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Edexcel - Chemistry Unit 2 - 4 June 2013 watch

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    (Original post by James A)
    Who told you that sulfur is +1 then?

    It depends what the question tells you tbh.

    (Original post by Big-Daddy)
    What nonsense. Na has oxidation state +1, H has oxidation state +1, S has oxidation state -2. HS- is a well-known anion; imagine having H2S in solution, it dissociates once and what do you get? HS-. This isn't some mystical compound we're dealing with. It's very standard.

    Group 1 and (I think) Group 2 will always have oxidation state +1 and +2 respectively. That's the first rule of deciding oxidation states, and the whole system of working them out is a theoretical game rather than based on reality so there's no point debating it. So let me say it again: Group 1 and (I think) Group 2 will always have oxidation state +1 and +2 respectively.

    Sorry the question asked what sulphur was, that's why I got it wrong. I panicked because I thought obviously sodium would be +1, hydrogen would be +1 and sulphur would be -2, but I answered +1 for what I thought was a question on sodium that was actually on sulphur then I was shocked when the mark scheme said the answer was -2.

    Classic RTQ here.
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    so in permanent dipole interactions, is that only due to electronegativity differences between atoms in a covalent bond?
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    (Original post by adi19956)
    Classic RTQ here.
    Or as my Chemistry teacher scribbles over our papers: "RTFQ".

    I'll leave it down to you to determine what the 'F' stands for.
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    (Original post by Maximan12)
    B as the OH will be able to be broken off to form a peak at mass of O + H (16+1) in the secondary alcohol the OH is not at one end and cannot be removed to form this peak
    Wrong. It's D.
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    (Original post by tahadamani)
    so in permanent dipole interactions, is that only due to electronegativity differences between atoms in a covalent bond?
    Right.
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    (Original post by maryam1996)
    (Original post by HarryMWilliams)
    A bond isn't "electronegative" at all, it is polar. The C-Br and C-I bonds are polar due to the presence of an electronegative element. Iodine is far less electronegative than Bromine, hence that polar is far less polar.

    As you go down the group, the size of the cation increases in size, but the charge remains the same (+2), hence the cation is less able to polarise and as a result distort the negative anion (carbonate/sulfate ion). Less distortion leads to increased thermal stability.
    Thank you so much!
    No worries, glad to have helped.
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    (Original post by posthumus)
    I look back on that paper like " How on earth did I get a U :ashamed2: "
    Got 20/20 marks for the first section.

    I'm gonna have a shower now, so hopefully it will cool me down a little, then I can attempt the rest of the paper.

    Put that grade down to being under prepared. You'll be absolutely fine this time round, not to mention, all the discussions we have here allows you to learn new stuff and helps you remember stuff! I find it useful too!
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    (Original post by HarryMWilliams)
    Or as my Chemistry teacher scribbles over our papers: "RTFQ".

    I'll leave it down to you to determine what the 'F' stands for.
    Still can't figure out the rtq
    And as a note, make sure you guys read the right element when it asks for oxidation state.


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    (Original post by airheadbuster)
    Wrong. It's D.
    Explain how please
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    On Pg 55 of this thread.
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    (Original post by Tuya)
    Still can't figure out the rtq
    And as a note, make sure you guys read the right element when it asks for oxidation state.


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    "Read the .... question!" - the four letter word is quite rude?
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    can someone give me a definition of steric hindrance pleeeeeeeeeeeeeeease
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    RTFQ!!!!
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    (Original post by Hi, How are you ?)
    Can anyone explain a hydrogen bond please =)
    Anyone =)
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    guys, what would the oxidation number be for hydrogen in H20
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    (Original post by Hi, How are you ?)
    Anyone =)
    when the hydrogen bonds to either nitrogen, oxygen or flourine due to their high electronegativities!
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    (Original post by MSamuel)
    can someone give me a definition of steric hindrance pleeeeeeeeeeeeeeease
    Is when large groups prevents a species (-OH for instance) from attacking a central atom.

    That's the best I can come up with, Harry Williams and the rest of the crew can help us :cool:
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    (Original post by pineapple78)
    guys, what would the oxidation number be for hydrogen in H20
    +1
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    (Original post by James A)
    RTFQ!!!!
    what does it stand for?
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    (Original post by Hi, How are you ?)
    Anyone =)
    Occours when electronegative atoms (oxygen nitrogen and fluorine) bond to a hydrogen atom, this is a very strong intermolecular force and is much stronger then London forces. The high difference in electro negativity causes hydrogen bonds which require much higher energy to break, so molecules with hydrogen bonds have a much greater boiling point and melting point
 
 
 
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