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Edexcel Chemistry Unit 5 June 19 2012

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    (Original post by marcus94)
    I remember my teacher saying that the reasoning behind it is beyond a level. As said in a couple of posts in the thread the only ones we should know as being square planar is [pt(nh3)2(cl2)] and [cu(cl)4]2- (Dont take my word for it)
    Oh Ok cheers
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    (Original post by Sykikdoc1993)
    Hey !!
    Whens a complex ion square planar and tetrahedral ?
    The book I am using says a coordination no. of 4 attaching to ligands and complete d-subshells is formed means tetrahedral and vice versa for square planar . I am confused I thought transition metals have incomplete d subshells ?
    I don't think they really ask you about shapes except CuCl42- and CoCl42- (both tetrahedral) or Ni complexes/cisplatin (square planar).
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    (Original post by marcus94)
    yeh exactly =/ Are you sure those equations are right and its not [zn(nh3)6] ??
    These are notes from my teacher, he said its the only one forms 4 dative covalent bonds.

    What does your book say?
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    (Original post by marcus94)
    no you may be thinking of phenol with benzenediazonium ion to make an azo dye.

    Your right... Basically the reaction occurs in two stages this is because Hno2 is very unstable and needs to make in situ : Firstly you need to make the HnO2

    Nano2 + Hcl => HnO2 + Nacl

    the overall reaction is:

    c6h5nh2 +hno2 + 2hcl -> c6h5n2cl + 2h2o
    Ohhh okay, thank you sooo much and if its not too much trouble, can you tell me what I need to know about azo dye as stated before regarding the temperatures and loads of questions on them
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    [QUOTE=Jukeboxing;38170646]These are notes from my teacher, he said its the only one forms 4 dative covalent bonds.

    What does your book say?[/QUOTE
    both my notes and the cgp revision guide agree with you. I think the simple answer is that its not a transition metal so doesnt behave as they would :L rather basic tbh but that was the shrugging coment my teacher gave me when i asked this!
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    (Original post by Jukeboxing)
    These are notes from my teacher, he said its the only one forms 4 dative covalent bonds.

    What does your book say?
    with NaOh it goes to [zn(OH)4]2- and they havent put an equation for when it reactions with ammonia at all

    (Original post by keerthi3)
    Ohhh okay, thank you sooo much and if its not too much trouble, can you tell me what I need to know about azo dye as stated before regarding the temperatures and loads of questions on them
    theres not really anything to know about azo dyes other than how they are made... the ones with temperatures of 0-10 degrees is when you are making the azo dye and diazonium ion
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    (Original post by physics1)
    both my notes and the cgp revision guide agree with you. I think the simple answer is that its not a transition metal so doesnt behave as they would :L rather basic tbh but that was the shrugging coment my teacher gave me when i asked this!
    I've tried looking it up on the internet and couldn't find a reason. Its not part of the syllabus to know why, so we shouldn't worry about.
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    (Original post by Sykikdoc1993)
    Hey !!
    Whens a complex ion square planar and tetrahedral ?
    The book I am using says a coordination no. of 4 attaching to ligands and complete d-subshells is formed means tetrahedral and vice versa for square planar . I am confused I thought transition metals have incomplete d subshells ?
    If its CN- it's square planar, that's the only example I've seen
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    (Original post by marcus94)
    it doesnt, they all have similar effect regardless of the number of alkyl group. Its only when it has a benzene ring when it gets weaker as the nitrogen interacts with the ring
    Is this chem 4? :confused:
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    (Original post by marcus94)
    with NaOh it goes to [zn(OH)4]2- and they havent put an equation for when it reactions with ammonia at all



    theres not really anything to know about azo dyes other than how they are made... the ones with temperatures of 0-10 degrees is when you are making the azo dye and diazonium ion
    It does dissolve in excess with NH3 according to my revision guide and notes.
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    (Original post by ThisIsOurDecision)
    I don't think they really ask you about shapes except CuCl42- and CoCl42- (both tetrahedral) or Ni complexes/cisplatin (square planar).
    Thanks . Can I just ask what do we need to know about the chemistry of chromium and copper ?
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    (Original post by thelooby94)
    Is this chem 4? :confused:
    I think so, either way there has been a question on the strengths of bases asking u to put them in order
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    (Original post by Jukeboxing)
    It does dissolve in excess with NH3 according to my revision guide and notes.
    yeah it does, im not disputing that at all lol. Im just stating that it doesnt give the equation in both my text book or revision book
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    (Original post by Jukeboxing)
    It does dissolve in excess with NH3 according to my revision guide and notes.
    For clarity:
    Cu2+ will form a precipitate and redissolve in excess ammonia but NOT hydroxide
    Cr3+ will form a precipitate and redissolee in BOTH excess hydroxide and ammonia
    Ni2+ will form a precipitate and redissolve in excess ammonia but NOT hydroxide
    Zn2+ will form a precipitate and redissolee in BOTH excess hydroxide and ammonia
    these are the only ones you have to know i think when talking about redissolving
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    (Original post by marcus94)
    I think so, either way there has been a question on the strengths of bases asking u to put them in order
    unit 5 jan2012 (wierd paper as not many people take it!)
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    is it only the M2+ and M3+ aqueous ions that we have to learn the colour and observations???
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    (Original post by natninja)
    No, at least we've never been taught it and it's not on the syllabus
    It's synoptic so we do need to know it.
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    (Original post by Revent)
    I think you do.
    From the revision book I'm using you need to know:
    Its preparation and physical properties
    Reactions of the NH2 group as a base
    Reactions of the NH2 group with ethanoyl chloride
    Reactions of the NH2 group with Copper (II) ions
    Reactions of the NH2 group with Nitrous Acid
    The ring is activated the same way it is for phenol
    How would we do that?
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    (Original post by This Honest)
    How would we do that?
    as a Ligand .... dative covalent bond from the lone pair of electrons on the nitrogen...
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    (Original post by This Honest)
    How would we do that?
    Phenylamine with Cu2+ ions:

    • Ligand exchange
    • Green solution of phenylamine-Cu2+ complex forms
    • But there's not enough room for 4 Phenylamines



    so:


    [Cu(H2O)6]2+ + 2Phenylamine --->>> [Cu(Phenylamine)2(H20)4]2+ + 2H2O

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Updated: October 1, 2012
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