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Chemistry: Post your doubts here!

Discussion in 'International A And AS Level' started by XPFMember, Sep 29, 2011.

  1. student2

    student2

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    genuine thnx
    May u b blessed
     
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  3. areeba240

    areeba240

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    t
    thanks alot (y)
     
  4. Rizwan Javed

    Rizwan Javed

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    Wow! :D AMAZING! That cleared so many doubts!
     
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  5. darks

    darks

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    Hey if someone could clear one or more of these syllabus points for me, it would be really helpful... :)

    -21.3. b)Explain the significance of hydrogen bonding in pairing of bases in DNA in relation to replication of genetic information.

    -e) Discuss how polymers have been designed to act as:
    i)non solvent based adhesives e.g epoxy resins and superglues
    ii)conducting polymers e.g polyacetylene

    -Also how much do we need to know about biodegradability of polymers?

    - I was unable to find drawn diagrams of primary/secondary/tertiary structures of protein in any marking scheme... If someone could provide me with the 3 diagrams with the bonding shown as we have to draw them in exam.. it would be great :D

    -electrophoresis diagram as shown in marking scheme (a 3d diagram) is really tough to draw... can we draw a 2D one.. with everything labelled?

    sorry, i know this is a lot to ask on the last day :p these were the only topics left where i am having issues. Even if you could clear one of these points, that would be great :)
     
  6. HELLNO

    HELLNO

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    Its okay lol, you explanation was clear enough (y)
     
  7. areeba240

    areeba240

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    qtn 5 (c)(i) how to find the relative peak area
    (d)(i)
    need explanation for these two parts....
     
  8. areeba240

    areeba240

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    qtn 6(f)
    plzz explain
     
  9. darks

    darks

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    Edited the quote above^^
    Discussed few points with friends so those are clear. Only these remain! Please help!! thanks!!
     
  10. HELLNO

    HELLNO

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    >Biodegradable polymers are the ones that can get hydrolysed when an acid is added to them, you don’t have to know much, just know if any bond that can be hydrolysed in the polymer then its biodegradable, also know the advantages of biodegradable polymers over non-biodegradable ones
    -Biodegradable plastics take less time to break down
    -Renewable
    -Good for the environment (no environmental harm)
    -Require less energy to produce
    -Easier to recycle
    -Non-toxic

    Thats it…

    >Hmm primary structure is basically just the basic sequence of amino acids in a polypeptide
    [​IMG]
    Secondary is the alpha helix and beta pleated sheets (I have never seen a question where they asked to draw this though)
    [​IMG]
    And tertiary is the 3D structure including the 3 bonding (Hydrogen, disulphide and ionic interactions)
    [​IMG]

    >Yes its okay, as long as everything is clear, and is fully labelled they will give you the marks :D

    Tell me if you don't get any of the above^^
     
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  11. HELLNO

    HELLNO

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    Whoops I don't know why the pictures aren't appearing!
    Can you see anything? And how do I make them appear :confused:
     
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  12. darks

    darks

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    You're a life saver :D thanks a lot!
    the images are not visible.. try lowering the size maybe? you can do that through paint.. then resize.
    The question came in s08 p4... Q8
     
    Last edited: May 14, 2017
  13. HELLNO

    HELLNO

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    Haha! Glad to know! and anytime :D
    And oh really, I will check that out :D

    Its not working :s

    Well basically the primary one is just the aminoacid with the amide link (covalent bond) joining them
    Secondary the a helix is coiled with hydrogen bonds holding the structure, Beta is the same, but less extensive hydrogen bonds
    Tertiary is the 3 bondings I mentioned above.
    Type on google images and you can see how do we draw the disulphide, hydrogen and ionic interaction...
     
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  14. darks

    darks

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    Thanks! got it! Good Luck!(y)(y)
     
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  15. sara_queen

    sara_queen

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    In w16 p41
    q5 part c)1 how do we find the relative peak area
     
  16. Saad the Paki

    Saad the Paki

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    For the reaction conditions of diazotisation, should we write the temperature as a range as in ms like " Temp <10° C " or do we write a specific temperature like " Reaction should be carried out at 5°C" ?
     
  17. Saad the Paki

    Saad the Paki

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    The relative peak area in NMR is the number of H atoms represented by that peak
     
  18. HELLNO

    HELLNO

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    <10 degrees
    Thats what the syllabus says
     
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  19. Zaki ali asghar

    Zaki ali asghar

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    In China, the concentration of blood glucose, C6H12O6, is measured in mmol / l . In Pakistan, the concentration of blood glucose is measured in mg/ dl. The unit l is a litre (1dm3 ). The unit dl is a decilitre (0.1dm3 ). A blood glucose concentration of 18.5mmol/l indicates a health problem. What is 18.5mmol/l converted to mg/ dl?
    A 33.3mg/ dl B 178mg/ dl C 333mg/ dl D 3330mg/ dl can someone solve this?
     
  20. anastasia grey113

    anastasia grey113

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    where is this from? o_O
     
  21. anastasia grey113

    anastasia grey113

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    i was doing this practical in which KMnO4 was also being used as a test for salt analysis
    y is that done?
     

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