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    Can someone help me with an entropy question. I keep messing up the units

    http://filestore.aqa.org.uk/subjects...5-QP-JUN13.PDF

    3cii
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    (Original post by Super199)
    Can someone help me with an entropy question. I keep messing up the units

    http://filestore.aqa.org.uk/subjects...5-QP-JUN13.PDF

    3cii
    just divide your deltaS by 1000 and the units for the answer is kj k-1 mol-1 ?
    deltaG=deltaH-TdeltaS
    0=deltaH-TdeltaS
    deltaH=5440(your deltaS value/1000)
    i think it's like this?
    good luck tmr tho im really nervous as well


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    A sample of solid chromium(III) hydroxide displays amphoteric character when treatedseparately with dilute hydrochloric acid and with dilute aqueous sodium hydroxide.Write an ionic equation for each of these reactions. Include the formula of eachcomplex ion formed.Describe the changes that you would observe in each reaction

    I lost the two marks as it wanted the ionic equations? i really can't do them any one help urgently pleasE

    Please 2nd time posting!


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    (Original post by Boundless_x)
    It was Jan 11 q 6b
    sorry late reply. In the notes section it says

    "Allow formation of [Al(H2O)6–x(OH)x](x–3) where x=4,5,6"

    Al(OH)4 - is the same as Al(OH)4(H2O)2. So you can do other ones. I would stick with the mark scheme representation to be safe
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    http://filestore.aqa.org.uk/subjects...W-QP-JAN11.PDF

    1b quickly please

    Why do we divide the chlorine one by two?

    Is it because of the formation of Nacl?
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    In a conventional cell representation do aqueous substances and liquids need to be separated by a phase boundary?
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    (Original post by SirRaza97)
    sorry late reply. In the notes section it says

    "Allow formation of [Al(H2O)6–x(OH)x](x–3) where x=4,5,6"

    Al(OH)4 - is the same as Al(OH)4(H2O)2. So you can do other ones. I would stick with the mark scheme representation to be safe

    Thank you!
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    (Original post by ahsan_ijaz)
    A sample of solid chromium(III) hydroxide displays amphoteric character when treatedseparately with dilute hydrochloric acid and with dilute aqueous sodium hydroxide.Write an ionic equation for each of these reactions. Include the formula of eachcomplex ion formed.Describe the changes that you would observe in each reaction

    I lost the two marks as it wanted the ionic equations? i really can't do them any one help urgently pleasE

    Please 2nd time posting!


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    It's a bit too late now... Learn the ones in the markscheme

    Cr(H2O)3(OH)3 + 3H+ -> [Cr(H2O)6]3+

    Al(H2O)3(OH)3 + OH- -> [Al(OH)4]- + 3H2O

    Ionic equation just means separate all aqueous reactants and products into ions and cancel any of the same ions on both sides of the equation.

    (Original post by Boundless_x)
    In a conventional cell representation do aqueous substances and liquids need to be separated by a phase boundary?
    Use a comma to be on the safe side but I think they allow | instead.
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    (Original post by Super199)
    http://filestore.aqa.org.uk/subjects...W-QP-JAN11.PDF

    1b quickly please

    Why do we divide the chlorine one by two?

    Is it because of the formation of Nacl?
    That't not the atomisation enthalpy bur the bond dissociation enthalpy. For Nacl formation, you only need one Cl atom but that equation gives you 2 so you half it.
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    Any predictions for tomorrow, what Ligand reactions do you think will come up?
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    well after staying awake the whole night i think iv safely re learnt all topics time to cram few papers in before the exam, any one know hard papers?
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    (Original post by shamk123)
    well after staying awake the whole night i think iv safely re learnt all topics time to cram few papers in before the exam, any one know hard papers?
    Same.. couldn't sleep so I watched Argentina vs USA and did a bit of revision

    June 13 had low grade boundaries so you could try that
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    what does it mean when it says write the equation when the cell discharges?
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    (Original post by Cakey_101)
    what does it mean when it says write the equation when the cell discharges?
    When it's giving out charge- discharge therefore you write the equation how it is..
    When it's recharging flip the equation...
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    When you got 6 hours sleep and youve got chem 5 n chill in 2 hours :'( :eek:
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    (Original post by haj101)
    When it's giving out charge- discharge therefore you write the equation how it is..
    When it's recharging flip the equation...
    Wouldn't they be the same thing?
    To work out the overall equation you use the anti-clockwise rule right?
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    (Original post by haj101)
    When it's giving out charge- discharge therefore you write the equation how it is..
    When it's recharging flip the equation...
    Actually i think i know what you mean!
    So discharging is when the cell is being used and recharging is the reverse when its being recharged.
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    (Original post by Cakey_101)
    Actually i think i know what you mean!
    So discharging is when the cell is being used and recharging is the reverse when its being recharged.
    Exactly
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    Good luck everyone!
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    Good luck to everyone!
 
 
 
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