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    Just use LiAlH4 in dry ether!!

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    (Original post by Wahid1)
    We established that there's no need for the use of volumes in this scenario.

    The question was about the difference in values which arises from their laziness


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    Haha!


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    (Original post by madmenace)
    Just use LiAlH4 in dry ether!!

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    That's the only way i know how too haha


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    (Original post by Wahid1)
    We established that there's no need for the use of volumes in this scenario.

    The question was about the difference in values which arises from their laziness


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    Wait.. Im a bit confused still.. Whats the 0.6 all about?


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    (Original post by baymax96)
    Attachment 423773 what is the reason for the chloride ion conc being 0.2?

    also please can someone show me how to solve these questions! I'm so confused as to what i'm doing wrong
    Attachment 423773423775 the answers are A, D and C

    These questions are from the sample assessment paper
    thank you in advance!
    The sample assessment:

    Q10)

    a) and b) are both:

    Work out excess mols then:

    c=1000n/v pH = -log(c)

    c) NEVER use UNIVERSAL for Acid-base titrations!

    You know it's not going to be A or B now. Sort of obvious but won't be D so you could use process of elimination or work out the pH from b) and this should give you the end point, and equivalence point will be below that (hence why I'm doubting D).
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    (Original post by Nautic4l)
    Thank you, but what about for any other questions in which they ask? Is the clue in the question usually?
    Yup, the question makes it clear, or they assume you have basic chemistry knowledge/common sense to know the standard states of some chemicals (e.g.- water is liquid, etc.) But most times, it should be fairly obvious, and if not, the mark scheme usually does not distinguish between aq/l in many cases if both are factually correct. Good luck!
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    (Original post by MeeraP07)
    Wait.. Im a bit confused still.. Whats the 0.6 all about?


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    the volume of the container in dm^3
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    (Original post by Wahid1)
    I would be inclined to say no because the reducing agent mentioned in our course is LiAlH4


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    Thanks! Turns out our teachers have been teaching us wrong :P
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    (Original post by madmenace)
    Just use LiAlH4 in dry ether!!

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    Does it matter if you say dry ether or dry diethyl ether? Does it make a difference?
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    (Original post by MeeraP07)
    Wait.. Im a bit confused still.. Whats the 0.6 all about?


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    It's the volume which you can disregard but they're being dip****s about it


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    (Original post by AffirmedCube)
    Does it matter if you say dry ether or dry diethyl ether? Does it make a difference?
    I think so?

    Just say dry ether to be on the safe side


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    (Original post by Katameringue)
    Quick question: can you reduce a ketone/aldehyde C=O bond with excess hydrogen and a catalyst? 'Cause my notes say one thing, but a markscheme I just looked at says another
    No, the H2/Pt combination reduces C=C, but not C=O. To reduce C=O, LiAlH4 is typically used.
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    (Original post by Katameringue)
    Quick question: can you reduce a ketone/aldehyde C=O bond with excess hydrogen and a catalyst? 'Cause my notes say one thing, but a markscheme I just looked at says another
    June 2014 IAL has a question regarding an organic compound reacting separately with excess Hydrogen with Nickel catalyst and LiAlH4.
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    Can someone link me some questions on identifying organic compounds e.g. NMR, spectroscopy and that stuff, can't find any anywhere.
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    (Original post by ArielHaeems)
    No, the H2/Pt combination reduces C=C, but not C=O. To reduce C=O, LiAlH4 is typically used.
    in the george facer book it says h2/pt can be used as well but i think its best to say LiAlH4
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    (Original post by Hairysweets)
    The sample assessment:

    Q10)

    a) and b) are both:

    Work out excess mols then:

    c=1000n/v pH = -log(c)

    c) NEVER use UNIVERSAL for Acid-base titrations!

    You know it's not going to be A or B now. Sort of obvious but won't be D so you could use process of elimination or work out the pH from b) and this should give you the end point, and equivalence point will be below that (hence why I'm doubting D).

    Ok so for a, excess moles would be 25-24.95/1000 x 1? which = 5x 10^-5

    but i'm still not getting the answer:/

    SORRY just realised my mistake!! i understand now

    thankyou!!
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    (Original post by Maham88)
    in the george facer book it says h2/pt can be used as well but i think its best to say LiAlH4
    Oh, that's weird. Could you tell me which page that is, if possible? I have the book right here.
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    i thought they all can be attacked equally from above and below the plane?
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    I'm really struggling with drawing titration curves! I only ever score a max of 2 in them. How do you how many units it should be and what the pH is at 25cm^3?
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    May someone please explain to me what the experiment with iodine and propanone is about?
    would be a great help!
 
 
 
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