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Edexcel IAL Chemistry Unit 01 - 26th of May, 2017 Watch

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    (Original post by zooshan)
    maybe this will help?
    thank you so much
    could you please help me with this question:
    Which equation represents the reaction for which the enthalpy change, H, is the mean bond energy of the C-F bond?
    A CF4 (g) ------- C(g) + 4F(g)
    B ¼CF4 (g) --------¼C(g) + F(g)
    C C(g) + 4F(g) --------- CF4 (g)
    D ¼C(g) + F(g) -----------¼CF4 (g)
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    (Original post by mr.holmes)
    thank you so much
    could you please help me with this question:
    Which equation represents the reaction for which the enthalpy change, H, is the mean bond energy of the C-F bond?
    A CF4 (g) ------- C(g) + 4F(g)
    B ¼CF4 (g) --------¼C(g) + F(g)
    C C(g) + 4F(g) --------- CF4 (g)
    D ¼C(g) + F(g) -----------¼CF4 (g)
    i think its B..as everything has to be 1:1 ratio.. but i m not very sure.. sorry...
    can u tell me which year this paper is?
    whats the mark scheme answer?
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    (Original post by mr.holmes)
    thank you so much
    could you please help me with this question:
    Which equation represents the reaction for which the enthalpy change, H, is the mean bond energy of the C-F bond?
    A CF4 (g) ------- C(g) + 4F(g)
    B ¼CF4 (g) --------¼C(g) + F(g)
    C C(g) + 4F(g) --------- CF4 (g)
    D ¼C(g) + F(g) -----------¼CF4 (g)
    Is it A
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    (Original post by neelc21)
    Is it A
    but then its not the same mole ratio right?
    how is it so? can u please explain... :/
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    (Original post by zooshan)
    i think its B..as everything has to be 1:1 ratio.. but i m not very sure.. sorry...
    can u tell me which year this paper is?
    whats the mark scheme answer?
    it is May 2013
    question 17
    and the answer is B
    but if it is 1:1 why is it 1/4 of the carbon?
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    (Original post by mr.holmes)
    it is May 2013
    question 17
    and the answer is B
    but if it is 1:1 why is it 1/4 of the carbon?
    there are 4 fluorine..
    it does say that the bond enthalpy is a mean of all the bonds..
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    (Original post by zooshan)
    there are 4 fluorine..
    it does say that the bond enthalpy is a mean of all the bonds..
    if you can explain more?
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    (Original post by zooshan)
    but then its not the same mole ratio right?
    how is it so? can u please explain... :/
    I dont know, i just guessed
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    (Original post by mr.holmes)
    if you can explain more?
    makes sense?
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    (Original post by neelc21)
    I dont know, i just guessed
    oh.. okay..
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    Anyone got some last minute short revision notes, would be really helpful.
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    (Original post by waow)
    Anyone got some last minute short revision notes, would be really helpful.
    https://chemrevise.org/3-edexcel-revision-guides/
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    :rave:BEST OF LUCK FOR YOUR EXAM TODAY, EVERYONE!!! :rave:




    I couldn't tag u guys, so I'm quoting you:
    1. (Original post by Aadha24)
      x
    2. (Original post by waow)
      x


    I'm extremely sorry if I had missed out anyone
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    (Original post by raai ahamed)
    ok fine sis!!!!
    Don't be angry with me bro
    You haven't edited it yet
    But it's ok
    I don't think anyone would notice
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    (Original post by mr.holmes)
    thank you so much
    could you please help me with this question:
    Which equation represents the reaction for which the enthalpy change, H, is the mean bond energy of the C-F bond?
    A CF4 (g) ------- C(g) + 4F(g)
    B ¼CF4 (g) --------¼C(g) + F(g)
    C C(g) + 4F(g) --------- CF4 (g)
    D ¼C(g) + F(g) -----------¼CF4 (g)

    If they had asked an equation to represent 4deltaH, it'd be A
    However they asked an equation to represent deltaH.
    Answer is B
    Carbon has already gone under atomization, so its mole ratio really don't matter.
    If you look at the enthalpy change of atomization of fluorine,
    1/4F4(g) --------> F(g) deltaH
    F4(g) ------------> 4F (g) 4delta H (x4 all)

    Definition of (standard) enthalpy change of atomization
    The standard atomisation enthalpy is the enthalpy change when 1 mole of gaseous atoms is formed from the element in its standard state (under standard conditions).
    Can't be C or D as bond energy involves the breaking of bonds, which is an endothermic process.
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    Exam starts in 1 and a half hour for me.. best of luck to everyone!!!
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    Guys how was the paper.. Just finished mine
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    (Original post by mandax_25)
    Guys how was the paper.. Just finished mine
    How was yours?
    Was the paper just like how you expected?
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    (Original post by CaptainJackFail)
    Exam starts in 1 and a half hour for me.. best of luck to everyone!!!
    Are you from the UK?
    I guess sri lankans might have finished their exam coz it's started at 10 AM I guess

    (Original post by Aadha24)
    x
    Have you finished ur exam? How was it? Easy?
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    (Original post by 01.ash)
    Thank you
    It was okay, I hope the grade boundaries won't go up.
    Hbu?
    Hmmm, if the paper was easy for most of the candidates, the grade boundaries would probably go up
    And the grade boundaries are chosen after the examiners finish marking all of the candidates' papers
    Unfortunately, I changed my decision, so I'm doing exams in October, coz I needed more time for exam preparation as I'm self-teaching
 
 
 
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