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Equilibria, Energetics and Elements (F325) - June 2011 Exam. watch

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    (Original post by TsunKit)
    Could someone explain to me why the second electron affinity is +'ve. I think it was something to do with removing a negative charge?
    It'd be nice to have someone clarify though
    Sorry i meant to say endothermic.
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    (Original post by HHPP)
    A lot of energy needed means it's endothermic.
    yes sorry, slip of the keyboard.
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    (Original post by Perky perks)
    so which one is it that is like a born haber cycle but uses hydration and solution instead of atomisation and ionisation??
    you make a born haber cycle to find the enthalpy of solution by using the lattice enthalpy and the hydration enthalpys.
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    (Original post by susan23)
    wtf is half neutralisation :lolwut:
    When you have say 1 mole of acid and half a mole of base, it then leaves you with half a mole of acid, half mole of it's conjugate base and water, it is a method for creating buffer solutions
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    (Original post by SteveScott)
    It can't hurt, just rememberit's used in detergents, it's a pretty general answer to 'what is this chemical used for' in chemistry exams
    Ok, though i doubt i can really fit anything else in my ridiculously tiny brain right now :sigh:

    (Original post by susan23)
    wtf is half neutralisation :lolwut:
    This :banghead:
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    Lone pairs on ligands when drawing complexes?????
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    (Original post by SteveScott)
    It can't hurt, just rememberit's used in detergents, it's a pretty general answer to 'what is this chemical used for' in chemistry exams
    Its also used as a chelating agent.
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    (Original post by mandn)
    When you have say 1 mole of acid and half a mole of base, it then leaves you with half a mole of acid, half mole of it's conjugate base and water, it is a method for creating buffer solutions
    WHAT THE ****!!! I DIDNT KNOW THAT!! looooooooooooooooooool

    so what happens to the other half of the acid then??? reacts to form water?
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    (Original post by INeedToRevise)
    Lone pairs on ligands when drawing complexes?????
    Don't think so....
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    what is the tetrahedral complex and what are the bond angles?
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    I'm confused, when deltaG<0, the reaction is spontaneous and hence stable, but in the mark scheme of the jan 11 paper it says deltaG>0 is stable. Why is this?
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    (Original post by INeedToRevise)
    Lone pairs on ligands when drawing complexes?????
    yes I do...I dont htink theres anything wrong with it
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    Question 1A iii on the specimen paper

    can someone tell me WHY they've divided 1x10-12 by 4?

    pretty please
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    (Original post by mandn)
    At half neutralisation [A-]=[HA] so Ka=[H+] so pKa=pH BUT ONLY FOR HALF NEUTRALISATION
    ^^ do we need to know that??
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    Reactions involving Complex ions:

    - Percipitation
    - Substitution
    - Redox

    Any more?
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    (Original post by 123trident)
    I'm confused, when deltaG>0, the reaction is spontaneous and hence stable, but in the mark scheme of the jan 11 paper it says deltaG<0 is stable. Why is this?
    nooooooooooooooooo!!!

    delta G has to be below 0 so negative value for reaction to be feasible and spontaneous!!

    OK ALWAYS REMEMbER THIS!!!
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    (Original post by KnuckleheadNinja)
    Question 1A iii on the specimen paper

    can someone tell me WHY they've divided 1x10-12 by 4?

    pretty please
    THIS!
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    (Original post by susan23)
    WHAT THE ****!!! I DIDNT KNOW THAT!! looooooooooooooooooool

    so what happens to the other half of the acid then??? reacts to form water?
    half a mole of acid reacts with half a mole of a base this then forms it's conjugate base and water, but when using a whole mole of acid and half a mole of base half a mole of acid doesn't react and forms a buffer with the half mole of it's conjugate base
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    Can someone plz clarify the lone pairs bit either way? As far as i remember you're not expected to draw them, in the past papers? xD
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    (Original post by susan23)
    nooooooooooooooooo!!!

    delta G has to be below 0 so negative value for reaction to be feasible and spontaneous!!

    OK ALWAYS REMEMbER THIS!!!
    Susan did you get my message earlier?
 
 
 
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