  11. the bar chart shows the percentages of glass bottles produced and the percentages of glass bottles put into bottle banks in the UK
    tMore green glass bottles are put into bottle banks than are made in the UK . Suggest one reason why . (1)
    • any one from:
    • • (more) imported (as wine bottles)
    • • not much green glass made in theUK
    • • not a high demand (for green glass)
  12. suggest and explain one result from the percentage of clear glass produced in the UK (2)
    Suggest and explain one problem resulting from the percentaege of clear glass bottles produced in the UK (2)
    • any two from:
    • • more (clear) glass is produced (64%) than recycled (40%)
    • • (clear) glass going to landfill
    • • (more) raw materials needed /extracted / quarried
    • • (more) heat / energy / fuel would be needed
    • • (more) carbon dioxide produced
  13. Most power stations in the UK burn coal . Coal was formed from tree-like planst over millions of years . Suggest why burning wood instead of coal would help to reduce our carbon footprint (3)
    • any three from:
    • • replant trees / renewable /sustainable
    • • carbon (dioxide) used by trees /photosynthesis
    • • it is a (continuous / carbon) cycle or carbon (dioxide) goes back into the air
    • • no new carbon (dioxide) is produced or no locked up carbon (dioxide) is released or the carbon (dioxide) was absorbed millions of years ago
  14. Give one reason why Wegner's idea was not accepted in 1915 (1)
    • no / insufficient evidence / proof /explanation
    • accept there were other theories such as a land bridge / solid crust
  15. the theory of plate tectonics is used to explain why earthquakes occur . Explain how earthquakes occur (2)
    • (continental / tectonic) plates move
    • any one from:
    • • (caused by) convection currents (in the mantle)
    • • (driven by) heat (energy) released by radioactive processes / decay
    • • sudden (movement) / vibrations
  16. Calcium oxide is used in a self heating can . The diagram shows a self-heating can designed to raise the temperature of coffee to 60°C .
    The button on the base of the can is pushed . The foil seperator breaks , allowing water to mix with the calcium oxide . After about 3 minutes , the can is opened by the ring pull . Insulating materials are used inside the walls of the can to prevent either of the lips or the fingers from being burned
    1) Explain why the coffee becomes hot
    2) suugest why it is nogt possible to re-use this self heating can
    • 1) (chemical) reaction / react
    • energy / heat released / exothermic

    • 2) any two from:
    • • foil has been broken
    • • ring pull used
    • • quicklime and / or water mixed /reacted and the reaction isnt reversible
  17. Explain how propene molecules form a polymer (3)
    • poly(propene) / polypropene /polypropylene
    • any two from:
    • • double bonds open up / break /become single
    • • propene molecules / monomers /they join / undergo addition polymerisation
    • • form chains / long molecules
  18. explain what the formula Na2CO3 shows about the compound (2)
    the compound is sodium carbonate and contains 2 sodium atoms a carbon atom and oxygen atoms
  19. explain the environmental benifits of using biodiesel as a sustainable , low pollution fuel (3)
    • sustainable: maximum two from:
    • • crops (that produce oil) can begrown in most places owtte
    • • renewable
    • • use less fossil fuels / diesel
    • • use (refined) waste oils low pollution
    • maximum two from:
    • • most emissions are lower or any two named emissions from CO /SO2 / PM10 are lower
    • • much / lot less SO2 emissions (than the others) owtte
    • • accept spillages / waste is biodegradable
    • • less new CO2 or (more) carbon neutral
  20. Crude oil is the source of many useful materials . Crude oil is seperated into fractions by fractional distilation
    Describe how the Naptha fraction seperates from the other fractions
    • any two from:
    • • naphtha has a different / low(er)boiling point
    • • condenses at a differenttemperature / height / place in the column / when it reaches itÂ’s boiling point
    • • different size of molecules
  21. suggest 2 reasons why all alkanes with fewer carbon atoms are better fuels than the alkane with the formula
    C30H62 (2)
    • any two from:
    • • low boiling point / volatile
    • • low viscosity
    • • high flammability
    • • small molecules
    • • burn completely
  22. the burning of fossil fuels has caused the % of carbon dioxide in the atmosphere to increase above 0.03% . Explain why (2)
    • increase in burning fossil fuels
    • locked up carbon is released

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