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Chemistry AS Evaluative Practical F323 Watch

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    Right, we've been given an evaluative task on the preperation of a ketone which happens to be propan-2-one. So i'm assuming, as this is a written paper, so what do you think would come up?

    Would I just have to explainthe process of making propan-2-one from an alchol.. ie. a secondary alchol such as propan-2-ol .. and you just heat with Pottasium Dichromate, and reflux, and the Pottasium Dichromate is reduced and changes colour from orange to green.

    To determine further, whether its an Aldehyde or a Ketone, I could use 2,4 DNP (Bradley's Reagent) and an Orange precipitate would form.. Then to test whether it is an Aldehyde or a Ketone, I could use Tollen's Reagent. With an Aldehyde, this would just oxidise to a Carboxylic Acid and a silver mirror would appear on this side of a test tube; Ketones are not oxidised by this Reagent.

    Alternatively, to determine if it is a Ketone, you could prepare a Crystaline Derivative using the Orange precipitate formed from the 2,4 DNP by filtering the impure product, and recrystillising it to produce a pure sample of yellow/orange crystals of the 2,4 DNP derivative. You can then test it's melting point, and compare the result with a database of the melting points of aldehydes and ketones..

    What else would I need to know for this test, other than Mole calculations, and how to test for the presence of a Ketone?
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    Right, so no one else doing this tommorow?? I see....
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    (Original post by Haz Shah)
    Right, we've been given an evaluative task on the preperation of a ketone which happens to be propan-2-one. So i'm assuming, as this is a written paper, so what do you think would come up?

    Would I just have to explainthe process of making propan-2-one from an alchol.. ie. a secondary alchol such as propan-2-ol .. and you just heat with Pottasium Dichromate, and reflux, and the Pottasium Dichromate is reduced and changes colour from orange to green.

    To determine further, whether its an Aldehyde or a Ketone, I could use 2,4 DNP (Bradley's Reagent) and an Orange precipitate would form.. Then to test whether it is an Aldehyde or a Ketone, I could use Tollen's Reagent. With an Aldehyde, this would just oxidise to a Carboxylic Acid and a silver mirror would appear on this side of a test tube; Ketones are not oxidised by this Reagent.

    Alternatively, to determine if it is a Ketone, you could prepare a Crystaline Derivative using the Orange precipitate formed from the 2,4 DNP by filtering the impure product, and recrystillising it to produce a pure sample of yellow/orange crystals of the 2,4 DNP derivative. You can then test it's melting point, and compare the result with a database of the melting points of aldehydes and ketones..

    What else would I need to know for this test, other than Mole calculations, and how to test for the presence of a Ketone?

    how did you find the evaluative task? doi need to know expt errors? help?
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    (Original post by *SHAI*STAR*)
    how did you find the evaluative task? doi need to know expt errors? help?
    Ha! I got worried about the error percentage, because we were forced to do that last year..! but in this one, i don't think so But its better to learn how significant figures work etc..
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    hey, i have this practical on thursday and really need a good grade :/ could you like tell me what is definitely going to come up so i fully cover the topic, because im terrible at practicals.. thanks
 
 
 
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