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AS and A2 chemistry practical exams 2013 CCEA watch

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    (Original post by condor789)
    Yeah you got all that right except it was zinc sulfate, the white precipitate dissolved in excess NH3, though it was really hard to tell!
    This is for the A2 module right?
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    I knew 7 was my lucky number for a reason. I thought I'd messed up the value of x, so glad to hear other people got the same

    I also got zinc and ammonium sulfate, -oh present and c=c absent

    Can anyone remember what they got for the percentage yield question?
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    (Original post by krisachick)
    I knew 7 was my lucky number for a reason. I thought I'd messed up the value of x, so glad to hear other people got the same

    I also got zinc and ammonium sulfate, -oh present and c=c absent

    Can anyone remember what they got for the percentage yield question?
    I got 79.1% but others got around 30%? I think I made a mistake with the rfm
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    (Original post by Aaroncarlisle)
    This is for the A2 module right?
    No lol. A2 was hydrated chromium (iii) chloride and propanoic acid
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    How did everyone test for carbonate ions?


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    (Original post by MatthewG_94)
    How did everyone test for carbonate ions?


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    Limewater it didn't say about distinguishing between carbonate and hydrogen carbonate


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    I though it was alright I got Ammonium Sulphate but I wrote Magnesium Sulphate, for the other salt because of the white crystalline solids being group 1, 2 or ammonium salts. I completely messed up the organic question I said that there was a c=c group present and that the hydroxyl group was absent :P Ah well apart from that
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    (Original post by MatthewG_94)
    How did everyone test for carbonate ions?


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    Apparently it is Magnesium Nitrate. They'll accept Magnesium Chloride. It will form a white ppt. when in contact with CO3 ions.
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    (Original post by toreilly102)
    Apparently it is Magnesium Nitrate. They'll accept Magnesium Chloride. It will form a white ppt. when in contact with CO3 ions.
    Ahh I knew it was a solution of magnesium ions that had to be added but I thought the magnesium ions could come from anything so I just out magnesium sulphate solution!


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    (Original post by UnknownError)
    Limewater it didn't say about distinguishing between carbonate and hydrogen carbonate


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    Limewater tests for CO2, think the answer was magnesium chloride or nitrate.
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    (Original post by condor789)
    Limewater tests for CO2, think the answer was magnesium chloride or nitrate.
    You can add carbonate to dilute HNO3 and collect the gas and bubble it through limewater


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    (Original post by UnknownError)
    You can add carbonate to dilute HNO3 and collect the gas and bubble it through limewater
    But wouldn't a hydrogen carbonate give the same result?
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    (Original post by ChrisBee)
    But wouldn't a hydrogen carbonate give the same result?
    Yeah but it's still proving carbonate ions are present


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    I can't remember but was the water of crystallisation value depend on your titration value.


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    (Original post by UnknownError)
    Yeah but it's still proving carbonate ions are present


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    The wanted proof of carbonate ions, not hydrogen carbonate. Pretty sure they wont accept that answer
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    (Original post by condor789)
    The wanted proof of carbonate ions, not hydrogen carbonate. Pretty sure they wont accept that answer
    I think they would as it does test for carbonate ions, maybe loss 1 mark if any. I may be wrong but I thought that as mg was in the thing anyway you could assume that there were no hydrogen carbonate ions.


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    How did you do the first question? How did you get a 250cm^3 sol^ of the mass? Was it divide by 4?
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    (Original post by Aaroncarlisle)
    How did you do the first question? How did you get a 250cm^3 sol^ of the mass? Was it divide by 4?
    I divided 11.60gdm3 by 4 bt im not too sure about it :/ wht did everyone else do?
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    I did the same thing! Yay! Why was using a water bath good?
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    (Original post by Aaroncarlisle)
    I did the same thing! Yay! Why was using a water bath good?
    I just said because it heats gently, not sure if that would get the mark but it seems reasonable doesn't it?


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