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    (Original post by Luke0011)
    I think this is due to the arrangement of ions, but we dont need to know that at our level
    Ah okay, I won't panic too much then! Cheers
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    (Original post by GoodOl'CharlieB)
    I had the same problem...see quote 283 for the answer.
    This helps to explain it really well
    hahaha thanks, it did explain well - silly me for not looking up.
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    okay another chemistry qualm...okay when is [Al(OH4)]- produced instead of [Al(OH6)]^3- produced. In Jan'11 in the equations bit the mark scheme said [Al(OH6)]^3- but all of my textbooks say [Al(OH4)]- forms in excess OH- ....so which one is correct..? Are both? If not, what conditions change which one is formed?
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    (Original post by Harry Potter's sidekick)
    okay another chemistry qualm...okay when is [Al(OH4)]- produced instead of [Al(OH6)]^3- produced. In Jan'11 in the equations bit the mark scheme said [Al(OH6)]^3- but all of my textbooks say [Al(OH4)]- forms in excess OH- ....so which one is correct..? Are both? If not, what conditions change which one is formed?
    In Excess NaOH
    4OH- + [Al(H20)6]3+ -> [Al(OH)4]- + 6H20

    The [Al(OH)4]- is the right one
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    in terms of the metal ions we need to know about in aqueous solution, is it chromium, iron, copper cobalt and aluminum?
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    (Original post by Luke0011)
    In Excess NaOH
    4OH- + [Al(H20)6]3+ -> [Al(OH)4]- + 6H20

    The [Al(OH)4]- is the right one
    but have you done the jan'11 paper - check out question 6B...it's [Al(OH)6]^3- on there...
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    (Original post by Harry Potter's sidekick)
    but have you done the jan'11 paper - check out question 6B...it's [Al(OH)6]^3- on there...
    Mark schemes wrong? Unless i'm mistaken
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    (Original post by Harry Potter's sidekick)
    but have you done the jan'11 paper - check out question 6B...it's [Al(OH)6]^3- on there...
    It actually says you can have a range of numbers of OH- from like 4 to 6 I think..
    Both are correct.
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    (Original post by Harry Potter's sidekick)
    but have you done the jan'11 paper - check out question 6B...it's [Al(OH)6]^3- on there...
    I know! We had the same realisation in class when marking that past paper... The mark scheme seemed to prefer [Al(OH)6]^3-... I'm not sure why because the don't mention it in the book at all. :confused: CGP revision guide seems to prefer [Al(OH)4]- aswell, so I think i'm just going to put that down if it comes up. My teacher rang the exam board to ask about this... as you can imagine AQA weren't much help and said put it to them in writing and they'll get back asap. Hmmm.

    Hope they do before the exam :rolleyes:
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    (Original post by Harry Potter's sidekick)
    but have you done the jan'11 paper - check out question 6B...it's [Al(OH)6]^3- on there...
    Oh, it does allow [Al(OH)4]- though!
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    Does anyone know a quick and easy way to remember what states things will be in under standard conditions? For example Ca is always solid and F2 is always gas in their standard states.
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    It might already have been asked (sorry I haven't got time to read the whole thread) but has anyone got any tips on how I can learn all the transition metals equations and observations before the exam on Friday??? Yes, I know I'm leaving it till a bit late, but I'm getting a little desperate now!!
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    (Original post by Luke0011)
    Oh, it does allow [Al(OH)4]- though!
    Thank goodness! I was getting worried then
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    (Original post by BethBeth)
    Thank goodness! I was getting worried then
    Same haha! They also allow [Al(OH)5]2- haha!
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    (Original post by OhNo_23)
    I got confused over this also. Its because it works a bit like a chain reaction. The V2+ becomes the V3+ first, then that is oxidised again to form the VO(2+), and then this in turn is further oxidised to form the final (VO2)+.
    It's a bit of nasty question but once you see it its easy. Hope this makes sense anyways!
    yeah, i noticed that it was like a chain too. but does this apply to every question in this form or only vanadium due to its various oxidation states?
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    (Original post by Luke0011)
    Same haha! They also allow [Al(OH)5]2- haha!
    AQA can't seem to make up their minds sometime At least I can stop worrying about that one and worry about the rest of Unit 5! :eek:
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    (Original post by teddyWS)
    yeah, i noticed that it was like a chain too. but does this apply to every question in this form or only vanadium due to its various oxidation states?
    Could maybe use Chromium too, as:

    (Cr2O7)2-

    Cr3+

    Cr2+
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    (Original post by Sheldon)
    hey guys just thought I would post a list of some TM reactions that I made
    If you find them useful I have other notes I made like that for periodicity and some other parts.
    Hi just noticed slight error in your TM reactions, instead of 2H20 should be 3H2O. other than its brilliant stuff,keep up the good work!

    [M(H?O)?]³+ +3OH¯ ?[M(H?O)?(OH)?](s) +2H?O
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    (Original post by GoodOl'CharlieB)
    Firstly thanks again it makes so much sense now:five::excited: ...the MS was so confusing :confused:
    Secondly, have u ever thought of going into teaching?
    And thirdly , I now have cravings for cake lol :cake:
    Thanks again, you explain things really well

    Btw 1 more thing and I promise I will go away, what are the advantages and disadvantages of the different types of batteries?
    Haha no problem, I also kind of want cake now

    Actually I'm hoping to teach at university level

    The batteries stuff is where I become shaky as it's all wishy washy, but that makes it good for me to explain it I suppose!

    Non-rechargable cells:

    + Cheaper
    + Lower toxicity as they are less likely to contain lead and cadmium so less hazardous in landfills.
    + More power per cell so can be used in devices that need a lot of power
    + Longer lifetime before needs to be chucked.

    - Have to be replaced when they run out
    - Waste more resources as they aren't reusable.
    - Expensive in the long run

    Rechargable Cells:

    + Reusable
    + Saves money in the long run
    + Saves on resources as they don't have to be replaced.

    - Shorter lifetime before recharging is needed.
    - Expensive
    - Higher toxicity such as lead and cadmium
    - Less power so can only be used for small devices.
    - Needs to be recharged (long intermediates between uses)

    Hydrogen Fuel Cells:

    + Don't need to recharge (short intermediate time between uses)
    + Only waste is water (no CO2 or toxins)

    - Energy needed to produce Hydrogen gas which is usually done by electrolysis which uses electricity generated from fossil fuels (so therefore not carbon neutral).
    - Hydrogen is flammable so storage and transport is difficult and/or costly.
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    Ok, I should probably know this already, but I just wanted some clarification on electron shells.

    So when you fill up the electron shells, you fill up 4s first and then move onto 3d? (apart from the exceptions Cr and Cu) Yet when you write down the electron configuration, you write 3d first and then 4s?

    Also when an electron is removed to make an ion, is it removed from the 4s shell or the 3d shell?
 
 
 
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