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    (Original post by MathsNerd1)
    Isn't it just a solvent? And isn't it the phase that moves in chromatography?


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    yes correct ! but you have to be more specific though

    my turn
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    (Original post by otrivine)
    I finished revision and just doing papers, like legacy

    Define Rf
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    Distance moved by compound/ distance moved by solvent front



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    (Original post by otrivine)
    yes correct ! but you have to be more specific though

    my turn
    Would ethanol work?

    Explain how HLPC works (4)


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    (Original post by MathsNerd1)
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    Distance moved by compound/ distance moved by solvent front



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    yup!

    my turn
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    (Original post by MathsNerd1)
    Would ethanol work?

    Explain how HLPC works (4)


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    is this another word for GC-MS
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    (Original post by ak_bang)
    Errrrr well UMS grade boundaries are already fairly high due to the fact that 90% of students recieve help from their teachers. Do you expect students like me, who have to do the practicals under exam conditions, to sit here while everyone else seems to have an unfair advantage? I don't think so love
    stop getting emotional
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    (Original post by otrivine)
    is this another word for GC-MS
    HLPC is high liquid pressure chromatography, do you know the process for it?


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    (Original post by MathsNerd1)
    HLPC is high liquid pressure chromatography, do you know the process for it?


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    Have no clue whats so ever

    Did I miss a page in the book :confused:
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    (Original post by otrivine)
    Have no clue whats so ever

    Did I miss a page in the book :confused:
    Maybe it's not asked about then, what about column chromatography?


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    (Original post by MathsNerd1)
    Maybe it's not asked about then, what about column chromatography?


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    yes column chromatogrppahy is to do with Gas chromatography

    please tell me what is HPC thingy:confused: worried now
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    (Original post by otrivine)
    yes column chromatogrppahy is to do with Gas chromatography

    please tell me what is HPC thingy:confused: worried now
    1) Sample if dissolved into suitable solvent
    2) Added to the top of a column a liquid eluent (mobile phase)
    3) This mobile phase is then forced through the column via pressure
    4) The different components of the sample has different strengths of interaction with the stationary phase.
    5) Therefore time varies with samples - the time taken for a particular sample is called the "retention time" and is a unique characteristic to that particular sample

    You can check with a data base to see what type of compounds the sample contains
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    (Original post by posthumus)
    1) Sample if dissolved into suitable solvent
    2) Added to the top of a column a liquid eluent (mobile phase)
    3) This mobile phase is then forced through the column via pressure
    4) The different components of the sample has different strengths of interaction with the stationary phase.
    5) Therefore time varies with samples - the time taken for a particular sample is called the "retention time" and is a unique characteristic to that particular sample

    You can check with a data base to see what type of compounds the sample contains

    is this in ur syllabus for edexcel?
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    (Original post by otrivine)
    yes column chromatogrppahy is to do with Gas chromatography

    please tell me what is HPC thingy:confused: worried now
    Basically and it's nothing to worry about if its not in the book, I've been using knockhardy and its on there so that's why I asked.


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    (Original post by MathsNerd1)
    Basically and it's nothing to worry about if its not in the book, I've been using knockhardy and its on there so that's why I asked.


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    OK

    Suggest a use for NMR (1)
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    (Original post by posthumus)
    1) Sample if dissolved into suitable solvent
    2) Added to the top of a column a liquid eluent (mobile phase)
    3) This mobile phase is then forced through the column via pressure
    4) The different components of the sample has different strengths of interaction with the stationary phase.
    5) Therefore time varies with samples - the time taken for a particular sample is called the "retention time" and is a unique characteristic to that particular sample

    You can check with a data base to see what type of compounds the sample contains
    Yes Sorry if I'm trespassing
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    (Original post by otrivine)
    OK

    Suggest a use for NMR (1)
    To identify compounds within a substance?


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    (Original post by MathsNerd1)
    To identify compounds within a substance?


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    Yes good

    my turn
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    (Original post by otrivine)
    Yes good

    my turn
    Okay, explain why TMS is used as the reference substance in NMR? (2)


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    (Original post by MathsNerd1)
    Okay, explain why TMS is used as the reference substance in NMR? (2)


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    because TMS is used standard because it has a chemical shift of 0ppm and so could be used for comparison with other chemical shift peaks which are greater than 0ppml
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    (Original post by otrivine)
    because TMS is used standard because it has a chemical shift of 0ppm and so could be used for comparison with other chemical shift peaks which are greater than 0ppml
    I was thinking because its got 12 hydrogens in the same environment making it the most stable, therefore putting it as the standard. But what you said was correct too.


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