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Edexcel IAL Chemistry (WCH06/01) Chemistry Laboratory Skills II - 10th May 2016 Watch

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    (Original post by pondsteps)
    i put thermometer and flask
    and i didnt know the third so i put smthn to connect between flask and condenser lol
    I did like this :
    1)thermometer
    2)stopper/bung
    3)A conical flask with vent , to collect distillate
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    (Original post by CPSohan)
    I did like this :
    1)thermometer
    2)stopper/bung
    3)A conical flask with vent , to collect distillate
    ugh i crossed out stopper last minute
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    (Original post by pondsteps)
    ugh i crossed out stopper last minute
    Itz ok, and I don't think a 'stopper' is considered as 'apparatus' , but I wrote it anyway bcuz I couldn't find anything better :/
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    (Original post by wima3109)
    you just have to say if that error would make a significant change
    do u remember which ones u put as valid or not?
    i put 1st 2nd 4th .. by valid i meant it would make a significant change - is my answer correct

    and what did u guys put as the test for iodine????
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    that paper was kinda messed up....really hope the boundaries will be low...
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    (Original post by wima3109)
    that paper was kinda messed up....really hope the boundaries will be low...
    Ikrrr.. but i dont think they have ever fallen below 30 .. last year it was 31 and it was easier
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    (Original post by pondsteps)
    do u remember which ones u put as valid or not?
    i put 1st 2nd 4th .. by valid i meant it would make a significant change - is my answer correct

    and what did u guys put as the test for iodine????
    i put the heat loss thingy and the incomplete combustion of alcohols......for the iodine thing i put starch solution turns blue black to colourless.....hope i am correct
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    (Original post by CPSohan)
    Itz ok, and I don't think a 'stopper' is considered as 'apparatus' , but I wrote it anyway bcuz I couldn't find anything better :/
    i guess the right answer is adaptor for the third point.. but i couldnt remember its name so i wrote the description of what it is
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    (Original post by pondsteps)
    do u remember which ones u put as valid or not?
    i put 1st 2nd 4th .. by valid i meant it would make a significant change - is my answer correct

    and what did u guys put as the test for iodine????
    -1st and 2nd were not valid , 3rd and 4th were valid.
    - Test for presence of Iodine , which came today in exam , is actually the test for halo-alkane. Hot NaOH(aq.)+ dil.HNO3+ AgNO3 -------------------------------> yellow precipitate forms, showing the presence of I-
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    (Original post by pondsteps)
    Ikrrr.. but i dont think they have ever fallen below 30 .. last year it was 31 and it was easier
    atleast 30 would be okay....
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    (Original post by wima3109)
    i put the heat loss thingy and the incomplete combustion of alcohols......for the iodine thing i put starch solution turns blue black to colourless.....hope i am correct
    yeah u are.. i put the test for iodide by mistake lolol
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    (Original post by CPSohan)
    -1st and 2nd were not valid , 3rd and 4th were valid.
    - Test for presence of Iodine , which came today in exam , is actually the test for halo-alkane. Hot NaOH(aq.)+ dil.HNO3+ AgNO3 -------------------------------> yellow precipitate forms, showing the presence of I-
    OMG are u SUREEEEE!! I PUT THAT TOOO
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    (Original post by wima3109)
    i put the heat loss thingy and the incomplete combustion of alcohols......for the iodine thing i put starch solution turns blue black to colourless.....hope i am correct
    Wima , "starch solution turns blue black to colourless" is for Iodine molecule , I2 . But there was no Iodine molecule , it was a halo-alkane, and when you break C-I bond , you don't get Iodine molecule, rather you get Iodide ions.
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    (Original post by cpsohan)
    wima , "starch solution turns blue black to colourless" is for iodine molecule , i2 . But there was no iodine molecule , it was a halo-alkane, and when you break c-i bond , you don't get iodine molecule, rather you get iodide ions.
    ilysmmmm okay
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    (Original post by pondsteps)
    OMG are u SUREEEEE!! I PUT THAT TOOO
    Of course I am sure, why not ? "starch solution turns blue black to colourless" is for Iodine molecule , I2 . But there was no Iodine molecule , it was a halo-alkane, and when you break C-I bond , you don't get Iodine molecule, rather you get Iodide ions.
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    (Original post by CPSohan)
    Of course I am sure, why not ? "starch solution turns blue black to colourless" is for Iodine molecule , I2 . But there was no Iodine molecule , it was a halo-alkane, and when you break C-I bond , you don't get Iodine molecule, rather you get Iodide ions.
    but the q said how to test for iodine
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    (Original post by pondsteps)
    but the q said how to test for iodine
    No. The question asked us to show the presence of Iodine.
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    (Original post by CPSohan)
    No. The question asked us to show the presence of Iodine.
    it said presence of iodine atoms....i wrote the agno3 thing and cut it and wrote the starch solution......FML
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    (Original post by CPSohan)
    No. The question asked us to show the presence of Iodine.
    great! but all i wrote was add NaOH then nitric acid the silver nitrate and yellow ppt forms.. is it correct??
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