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Solubility of p-block and d-block metals

  1. Jul 15, 2009 #1
    1. The problem statement, all variables and given/known data
    Show that,
    'In p-block and d-block metals their carbonates,sulphides and hydroxides are insoluble"

    I understand that all carbonates are insoluble(except the alkali metal carbonates),
    also that all sulphides are insoluble,but it's the solubilty of hydroxides that I'm finding difficult to prove,
    the hydroxides of Al,Zn,Sn as I know it are soluble in excess NaOH,so I don't understand how it's right to say all,p-block metal hydroxides are insoluble?
    I have the same problem with d-block metals(I'm considering the 3-d series only),
    my school notes tell me that all d-block metal hydroxides are soluble in excess NaOH.
    so I'm a bit confused here.
    I hope someone can tell me which is correct?
    the statement or my school notes?or have i just misunderstood the whole thing?
     
  2. jcsd
  3. Jul 15, 2009 #2

    Borek

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    Staff: Mentor

    Amphoterism seems to be a key word here...

    Hydroxide can be insoluble in water, but soluble in the presence of excess OH-.

    Note, that carbonates - that you have named as insoluble - are generally soluble in the strong acids. This is similar thing (even if completely different :wink:).

    --

    Honestly, I don't get the question - what does it mean "show that hydroxides are insoluble"? Will listing Ksp values suffice? Or do you have to produce precipitate of each one? Or is someone hoping you will show mathematically that presence of d orbitals means hydroxides must be solid? (in the last case looking for new proof of the Fermat's last theorem may be easier).

    --
     
  4. Jul 18, 2009 #3
    Thank you so much for responding,sir
    I'm sorry the question is not very clear.It was just something the teacher asked us in our discussion about a month ago and he was unable to finish explaining and I don't think it has anything to do with ksp values cause we were doing it under inorganic chemistry and its definitely not Fermut's theorem,don't know who or what his theorem is,but now I wonder if he was talking about the compounds' solubility in water only.
    I know that all sulphides and carbonates are insoluble in water and
    You've said,"hydroxides can be insoluble in water",so would it be correct to say that all the carbonates,sulphides and hydroxides formed by metals in the p-block and d-block are insoluble in water ?


    Thank you
     
  5. Jul 19, 2009 #4

    Borek

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    Staff: Mentor

    Don't sir me.

    Seems to me like you are mixing more things in one post than I can explain in one day :wink:

    Ksp stands for solubility product and is a way of expressing substance solubility. No idea what you mistook it for.

    That's only an approximation, but quite good one. You just have to remember that hydroxides of some metals can easily react with excess strong bases, creating salts (like sodium zincate for example).

    --
     
  6. Jul 19, 2009 #5
    I know what Ksp is.Its just that, we learnt it under Physical chemistry only after doing Inorganic chemistry,which is why I thought my sir wouldn't have thought of explaining it using Ksp values.So once again I'm sorry for not being very clear and Thankyou so much for the help,Borek :)
     
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