GCSE Chemistry

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GCSE Chemistry
2012-04-06 06:52:36

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  1. what are the advantages of bio-leaching
    • the costs of seting up this bio-leaching is low
    • it does not need huge open cast mines that scar the landscape
    • bacteria can get the copper from low grade ores or waste
    • it uses a lot less energy and does not produce sulfur dioxide gas as in smelting sulfied ores
    • it can be used on ores that would pollute the air when smelted
  2. what are the disadvantages of bioleaching
    • biol-leaching does not recover precious metals , so this reduces profits for the copper refiners
    • sometimes acid has to be added to the ore - which costs money
    • sometimes the bacteria themselves produce too much acid - which has to be neutralised again this cost more money
    • it can take years to extract only 50% of the copper from the ores . So reasearch continues to speed up the action of the bacteria . However , as sources of high grade copper ore run out , bio-leaching will get more and more important
  3. purification of copper - copper is a very good ..... of electricity , it is used for electrcial ..... and cables . However small amountos of ..... cut down this conductivity quite noticeably . to ensure a high level of purity newly extracted copper had to be ...... by ..... . the electrolyte is ..... ..... . when the current flows , the copper moves from the .... electrode to the .... elctrode . any .... fall to the bottom of the cell and collect below the ... electrode in the from of ..... . this .... is rich in precious .... and the recovery of these metals is an important aspect of the economies of the process
    • conductor
    • wiring
    • impurities
    • purified
    • electrolyisis
    • copper sulphate
    • impure
    • pure
    • impurities
    • +
    • slime
    • slime
    • metals
  4. how can we concentrate copper carbonate write a balanced symbol and word equation
    • copper carbonate [heat]====> copper oxide + carbon dioxide
    • CuCO3{heat}===> CuO + CO2
  5. how can we extract copper oxide
    write a word equation and balanced symbol equation
    • by smelting
    • copper oxide + carbon =====> copper + carbon dioxide
    • 2CO + C ====> 2Cu + CO2
  6. how can we extract copper sulphate , write a word equation and balanced symbol equation
    • scarp iron can be used in a displacement reaction because iron is higher in the reactivity series than copper
    • Copper sulphate + iron ====> iron sulphate + copper
    • CuSO4 + Fe ====> FeSO4 + Cu
  7. Explain how the blast of air in a blast frunace helps to raise the temperature
    because it allows the coal to burn faster because the air contains oxygen which will burn with the coal to produce CO2 , a waste gas in the blast furnace
  8. limestone reacts with any sand ( SiO2 ) in an iron ore to form calcium silicate . Comlpete the balanced chemical equation

    CaCO3 + SiO2 ===> CaSiO3 + .........
  9. write a word equation for the extraction or iron in a blast furnace
    iron oxide + carbon ====> iron + cabron dioxide
  10. if iron oxide is Fe2O3 write a balanced symbol equation for the extraction of iron in a blast frunace
    2Fe2O3 + 3C ====> 4Fe2 + 3CO2
  11. explain why copper cant be extracted from 1% copper ore in ablast frunace
    because there would be too much waste produced and it would be very inefficient
  12. exlpain why copper collects at the negative terminal during electrolysis
    because it wants to collect 2e- in order to become a neutral copper atom , and oppisites attract
  13. draw a flow chart for the production of copper from low grade ores by leaching
    • soak copper in acid or water
    • are the copper compounds leached out - if no repeat the above stage , if yes move onto the next stage
    • remove the copper from the lechate by electrolysis
  14. can you suggest a method for cleaning up rivers polluted with copper salts ? what are the disadvanatges
    • Iron is more reactive than copper salts so if we put scarp iron in these rivers , the iron will then displace the copper from the solution . the copper can then be refined and collected
    • however there are many disadvantages
    • the river will then be polluted with iron salts
    • ans somebody could steal the scrap iron
  15. in general recycling
    • saves resources
    • saves energy
    • reduces pollution
    • reduces mining
  16. what are the neagtives or recycling
    people need to collect and sort the recycled items , this will involve paying labourers , also the vechiles are expensive to use in terms of tax and fuel , and also burning fuel produces carbon dioxide which leads to global warming
  17. draw a flow chart to show the process of recycling
  18. phtomining - the plants which absorb metal compounds are called
  19. we can extract cobalt , nickel and cadimium using phytomining from the :
    brasicas family
  20. what are the brasiscas family otherwise known as
    the cabbage family
  21. what is an advanatge of phytoming
    • it is cheap
    • doesnt release any greenhouse gases
    • sustainable
  22. what are the disadvantages of phytomining
    • the planst will struggle to survive as they are purposley put in areas where the soil contains metal ores , therefor it is too toxic for the soil and plant
    • for sucess you are relying on the plant and many things could affect the plants such as the weather , without a healthy plant your extraction may not be sucessfull