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    Is Chemy five tough
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    Can someone help me understand this question please?
    "Explain why the hydration of the fluoride ion is more negative than the hydration enthalpy of the chloride ion?
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    (Original post by cheesypuff)
    Is Chemy five tough
    I found Chem5 easier than Chem4. But maybe that's just because I'm still in the process of revising for it!
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    (Original post by Quarky)
    Can someone help me understand this question please?
    "Explain why the hydration of the fluoride ion is more negative than the hydration enthalpy of the chloride ion?
    Fluoride ions are smaller than chloride ions, and as such have a greater charge density. This means that the negative charge on a fluoride ion attracts the δ+ hydrogen on a water molecule more strongly than that of a chloride ion. Hence, more negative enthalpy of hydration.
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    (Original post by Tullia)
    Fluoride ions are smaller than chloride ions, and as such have a greater charge density. This means that the negative charge on a fluoride ion attracts the δ+ hydrogen on a water molecule more strongly than that of a chloride ion. Hence, more negative enthalpy of hydration.
    Ahh I see, cheers
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    (Original post by Hamzi)

    Its on q4 on the June 2011 paper

    Here is the link to the paper:
    http://filestore.aqa.org.uk/subjects...W-QP-JUN11.PDF
    hi,
    this question talks about observations of magnesium and sulfur burning in oxygen.
    for magnesium we would observe a vigorous reaction with a bright white flame and white fumes
    for sulfur we would observe a blue flame and a choking gas

    me
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    Hello
    does anyone know what u will se when caoh2 reacts with water and when Caso4 adds to water
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    (Original post by Hamzi)
    I guess you do because if they give you all the observations for the other period 3 elements with oxygen in the text book then why did they just skip observations for silicon.

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    Because it practically doesn't even happen..or infact it is just too slow.
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    Can anyone tell me why iron (II) needs different amounts of ethanedioate than Cu2+ on titration?
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    HELP! Has anyone found an easy way of memorizing the observations of Acid-Base substitutions of the metal ions Fe(2+) Fe(3+) Co Cu Al Cr(3+) ?

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    (Original post by popnit)
    You don't need to know this, it's not even mentioned in the nelson thorne textbook

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    Actually if you check part 3.5.2 of the Chem specification it says you how period the elements react with oxygen, limited to the formation of Na Mg Al Si P and S oxides. But you DO NOT need to know how Al203 and SiO2 reacts with WATER as they are INSOLUBLE
    SIZE=1]Posted from TSR Mobile[/SIZE]
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    (Original post by Ren_9)
    Actually if you check part 3.5.2 of the Chem specification it says you how period the elements react with oxygen, limited to the formation of Na Mg Al Si P and S oxides. But you DO NOT need to know how Al203 and SiO2 reacts with WATER as they are INSOLUBLE
    SIZE=1]Posted from TSR Mobile[/SIZE]
    Well spotted!
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    (Original post by Lucianaaaa)
    Can anyone tell me why iron (II) needs different amounts of ethanedioate than Cu2+ on titration?
    Are you comparing why Fe2+ and Fe3+ need different amounts and Cu2+ Cu+ doesn't?
    Not sure but it might be connected to the density charge on each ion that may cause an already slightly acidic soln. Strong coordinate bonds and weak O-H bonds that cause H to 'fall off'

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    Electrochemical cells is nowhere near as bad as I thought it would be! Still haven't fully memorised Transiton Metal complexes though :/
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    (Original post by Xiomara)
    Electrochemical cells is nowhere near as bad as I thought it would be! Still haven't fully memorised Transiton Metal complexes though :/
    Strangely for me, Transition metals are my favourite topic. I'm scared to look at redox equilibria and the rest of electrochemistry though :lol:
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    Has anyone done the isa and if yes, how was it??? Difficult?
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    (Original post by erniiee)
    Strangely for me, Transition metals are my favourite topic. I'm scared to look at redox equilibria and the rest of electrochemistry though :lol:
    I found Unit 5 so so much easier than unit 4. I don't know why.
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    I hate this unit
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    (Original post by Mocking_bird)
    I hate this unit
    You and me both.
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    (Original post by frogs r everywhere)
    I found Unit 5 so so much easier than unit 4. I don't know why.
    I feel the same way, the only thing is that it's synoptic so in the exam they could ask you about anything from AS and also unit4

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