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iGCSE 2012 Chemistry Discussion

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    (Original post by studentno666)
    Can someone please post the main points which would come up for sure?
    Chemistry is my weak subject
    do all the past papers starting from 2008 upto now....U'll fell that its really easy!!
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    (Original post by Big-Daddy)
    Making CO2, oxygen or hydrogen? Since when is any of that on the syllabus?

    I'm aware you need to know H2O2's reaction to form water and oxygen, but would you really say that you "make" oxygen through that reaction? And how do you "make" hydrogen?
    to make hydrogen u need to have hydrogen peroxide and then add manganese (IV) oxide which acts as a catalyst...
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    can anyone give me a detailed answer on how fractions are obtained by fractional distillation of crude oil??
    (4 mark detailed answer)
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    (Original post by nithpriya)
    can anyone give me a detailed answer on how fractions are obtained by fractional distillation of crude oil??
    (4 mark detailed answer)
    The crude oil is fed in a vaporised form into the fractionating column. The heavier fractions (eg bitumen) immediately condense and sink to the bottom and the lighter fractions like gasoline rise to the top of the column as they are less dense. They are then fractioned off according to their boiling points as they all have different boiling points which allows them to be separated in the column. The fractions are then used for different purposes but some may be cracked to form more useful fractions.

    Hope that helped somewhat.


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    (Original post by Graceyfave)
    The crude oil is fed in a vaporised form into the fractionating column. The heavier fractions (eg bitumen) immediately condense and sink to the bottom and the lighter fractions like gasoline rise to the top of the column as they are less dense. They are then fractioned off according to their boiling points as they all have different boiling points which allows them to be separated in the column. The fractions are then used for different purposes but some may be cracked to form more useful fractions.

    Hope that helped somewhat.


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    thanx helped a lot
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    hey everyone hows chemistry studies coming along?
    I'm fed up of studies cant believe there are more to come(a/l, college). Gotto go back to studying. :ciao:

    My major question

    -When will all studies end?-:confused:
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    (Original post by Big-Daddy)
    Making CO2, oxygen or hydrogen? Since when is any of that on the syllabus?

    I'm aware you need to know H2O2's reaction to form water and oxygen, but would you really say that you "make" oxygen through that reaction? And how do you "make" hydrogen?
    BigDaddy we need to know the experiment for evolution of carbon dioxide and oxygen and come one you must know ONE experiment for evolution of hydrogen?
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    (Original post by sahajkaur)
    BigDaddy we need to know the experiment for evolution of carbon dioxide and oxygen and come one you must know ONE experiment for evolution of hydrogen?
    Could you post the experiments?


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    http://www.4shared.com/file/5GMs6Cx5...de_to_Ch.html?

    Best chem notes!! (different from before)
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    (Original post by Graceyfave)
    Could you post the experiments?


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    For Carbon dioxide just add HCl to any carbonate (most commonly calcium) and it can be collected over water or downward delivery.
    For Oxygen Manganese dioxide is the catalyst and Hydrogen peroxide decomposes slowly to form oxygen and water.

    For hydrogen just react a metal with an acid
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    (Original post by sahajkaur)
    For Carbon dioxide just add HCl to any carbonate (most commonly calcium) and it can be collected over water or downward delivery.
    For Oxygen Manganese dioxide is the catalyst and Hydrogen peroxide decomposes slowly to form oxygen and water.

    For hydrogen just react a metal with an acid
    You are a god hahah. I don't have to search madly through my notes now!


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    (Original post by Graceyfave)
    You are a god hahah. I don't have to search madly through my notes now!


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    for physics do you know the advantages and disadvantages of using different energy sources? ( i dont have it in my notes
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    Hello! Was just looking through the spec and there was a point that I'm not really sure about. It's in bold though, so will only show up on the 1hour paper! It's "evaluate the factors relevant to the choice of method used in the manufacture of ethanol, for example the relative availability of sugar cane and crude oil." Please, anyone know what information we need to know regarding this?


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    (Original post by sahajkaur)
    for physics do you know the advantages and disadvantages of using different energy sources? ( i dont have it in my notes
    Go to the link below

    http://wiki.answers.com/Q/What_are_t...energy_sources

    Hope it helps!!
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    (Original post by _ashT)
    Hello! Was just looking through the spec and there was a point that I'm not really sure about. It's in bold though, so will only show up on the 1hour paper! It's "evaluate the factors relevant to the choice of method used in the manufacture of ethanol, for example the relative availability of sugar cane and crude oil." Please, anyone know what information we need to know regarding this?


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    I think it means what are the advantages and disadvantages of different methods to make ethanol.

    And what method to use at different countries. eg a country with good climate for growing sugar crops could use fermentation, and a country with plenty of crude oil could use hydration of ethene.
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    (Original post by nithpriya)
    I think it means what are the advantages and disadvantages of different methods to make ethanol.

    And what method to use at different countries. eg a country with good climate for growing sugar crops could use fermentation, and a country with plenty of crude oil could use hydration of ethene.
    ah okay, thank you so much! Also, there's another point that I'm not too sure of: "explain how the methods of extraction of the metals in this section are related to their positions in the reactivity series."?


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    (Original post by nithpriya)
    http://www.4shared.com/file/5GMs6Cx5...de_to_Ch.html?

    Best chem notes!! (different from before)
    these are amazing!
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    (Original post by l-g)
    these are amazing!
    thnx but found them too late!
    wish i had them earlier
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    Hi all, does anyone have the name of the guy who does chemistry videos that someone has been posting? I can't find the link like Alex something? Thanks!


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    (Original post by Graceyfave)
    Hi all, does anyone have the name of the guy who does chemistry videos that someone has been posting? I can't find the link like Alex something? Thanks!


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    I have a physics person not chem :/

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Updated: October 24, 2012
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