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Edexcel A2 Chemistry Exams -6CH04 (14th June) and 6CH05 (22nd June) Discussion Thread Watch

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    (Original post by Funky_Giraffe)
    Hey Don, do you have any idea how to work out which electrodes are used to measure standard electrode potentials? Sometimes it's the metal of the solution of ions you have, sometimes it's Pt?! How are we meant to know lol
    if a metal changes to an ion or vice versa then you use the metal, for example Fe2+ changes to Fe
    but if an ion changes to an ion, for ex Fe2+ to Fe3+ then you'd use platinum.
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    June 2014 IAL Q23 C PLEASE!
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    (Original post by imnoteinstein)
    if a metal changes to an ion or vice versa then you use the metal, for example Fe2+ changes to Fe
    but if an ion changes to an ion, for ex Fe2+ to Fe3+ then you'd use platinum.
    Hello, what are the chances someone would be able to post the mark scheme by tomorrow night? would be great if possible, thanks.
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    (Original post by payet27)
    Hello, what are the chances someone would be able to post the mark scheme by tomorrow night? would be great if possible, thanks.
    no clue :/ but theres alot of discussion on the thread itself so you sort of find out where you went wrong and stuff
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    (Original post by nishofficial)
    If someone could explain these to me I would be eternally grateful From the IAL Jan 16 so if you're currently doing it no need to look as I have marked it - just not understanding why the answers are what they are and need some explanation for them
    for Q3, its asking for least basic to most basic. phenylamine is least basic after water because the lone pair of electrons on nitrogen interact with delocalised e- system, making them 'less available' to accept a proton. butylamine is most basic as the alkyl groups are electron releasing, which makes the nitrogen 'more negative' which means its more likely to accept a proton.

    Q9) try writing out the half equation for dichromate to chromium (3+) and then you should see the electrons need to cancel out by the 1:3 ratio

    Q11) total of 3Cl, only the free Cl ions OUTSIDE the complex react with silver nitrate, so there must be only one cl in the complex itself

    Q12) not too sure but i thought it was because solid has one Fe, and the iron sulphate has 2Fe, so to balance the electrons in half eqs need to times by ratio of 2:1
    Q16) W and X are both addition polymers, derived from some kind of alkene hinted from the propen. Y and Z are the condensation polymers
    Q17) to do with the zwitterion and how neighbouring amino acids have ionic (electrostatic) attractions, i think?
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    I wish you all very best of luck with tomorrow's exam. Let's do this I look forward to discussing with you after exam.
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    Please can anyone help me with Q2c?
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  1. File Type: pdf 6CH05_01_que_20130122.pdf (480.1 KB, 55 views)
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    (Original post by Rahatara Sadique)
    Please can anyone help me with Q2c?
    there has to be one mole of ions and since the formula given has 2 Cr ions, divide the mass by 2
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    Help needed...

    The hydrolysis of a transition metal cation can be represented by the following equation:
    [M(H2O)6]N+ (aq) + H2O(l) reversible sign [M(H2O)5OH](n-1)+ (aq) +H3O+(aq)
    In this reaction:
    A the solvent H2O is acting as an acid by donating a proton to the metal cation
    B The pH of the solution will be lower if the value of n is 2 instead of 3
    C The equilibrium position lies further to the right if the value of n is 3 instead of 2
    D the oxidation state of the metal in the cation has decreased from n to (n-1)

    The answer is C but why??
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    (Original post by imnoteinstein)
    there has to be one mole of ions and since the formula given has 2 Cr ions, divide the mass by 2
    Thank you!
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    (Original post by Rahatara Sadique)
    Help needed...

    The hydrolysis of a transition metal cation can be represented by the following equation:
    [M(H2O)6]N+ (aq) + H2O(l) reversible sign [M(H2O)5OH](n-1)+ (aq) +H3O+(aq)
    In this reaction:
    A the solvent H2O is acting as an acid by donating a proton to the metal cation
    B The pH of the solution will be lower if the value of n is 2 instead of 3
    C The equilibrium position lies further to the right if the value of n is 3 instead of 2
    D the oxidation state of the metal in the cation has decreased from n to (n-1)

    The answer is C but why??
    If N is 3 then the transition metal cation will have a higher charge density,will therefore pull oxygen atoms more towards its side and and H+ are more easily to be lost so the extent of reaction will be higher and so the P.O.E will push more forward

    Has anyone gave up after solving Jan 2016 like literally IT'S SO FREAKING HARD

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    (Original post by Neha121101)
    for Q3, its asking for least basic to most basic. phenylamine is least basic after water because the lone pair of electrons on nitrogen interact with delocalised e- system, making them 'less available' to accept a proton. butylamine is most basic as the alkyl groups are electron releasing, which makes the nitrogen 'more negative' which means its more likely to accept a proton.

    Q9) try writing out the half equation for dichromate to chromium (3+) and then you should see the electrons need to cancel out by the 1:3 ratio

    Q11) total of 3Cl, only the free Cl ions OUTSIDE the complex react with silver nitrate, so there must be only one cl in the complex itself

    Q12) not too sure but i thought it was because solid has one Fe, and the iron sulphate has 2Fe, so to balance the electrons in half eqs need to times by ratio of 2:1
    Q16) W and X are both addition polymers, derived from some kind of alkene hinted from the propen. Y and Z are the condensation polymers
    Q17) to do with the zwitterion and how neighbouring amino acids have ionic (electrostatic) attractions, i think?
    Thank you so much, much appreciated at this late of a time!
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    (Original post by PlayerBB)
    If N is 3 then the transition metal cation will have a higher charge density,will therefore pull oxygen atoms more towards its side and and H+ are more easily to be lost so the extent of reaction will be higher and so the P.O.E will push more forward

    Has anyone gave up after solving Jan 2016 like literally IT'S SO FREAKING HARD

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    I understand about the charge density factor but i did not get the losing of H+ ions...
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    (Original post by tayloryeah)
    1. put the distalle of the impure product into a separating funnel
    2. wash with NaHCO3 to neutralise acid
    3. allow separation to occur
    4. run the organic liquid into a conical flask and place with anhydrous sodium sulphate
    (the drying agent must not react with the organic liquid and should be insoluble)
    5. decant the liquid into a distillation flask
    6. distill to obtain pure product
    For the 3rd step, you should add sodium chloride to help separate the layers
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    Good luck everyone! Hope everything goes well....
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    (Original post by Rahatara Sadique)
    I understand about the charge density factor but i did not get the losing of H+ ions...
    The bond become weeker between oxygen and H+ ions

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    I don't understand this someone please explain..


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    (Original post by tayloryeah)
    1. put the distalle of the impure product into a separating funnel
    2. wash with NaHCO3 to neutralise acid
    3. allow separation to occur
    4. run the organic liquid into a conical flask and place with anhydrous sodium sulphate
    (the drying agent must not react with the organic liquid and should be insoluble)
    5. decant the liquid into a distillation flask
    6. distill to obtain pure product
    Dies this actually come up in exams


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    (Original post by Adorable98)
    I don't understand this someone please explain..


    1. Basically you get the volumes of x and y at the highest point, by using the axis given. Then work out moles using concentration given in the question, this gives the molar ratio which gives the formula.
      For eg in the first picture x = 3x 0.05= 0.15
      Y= 7 x 0.05 = 0.35
      Therefore ratio is 1:2
      (0.15:0.35 isn't exactly 1:2 but you can round up/down to give single number)
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    (Original post by _H_V)
    1. Basically you get the volumes of x and y at the highest point, by using the axis given. Then work out moles using concentration given in the question, this gives the molar ratio which gives the formula.
      For eg in the first picture x = 3x 0.05= 0.15
      Y= 7 x 0.05 = 0.35
      Therefore ratio is 1:2
      (0.15:0.35 isn't exactly 1:2 but you can round up/down to give single number)
    I see but shouldn't it be 3.5 and 6.5?
 
 
 
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