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Edexcel - Chemistry Unit 2 - 4 June 2013 watch

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    (Original post by Juliajuliajulia)
    This how I d answer it, not saying I'm right i just hope i am...
    Answer:C- because all the group 2 metals react with chlorine to form ionic salts (solids) [except for beryllium chloride which is covalent but that's solid too anyway]
    Why these are not right:
    A- Metal oxides neutralise dilute acid- so an alkaline pH like 10 would make sense (not that I knew the pH was 10)
    B- Group II sulfates follow the same solubility trends as carbonates though I'm pretty sure that's not in our spec?
    D- Group I metal carbonates except Lithium do not compose but group II do
    Hope that's right otherwise I should probably just give up x

    Thank you so much ! Best of luck
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    (Original post by Sciencefella)
    Do we need to know any drying agents? And do we need to no how to separate ethanol from water

    I have been told by a friend that anything containing Ca is a drying agent ex : calcium chloride
    for ethanol Heat it, but not to the point where the water boils!Alcohol starts to vaporize at 78 deg. C, while water does so at 100 deg. C. Heat the mixture to about 80-85 deg. C, leave it uncovered, and keep it at that temp for a while -- the alcohol will boil off, the water will stay.
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    (Original post by scientific222)
    It is C. The group 2 metals burn in chloride to form solid metal chlorides
    Thanks
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    In titration of sulphuric acid with barium hydroxide why does the conductivity of titration mixture first decreases and then increases? any ideas ?
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    (Original post by jollygood)
    In titration of sulphuric acid with barium hydroxide why does the conductivity of titration mixture first decreases and then increases? any ideas ?
    it's because at first the sulphuric acid reacts with barium hydroxide to form the insoluble barium sulphate. remember ionic solids do not conduct electricity. so the conductivity decreases as more of the sulphuric acid/barium hydroxide is converted to BaSO4. After all the acid/base reacts a reagent will be added until it's in excess, (you do not tell me what's in the burette but it is this that will be in excess) and these ions (eg Ba2+) are able to conduct electricity. so the conductivity goes up.
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    Anyone have a link to the hardest paper? I just want to see how difficult some of the questions can be, cheers!
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    June 2009 is a pretty hard paper
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    (Original post by Kurraiyo)
    it's because at first the sulphuric acid reacts with barium hydroxide to form the insoluble barium sulphate. remember ionic solids do not conduct electricity. so the conductivity decreases as more of the sulphuric acid/barium hydroxide is converted to BaSO4. After all the acid/base reacts a reagent will be added until it's in excess, (you do not tell me what's in the burette but it is this that will be in excess) and these ions (eg Ba2+) are able to conduct electricity. so the conductivity goes up.
    Thanks very much
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    (Original post by PickwickianGeek)
    Anyone have a link to the hardest paper? I just want to see how difficult some of the questions can be, cheers!
    January 2010 is the hardest of all !! try this one.
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    I find section C in june 2012 really annoying, though when checking the markscheme I facepalmed over ten times because most answers were already in the article, just didn't pay enough attention
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    Ah cheers for the replies guys. How well prepared are you lot? I don't think I'm THAT prepared, I'll probably get a low B but i think i can scrape an A from my ISA and unit 1...
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    (Original post by Kurraiyo)
    I find section C in june 2012 really annoying, though when checking the markscheme I facepalmed over ten times because most answers were already in the article, just didn't pay enough attention
    Omg this is what happened with me when I did that paper. I got the rest of stuff right but made silly mistakes in section C.
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    Jan 2013- how come double bonds are stronger than single bonds? They break easier so they should be weaker .__. or is it just the pi bond? :/
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    (Original post by Kurraiyo)
    Jan 2013- how come double bonds are stronger than single bonds? They break easier so they should be weaker .__. or is it just the pi bond? :/
    Double bonds are stronger than single bond as they have short bond length. its just pie bond thats weaker than sigma bond. Double bond requires less energy to break than energy needed to break two sigma bonds.
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    Can some1 help me with all the diagrams sort of questions? Like how many different ones are they and where can i learn them off?


    Posted from TSR Mobile
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    (Original post by jollygood)
    Double bonds are stronger than single bond as they have short bond length. its just pie bond thats weaker than sigma bond. Double bond requires less energy to break than energy needed to break two sigma bonds.
    Oh okay! Thank you very much
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    Can anyone tell me the correct definition for the sigma and pie bond


    Posted from TSR Mobile
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    (Original post by Dushyantha78)
    Can anyone tell me the correct definition for the sigma and pie bond


    Posted from TSR Mobile
    Sigma bond is formed by head on overlapping of atomic orbitals. electron density is found in plane of nuclei. Pie bond is formed by parallel overlapping of atomic orbitals and electron density is found above and below the plane of nuclei. Sigma bond is stronger than pie bond.
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    Good Luck everyone !!
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    good luck!!
 
 
 
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