GCSE Chemistry

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ghoran
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158363
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GCSE Chemistry
Updated:
2012-06-13 13:26:30
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  1. The chemical equation for a reaction of sodium is shown below
    2Na + Cl2 ==> 2NaCl
    desrcibe this reaction in terms of the names of the substances and the atoms involved
    (3)
    • 2 sodium atoms react
    • with 2 chlorine atoms
    • 2 sodium ions and 2 chlroine ions are produced
  2. poly(ethene) molecules are made from ethene molecules by a polymerisation reaction
    describe what happens in a polymerisation reaction
    (2)
    • many monomers/ethenes
    • join/bond togther
  3. what are the positive environmental effects of reusing plastic bags
    • • used to make new plastic bags / objects
    • • saves raw materials / crude oil
    • • saves energy compared to producing plastic bags from crude oil
    • • cuts down on CO2 emissions
    • • less global warming
  4. what are the negative environmental impacts of reusing plastic bags
    • • collection point sites cause an eyesore / litter problem
    • • transportation to recycling plant releases carbon dioxide / causes global warming
  5. what are the positive enviornmental impacts of burning plastic to release energy
    • • could provide energy for heating buildings
    • • could provide energy for generating electricity
  6. what are the negative environmental effects of burning plastics to produce energy
    • • increases CO2 emissions
    • • increases global warming
    • • could release toxic gases
    • • does not conserve raw materials / crude oil
  7. suggest two pieces of evidence that may have led Wenger to purpose his hypothesis that continents move
    • the continents of South Americaand Africa would have fittedtogether like a jigsaw
    • there are matching / similar rocks/ fossils on the continents ofSouth America and Africa
  8. suggest why in 1920 , other scientist thought that Wegners hypothesis was wrong
    • Wegener had no evidence to prove that continents can move
    • and that a land bridge couldexplain the matching fossils on the continents of South America and Africa
  9. Copper is found in the Earths crust as an ore containing copper sulfide . Large areas of land , where this ore was once quarried , are contaiminated with low percentages of copper sulfide . Copper would be too expensive to extract from this contaminated land using the traditional method of quarrying then heating in a furnace . The percentage of copper ore in the contaminated land is low
    it would be too expensive to extract from this land by the traditional method , explain why (1)
    large amounts of energy would be needed to extract copper
  10. Copper is found in the Earths crust as an ore containing copper sulfide . Large areas of land , where this ore was once quarried , are contaiminated with low percentages of copper sulfide . Copper would be too expensive to extract from this contaminated land using the traditional method of quarrying then heating in a furnace . The percentage of copper ore in the contaminated land is low
    extracting copper from this land by the traditional method would have a major environmental impact , give one reason why (1)
    • any one from
    • produces large amounts of solid waste
    • atmospheric pollution from carbon dioxide and suplhur dioxide
    • more lorries and more traffic
  11. it is possible to get copper from a solution of copper sulphate using scrap iron
    It is economical to use scrap iron to get copper
    give on ereason why (1)
    iron is cheap
  12. why can iron be used to get copper from copper sulphate solution
    iron displaces copper from the solution of its salts
  13. a new way to extract copper from land that contains low percentages of copper ore is phtomining . Phytominig uses plants . Plants are grown on this land and absorb copper compounds through their roots . Use this imformation to give two advantages of phtoming compared to the traditional method (2)
    • any two from:
    • • less expensive/energy toextract the small amountsof copper
    • • plants will remove carbondioxide from theatmosphere as they grow
    • • can release energy whenplants are burned
  14. a new way to extract copper from land that contains low percentages of copper ore is phtomining . Phytominig uses plants . Plants are grown on this land and absorb copper compounds through their roots . Use this information to suggest one disadvanatge of phytomining compared to the traditional method (1)
    not continuous as it takes a long time for plants to grow
  15. hydrocarbon J burns completely in oxygen to produce carbon dioxide and water vapour
    2C8H18 + 25O2 ===> 16CO2 + H2O
    When 114g of hydrocarbon J burns completely in 400g of oxygen it produces 162g of water vapour and 352g of carbon dioxide
    the mass of carbon dioxide produced is greater than the 114g of hydrocarbon J that was burned , explain why (2)
    because 2 molecules ofhydrocarbon J had 25 moleculesof oxygen added
  16. process 1
    fermentation of sugar solution by yeast in a reaction vessel. the reaction vessel has to be emptied , cleaned and refilled every few days. The process produces 15% ethanol solution in water
    process 2
    reaction of ethene (from crude oil) with steam in a reactor . The reaction is only stopped if there is a fault in the reactor . The process produces 100% ethanol
    give one advantage that process 1 has over process 2 (1)
    raw materials are renewable
  17. process 1 fermentation of sugar solution by yeast in a reaction vessel. the reaction vessel has to be emptied , cleaned and refilled every few days. The process produces 15% ethanol solution in waterprocess 2 reaction of ethene (from crude oil) with steam in a reactor . The reaction is only stopped if there is a fault in the reactor . The process produces 100% ethanol
    what advantages to a manufacturer of ethanol does process 2 have over process 1 (2)
    • alcohol does not need to be distilled
    • process is continuous
  18. Air is a mixture of gases and contains various pollutants . The gases are useful and can be seperated by fractional distillation of liquid air . The table gives information about some of the gases in air
    to seperate these gases :
    the air is filtered
    water is removed first
    carbon dioixde is then removed by absorption
    the gases remaining are compressed and cooled to -200°C
    the air is filtered before the gases are sperated
    suggest why
    to removed the dust
  19. Air is a mixture of gases and contains various pollutants . The gases are useful and can be seperated by fractional distillation of liquid air . The table gives information about some of the gases in air
    to seperate these gases :
    the air is filtered
    water is removed first
    carbon dioixde is then removed by absorption
    the gases remaining are compressed and cooled to -200°C
    Water vapour and carbon dioxide are removed before the gases are compressed andcooled.Use the information in the table to suggest why.
    because at –200°C both are solidsthis would therefore block pipes
  20. Air is a mixture of gases and contains various pollutants . The gases are useful and can be seperated by fractional distillation of liquid air . The table gives information about some of the gases in air

    to seperate these gases :the air is filtered water is removed first carbon dioixde is then removed by absorption the gases remaining are compressed and cooled to -200°C
    After the water and carbon dioxide have been removed, which gas stays liquid over thegreatest temperature range?
    oxygen
  21. Air is a mixture of gases and contains various pollutants . The gases are useful and can be seperated by fractional distillation of liquid air . The table gives information about some of the gases in air
    to seperate these gases :the air is filteredwater is removed firstcarbon dioixde is then removed by absorptionthe gases remaining are compressed and cooled to -200°C
    After the water and carbon dioxide have been removed, the four gases that are left arecompressed and cooled to –200 oC.
    Which gas does not liquefy?
    helium
  22. Air is a mixture of gases and contains various pollutants . The gases are useful and can be seperated by fractional distillation of liquid air . The table gives information about some of the gases in air
    to seperate these gases :the air is filteredwater is removed firstcarbon dioixde is then removed by absorptionthe gases remaining are compressed and cooled to -200°C
    The three liquefied gases are then allowed to warm up.Give the order in which the three liquefied gases would vaporise
    • nitrogen
    • argon
    • oxygen
  23. reaction of ethene with steam to produce ethanol is known as
    hydration
  24. Limestone contains the compound calcium carbonate , CaCO3 . Limestone is used to make cement in a rotary kiln . Name two main waste gases from this rotary kiln
    • water vapour
    • carbon dioxide
  25. columns used as supports for buildings can be made from materials such as limestone blocks or concrete . Why may people think that concrete is a better material for making a column (3)
    • any three from
    • • raw materials are abundant
    • • can be reinforced (by steel rods) /strong(er) / supported (by steel rods)
    • • concrete mixture can be poured /moulded / constructed on site
    • • less reactive with acid rain /weathering / erosion
  26. columns used as supports for buildings can be made from materials such as limestone blocks or concrete . Why may people think that limestone is a better material for making a column (3)
    • any three from
    • • abundant / local
    • • natural material or no ‘processing’needed
    • • relatively easy to cut
    • • appearance better
  27. copper oxide , CuO , is reduced using carbon . Describe and explain what happens in this reaction
    • any two from:
    • • heat (copper oxide with carbon)
    • • oxygen is removed by carbon carbon dioxide is
    • produced or carbon displaces copper
    • • because carbon is more reactive than copper
  28. copper rich ores are running out
    New ways of extracting copper from low grade ores are being researched . Recycling of copper may be better than extracting copper its ores explain why
    • any three explanations from:
    • • less acid rain (pollution)
    • • copper reserves last longer / conserved or do not run out
    • • energy for extraction (saved)or less energy required
    • • less mining / quarrying
    • • less waste (copper) / electrical appliances dumped or less landfill
  29. in general recyling is good because it
    • saves resouces
    • uses less energy
    • usese less fossil fuels
    • less pollution of carbon dioxide and sulphur dioxide into the atmosphere
    • less waste rock
    • less landfill
    • however these points must be linked to the question being asked e.g. recycling copper conserves copper ore
  30. scientists cannot accurately predict when earthquakes will occur .
    explain why (4)
    • plate (boundaries)
    • sudden movement / colliding
    • or
    • normally move a few centimetres per year
    • convection currents / driven by heat from radioactive processes / decay
    • the idea of uncertainty with an explanation eg scientists do not know (with any certainty)
    • • what happens under the crust
    • • where the forces / pressure are building up
    • • we cannot measure the forces
    • • when the forces reach their limit
  31. the ingredients of soft margerine include hydrogenated vegetable oil
    why is hydrogenated vegetable oil used in soft margerine (1)
    • any one from:
    • • have a higher melting point than(vegetable) oil
    • • are solid at (room temperature) /hardened / harder
  32. ethanol can be made using either sugar or alkanes such as the starting material . Evaluate the advantages and disadvantages of using these two starting materials to produce ethanol
    **!!!!!!NO NEED TO COMPARE , THE QUESTION DOES NOT ASK YOU TO COMPARE , RTQ !!!!!!!**
    • advantages of using sugar
    • • country has no wealth to buy (large quantities of) crude oil
    • • country has limited technological development or underdeveloped / third world country
    • • able / suitable climate to grow sugar cane
    • • enough land to grow sugar cane / land cannot be used to grow food /deforestation
    • • sugar is a renewable source or crude oil is a non-renewable resource /finite resource / limited resources
    • • CO2 / carbon neutral
    • advantages of using alkanes:
    • • economic costs are low
    • • continuous process
    • • country has large oil resources
    • • country has oil refineries / cracking plants
    • • very pure product
    • • faster process

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