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    (Original post by mulac1)
    we do not need to know any knowledge of batteries/cells other than the hydrogen oxygen fuel cell. We also need to be able to talk about the relative advantages and disadvantages of the hydrogen-oxygen fuel cell.

    Does anyone know the definition for 'enthalpy of atomisation of a compound'
    Enthalpy change where one mole of gaseous atoms are formed from its elements in its standard state, under standard condition e.g. 1/2Cl2(g) --> Clg

    That's what I know it as anyway.
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    (Original post by crc290)
    The question is actually:
    "Calculate the temperature ABOVE WHICH the reaction between hydrogen and oxygen to form gaseous water is not feasible."
    I'm being really dumb, but its the wording of the question that confused lol Can't get my head round it lol
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    (Original post by mulac1)
    we do not need to know any knowledge of batteries/cells other than the hydrogen oxygen fuel cell. We also need to be able to talk about the relative advantages and disadvantages of the hydrogen-oxygen fuel cell.

    Does anyone know the definition for 'enthalpy of atomisation of a compound'
    The standard enthalpy change which accompanies the formation of 1 mole of gaseous atoms from its element in its standard state and under standard conditions
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    (Original post by amelia95)
    The standard enthalpy change which accompanies the formation of 1 mole of gaseous atoms from its element in its standard state and under standard conditions
    yes - that is the definition of the standard enthalpy of atomisation of an element, but not of a compound. I was wondering if anyone has any textbook definitions (since its on the spec. but not in the textbook)
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    (Original post by Kev.1995)
    Yes
    Cheers.
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    What is there to know about the hydrogen fuel cell?! Also, how do I know when to multiply the enthalpy of atomisation for a diatomic molecule, and when not to?
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    Went through the Jan 13 paper I did as a mock and still can't believe she docked me like 5 marks because my g's looked like s's. :rolleyes:

    Did make some pretty stupid errors on that paper though
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    (Original post by Med_me)
    What is there to know about the hydrogen fuel cell?! Also, how do I know when to multiply the enthalpy of atomisation for a diatomic molecule, and when not to?
    In the specimen paper, you needed to the the half equations under alkali conditions for it (and hence overall).
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    WHAT COLOUR WILL DEFINATELY GET ME MARKS FOR HEXAAQUACHROMIUM??? green solution or ruby
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    (Original post by mulac1)
    yes - that is the definition of the standard enthalpy of atomisation of an element, but not of a compound. I was wondering if anyone has any textbook definitions (since its on the spec. but not in the textbook)
    The Enthalpy of atomisation of a compound is the enthalpy change when 1 mole of a compound in its standard state is converted to gaseous atoms, e.g NaCl(s) ----> Na(g)+Cl(g)
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    Can someone please help me with January 2011 the last question. I can do the calculation but I do not know how to balance the equation...It would be a big help.
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    (Original post by crc290)
    It could also be H2O2 + 2H+ + 2e- \rightarrow 2H2O, just depends what the question specifies
    There are so many, there is also this:
    H2O2 --> O2 + 2H+ + 2e- (although this is when hydrogen peroxide is acting as a reducing agent)
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    (Original post by JenniS)
    WHAT COLOUR WILL DEFINATELY GET ME MARKS FOR HEXAAQUACHROMIUM??? green solution or ruby
    both but prefered purple i think ;p i still say green though ;p cuz all the Cr3+ ions are green(apart from [Cr(NH3)6]3+ which is purple)
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    Can someone HELP ME with question 3b and c in the jan 2010 paper- im really stuck on the hydrogen fuel cell. Thanks
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    (Original post by JenniS)
    WHAT COLOUR WILL DEFINATELY GET ME MARKS FOR HEXAAQUACHROMIUM??? green solution or ruby
    hmm good question - I think it depends on the phrasing of the question. Firstly, they'll always accept either..

    but if it says 'what is the colour of the hexaaquachromium(III) ion / [Cr(H2O)6], then I'd put ruby.

    If the question asked for the colour of chromium(III) ions in aqueous solution, then I'd say green.
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    (Original post by cuckoo99)
    The Enthalpy of atomisation of a compound is the enthalpy change when 1 mole of a compound in its standard state is converted to gaseous atoms, e.g NaCl(s) ----> Na(g)+Cl(g)
    thank you - that is exactly what I was looking for!
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    (Original post by Atz23)
    Can someone please help me with January 2011 the last question. I can do the calculation but I do not know how to balance the equation...It would be a big help.
    2MnO4– + 6H+ + 5H2O2 ----> 2Mn2+ + 8H2O + 5O2
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    (Original post by Melissa.S.)
    I'm being really dumb, but its the wording of the question that confused lol Can't get my head round it lol
    At a certain temperature ΔG = 0. Above that temperature, the reaction will not be feasible. The question is asking you to work out that temperature
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    Definitions of ligand, bidentate, monodentate and complex ion anyone?
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    (Original post by cuckoo99)
    both but prefered purple i think ;p i still say green though ;p cuz all the Cr3+ ions are green(apart from [Cr(NH3)6]3+ which is purple)
    (Original post by mulac1)
    hmm good question - I think it depends on the phrasing of the question. Firstly, they'll always accept either..

    but if it says 'what is the colour of the hexaaquachromium(III) ion / [Cr(H2O)6], then I'd put ruby.

    If the question asked for the colour of chromium(III) ions in aqueous solution, then I'd say green.
    thanks guys, I always go for green but my friend was like ahh its ruby, so yeh I wreckon if we're writing equations where its in solution I'll go for green.
    On the jan 2011 paper they accepted ruby/purple/green/red-blue/violet so I think we're all fine
 
 
 
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