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    U put hot boiling concentrated NaOH in Bauxite (conc NaCl)
    this dissoves the Si2O3 and Al2O3 but does not dissolve Fe2O3
    u then filter it to remove the Fe2O3
    and u bubble CO2 in it.
    this makes Al(OH)3 percipitate
    u filter it and then heat and dry it

    hope that helps!
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    (Original post by chrisbphd)
    Ooh-an advantage of doing and edexcel syllabus.
    took the words right out of my mouth
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    Are you sure its CO2 and not CO?
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    positive!

    i have a hunch this one will come in the exam so i;ve looked thru it
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    Thanks
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    Hi can anyone add me on msn at [email protected] ... i've to cross check a few things on AS chem unit 1,2
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    what about?
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    Can anyone outline the reaction for the production of Nitric acid from ammonia?

    Also include the reaction conditions.
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    Read back I said it already. Oxidise ammonia, then mix with oxygen and water.
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    I found this question in an old paper - It says to write a formula the (delta)H(theta)(at) <-- the 'at' is at the bottom where you'd normally see 'f' or 'c'. I'm confused. What's it asking me to do?
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    (Original post by zombie)
    I found this question in an old paper - It says to write a formula the (delta)H(theta)(at) <-- the 'at' is at the bottom where you'd normally see 'f' or 'c'. I'm confused. What's it asking me to do?
    standard enthalpy of atomisation???

    i.e 0.5H2=>H


    qlthough i thought that was just an a
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    this will be about the enthalpy of atomisation of an element. does it say what element its for?
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    (I2(s))
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    Thanks - A question in the jan 2004 paper Unit 2 states the production of nitric acid from ammonia involves the the oxidation by air using platinum rhodium catalyst . Outline the steps from which nitric acid is then produced.
    (4 Marks)

    I don't have the marking scheme with me at this moment so can anyone tell me what we should write for the 4 marks?
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    wot does acidified potassium dichromate mean???
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    This means that H+ ions are present.
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    (Original post by lgs98jonee)
    wot does acidified potassium dichromate mean???
    in the presence of an acid...

    eg primary alcohol forms carboxylic acid in the presence of acidified pottasium dichromate ( the same as concnetrated sulohuric acid and posttasium dicromate)

    its imp to no if its acidified or not.. u need to no the conditions for the marks...

    pax.. i have the mark scheme sumwhere i'll go have a look...
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    With H+ ions present to mop up the O2s produced in the redox. (Mn)4 loses the oxygens to the hydrogens and forms water.
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    okay guys... some serious help:

    I;ve got 2 papers here the edexcel specimen. Q6
    it has: C2H5OH + 3O2 = 2C02 = 3H20

    The avg bond enthalpies are:
    C-H 412
    C-O 360
    0=O 496
    C-C 348
    O-H 463
    C=O 743

    so the enthalphy change is bonds broken- bonds formed which is 4371-5750 which is -1379

    but the Jan 2002 paper q^ they have
    AH formation for
    c2h4 (ethene) 52.3
    HBr -36.2
    C2H5Br -60.4

    to work out C2H4 + HBr = C2H5Br

    i did bonds broken- bonds formed but in the mark scheme theyve done:
    -60.4 (bond formed) - 16.1 (bonds broken) = -76.5

    i dont get it?!!
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    Thanks can you also check the answer to the part i) of the last question in unit 1 - same year . It is the one about silicon's melting point.
 
 
 
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