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    wot 6 mark question do u think goings to come up
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    I am certain that some sort of testing for ions will come up. It's such a massive section and they' we got loads of different subsections in it:/

    Testing for ions some of these I think may come up:
    Flame test
    Sodium hydroxide test
    Halide test
    Carbonate test
    Sulfate test
    (They might be absolute pricks and make you use knowledge about 3 or 4 or these tests to answer a question?:/)
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    (Original post by Nai18)
    Also, can anyone post key points about the period table from Newlands and Mendeleev please?

    Posted from TSR Mobile
    Newlands' Law of Octaves:
    - noticed every 8th element had similar properties so arranged elements in rows of seven according to atomic mass
    - BUT pattern broke down in 3rd row due to transition metals
    - Problems: groups contained elements which didn't have similar properties; he mixed up metals and non-metals; didn't leave any gaps for undiscovered elements

    Mendeleev:
    - arranged the known elements in order of atomic mass
    - left gaps to keep elements with similar proplerties in same columns (the groups)
    - he could predict properties of undiscovered elements from this

    Hope that helps, if you have any questions feel free to ask
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    Do thermosetting polymers have covalent bonds or intermolecular forces???

    Like what are the crosslinks and where are the forces???

    Thank youuu
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    (Original post by Muhammad Shafi)
    wot 6 mark question do u think goings to come up
    C3-
    Could be-
    describing a caliormetry/titration experiment
    Testing for ions
    Hard water/soft water and purification
    Haber process
    Explaining difference in reactivity of g1 &g7


    C2:
    Could be-
    Reasons why chlorine is gas at room temperature but solid with sodium
    Polymer
    (Doubt it would electrolysis)
    How metallic bonding/ionic bonding can
    Conduct
    Idk it's anyone's guess and with theb randomness of the biology ones.. It could be a comparison again? Just make sure you read all the sections especially the small ones !!!
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    (Original post by pollyy)
    Hi would anyone be able to explain to me how to do this question from the June 2013 C2 paper?

    Write the formula of ammonium sulfate using the ion formulas on the data sheet.

    The answer is (NH4)2SO4 but I can't work out how to get to that! Thank you!
    Yeah, so on the data sheet you're given that the formula for ammonium ions is NH4+ and the formula for sulfate ions is SO4(2-). To get the formula you have to balance the charges so that there is a neutral charge overall. As the sulfate ions have a charge of negative 2 but the ammonium ions have a charge of positive 1, you need two ammonium ions to balance the charge of the sulfate ions.

    Does that make sense? sorry i'm not very good at explaining!
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    do you think we would need to know the different rate of reaction experiments? eg the HCl and sodium thiosulphate one...
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    (Original post by XxRAEXx)
    C3-
    Could be-
    describing a caliormetry/titration experiment
    Testing for ions
    Hard water/soft water and purification
    Haber process
    Explaining difference in reactivity of g1 &g7


    C2:
    Could be-
    Reasons why chlorine is gas at room temperature but solid with sodium
    Polymer
    (Doubt it would electrolysis)
    How metallic bonding/ionic bonding can
    Conduct
    Idk it's anyone's guess and with theb randomness of the biology ones.. It could be a comparison again? Just make sure you read all the sections especially the small ones !!!
    Hi, I only do C2.
    I am sorry to ask this, but I am actually unsure as to why chlorine is gas at room temperature but solid with sodium???

    Could you explain to me please thankyou!!xxxxx
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    how can metallic bonding and ionic bonding conduct electricity???
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    (Original post by fabsafxo)
    Do thermosetting polymers have covalent bonds or intermolecular forces???

    Like what are the crosslinks and where are the forces???

    Thank youuu
    Thermosetting and thermosoftening polymers both have strong covalent bonds but thermosetting polymers have weak intermolecular forces whereas thermosoftening polymers have strong intermolecular forces (the strong intermolecular forces can also be called crosslinks). Covalent bonds are between the atoms themselves but intermolecular forces are between the different molecules of those atoms. As thermosetting polymers have strong intermolecular forces this makes them have a solid structure and won't soften when heated as the forces would need a lot of energy to overcome.
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    (Original post by pollyy)
    Yeah I think I mentioned the cost of the plant would be too high, but also a lot of energy is required to provide high pressures, so that in itself is expensive too!
    hi is that about C2 OR C3???
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    (Original post by spnlove)
    Thermosetting and thermosoftening polymers both have strong covalent bonds but thermosetting polymers have weak intermolecular forces whereas thermosoftening polymers have strong intermolecular forces (the strong intermolecular forces can also be called crosslinks). Covalent bonds are between the atoms themselves but intermolecular forces are between the different molecules of those atoms. As thermosetting polymers have strong intermolecular forces this makes them have a solid structure and won't soften when heated as the forces would need a lot of energy to overcome.
    OMDS!!
    Thankyou so much!!

    Life saver over 'ere;D xxx
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    Pedictions for c3 tomorrow?
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    (Original post by brozza981)
    Positive Ions Flame Test:
    PoP CaR BaG LiC SoY
    Potassium - Purple,
    Calcium - Red,
    Barium - Green,
    Lithium - Crimson,
    Sodium - Yellow!

    Please don't tell me that's C2
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    What kind of questions would come up for acids and bases? I'm still trying to get my head round it
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    Hi, I'm sorry to ask this but can someone go through the Titration, Halide, Sulfate and Sodium Hydroxide tests please. I'm really confused with them!
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    (Original post by mghp)
    Please don't tell me that's C2
    It's c3
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    (Original post by spnlove)
    Yeah, so on the data sheet you're given that the formula for ammonium ions is NH4+ and the formula for sulfate ions is SO4(2-). To get the formula you have to balance the charges so that there is a neutral charge overall. As the sulfate ions have a charge of negative 2 but the ammonium ions have a charge of positive 1, you need two ammonium ions to balance the charge of the sulfate ions.

    Does that make sense? sorry i'm not very good at explaining!
    Yes it does! Thank you, I think I just got confused because I always think of ammonia as NH3, but I understand now Thanks!
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    (Original post by zc555)
    Hi, I'm sorry to ask this but can someone go through the Titration, Halide, Sulfate and Sodium Hydroxide tests please. I'm really confused with them!
    Titration: Is used to find how much acid is needed to neutralise an alkali (or vice versa) which is then used to calculate an unknown concentration.
    Did you want help with the calculation or the titration method?

    As for the ion tests; to test for halides, add dilute nitric acid (not HCL as that contains chlorine which is a halide!) then add silver nitrate solution, and use the colour of the precipitate to distinguish between halides:
    Chlorides- white precipitate
    Bromides- cream precipitate
    Iodides- yellow precipitates

    Sulfate test: add dilute HCL then barium chloride solution, if a WHITE precipitate is formed, then the substance is a sulfate!

    Sodium Hydroxide test (for metal ions): Add NaOH, then use colour of precipitate to distinguish-
    Iron (II)- Green precipitate
    Iron (III)- Reddish brown precipitate
    Copper (II)- Light blue precipitate
    Magnesium, Calcium and Aluminium ALL form white precipitates, but aluminium ions dissolve in excess NaOH into a colourless solution, and calcium ions can be distinguished through the flame test (red flame).

    Hope this helps and I can try and help with titration too!
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    This is what I think I know about polymers; is it correct?

    Thermosoftening - Weak intermolecular forces between chains make it easy to seperate chains and this results in them having a low melting/boiling points so they can be melted and re-moulded.

    Thermosetting - Strong covalent bonds between chains mean that chains are hard to seperate and therefore they have high melting/boiling points because large amounts of energy are required to break chains. Can't be melted and re-moulded

    Is this correct? Anything to add? Thanks.
 
 
 
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