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    (Original post by Desouza123)
    Yeah size was changing so surely its the mass but not sure
    It was definitely the concentration of hydrochloric acid, and the mass of the Magnesium!
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    (Original post by harryleavey)
    I ticked mass and the concentration
    Was they the 2 boxes ontop of one another ?
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    (Original post by txa98)
    what did you put for the 2 fill in the gaps sentences talking about molecular mass and stuff..... I put grams and then hydrogen

    it was grams then 12(SUPERSCRIPT) Carbon isotope
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    (Original post by maxjackson5)
    It had such confusing wording, I can't remember either ahha. It was something about which atom can you use to compare the mass of other atoms with
    If it was that, I know that we always compare the mass of other atoms to the mass of Carbon - 12. It's just the universal way of comparing it (:
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    (Original post by hld123)
    I put aluminium oxide instead of bauxite for the electrolysis question. Is that wrong?
    Yes that is completely wrong. The answer is Sodium Chloride.
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    (Original post by Jules12345)
    Wasn't it size of Chip rather than mass?
    It was mass because cutting/changing the size of the chips does not change the mass. Also, the experiment was testing for the change in surface area so it cannot be the size of the marble chips which stayed the same.
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    (Original post by zc555)
    Does anyone have any predictions for an A and an A* (grade boundaries) for C3?

    I think around 45/44 for C3, A star but thats just me
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    Could you just put "Carbon" instead of "Carbon-12"?
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    C3 was really easy, however, C2 was not.

    The question was "A mole is relative atomic mass in _________"

    What was the blank? I was clueless.
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    (Original post by RotomGuy)
    C3 was really easy, however, C2 was not.

    The question was "A mole is relative atomic mass in _________"

    What was the blank? I was clueless.
    grams
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    (Original post by TheTruthTeller)
    Where did I go wrong for the emperical formula; I got PbO3 btw not Pb203Ok so I divided firstly the mass of the lead by the ar i think it was 207 and got like 0.015Did the same for the oxygen and got like 0.045Then I didivided 0.015 by 0.015 and got 1Then I divided 0.045 by 0.015 and got 3Would I get any marks?Where did i go wrong??

    Moles were

    :Pb - 0.03

    O - 0.045

    Divide both by smallestnumber / times by ten:

    Pb - 1 or 3

    ob - 1.5 or 4.5

    times by 2 to get whole number / times by 2 then simplify:

    Pb - 2

    O - 3

    Pb 2 O 3
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    (Original post by Palette)
    Would they allow alumina​ for bauxite?

    no u have to put aluminum OXIDE
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    (Original post by RotomGuy)
    C3 was really easy, however, C2 was not.

    The question was "A mole is relative atomic mass in _________"

    What was the blank? I was clueless.
    A mole is relative atomic mass in grams.
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    (Original post by Bigpaddy27)
    For the poly ethene one could you say it was a reversible reaction

    no its is based on reaction conditions and catalyst
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    (Original post by ansas032)
    Could you just put "Carbon" instead of "Carbon-12"?
    Hope so, thats what I did. I think it would be very harsh if not...
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    (Original post by TheMarkScheme)
    Yes that is completely wrong. The answer is Sodium Chloride.
    pretty sure you are thinking of the wrong question as sodium chloride has nothing to do with the extraction of aluminium...
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    I got 4740 or something along those lines:/
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    for the total volume of acid in C3, last question did anyone put 35 or is that just me (5cm3 of hydrochhloric acid plus 30 more???)
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    (Original post by unknowntsr)
    no u have to put aluminum OXIDE
    The Hall–Héroult process is the major industrial process for smelting aluminium. It involves dissolving aluminium oxide (alumina) in molten cryolite, and electrolysing the molten salt bath, typically in a purpose-built cell.

    Same thing (alumina and aluminium oxide).
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    (Original post by unknowntsr)
    for the total volume of acid in C3, last question did anyone put 35 or is that just me (5cm3 of hydrochhloric acid plus 30 more???)
    i was gunna put that but put 30 instead):
 
 
 
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