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OCR Chemistry F322~ 4th June 2013~ AS Chemistry Watch

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    Hard A= 72
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    It was okay A= 76
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    Easy A= 79
    75
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    Very Easy A=82
    60
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    (Original post by needtosucceed=))
    yea the cl can go on any of the carbons
    for 4a. part 1, its told you the enthalpy change is -92 but thats when 2 moles of nh3 form, so for one mole its just half it.
    part 2, well catalysts lower activation energy so anything less than 250 is fine (except -ve numbers)
    for part 3, whenever your finding out the activation energy of a reversed reaction you just add the enthalpy change and activation energy of the forward reaction together. ignore the negative sign on the enthalpy change. so 92 + 250 = 342
    Thanks
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    Catalytic converter is a mind fock!!!
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    (Original post by Sara_A)
    Q5ei in the June 11, i dont get how the shape around the first carbon atom is tetrahedral
    Carbon forms covalent bonds. It is covalently bonded to 1 other carbon and 3 hydrogen atoms. This means there are 4 bonding pairs. From F321 you know this is tetrahedral.
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    (Original post by Sara_A)
    Q5ei in the June 11, i dont get how the shape around the first carbon atom is tetrahedral
    any carbons that arent double bonded to other carbons have a tetrahedral shape. the carbons making the bond with hydrogen so its tetrahedral
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    (Original post by Sara_A)
    Q5ei in the June 11, i dont get how the shape around the first carbon atom is tetrahedral
    Not seem the question, but if you have a C-C bond the shape will always be tetrahedral and have a bond angle of 109.5 degrees. However if you have a double C-C bond the shape will be triglanor planer with a bond angle of 120 degrees


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    (Original post by Ché.)
    As long as you get the grade, you're super good!
    Well done for the 82/90 - I am looking to get around 82-84 myself!
    Are you in Year 13!?


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    Year 12
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    (Original post by Felttip)
    Catalytic converter is a mind fock!!!
    Look at the mark scheme for Q4b) on the Jan 2011 paper. Thats all you need to know.
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    (Original post by niceguy95)
    Do the people here understand the chemistry or just know how to answer the questions
    thats an actually really good question.And one i find asking myself.
    There is some areas such as mechanisms: electrophillic addition and nucleophillic sub.. learn the dipoles,movement of electrons etc
    just learn it because it will come up somehow

    boltzmann:temp or catalyst guranteed to come up
    catalyst convertor process almost always comes up.

    carbon capture almost comes up.
    polymers;alcohol

    I think this exam is about attention to detail, there is so many areas to make mistakes like writing incomplete instead of complete combustion.
    drawing full displayed instead of sketal, significant figures. when it requests
    There are also so many areas to get marks:

    one thing that will definitely come up is definitions and enthalpy calculations.thats one i would encourgae to understand.
    how to calculate formation from combustion
    combustion from formation
    enthalpy reaction
    the reverse reaction activation etc
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    (Original post by JimmyA*)
    Yep and that is because a Carbon-Carbon double bond causes a kink in the chain shortening the length of the chain.
    I dont think the length of the chain is affected by the Carbon-Carbon double bond, You'd still have the same number of carbon atoms in the chain, the length would only be affected if it was branched...
    After Hydrogenation there are more C-H bonds so more dipoles can form so more VDW forces can form.
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    (Original post by Felttip)
    Catalytic converter is a mind fock!!!
    Not really bro

    All you need to know is

    Basically it's the conversion of harmful gases into less harmful ones (found in engines)

    So for instance carbon monoxide and nitrogen monoxide into carbon dioxide and nitrogen

    So if the question came up, just write

    CO & NO adsorb onto surface od catalyst
    Lowers the activation energy and bonds weaken
    CO2 & N2 desorb from surface

    And that's three marks

    If the ask for which metal just say palladium
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    can anyone explain catalytic converter and carbon capture for me please
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    (Original post by needtosucceed=))
    me too! let's hope its a nice paper..
    hows f325 revision going? I've definitely done more for f322 even though f325s harder :/
    its non exsistent. I did most of it last half term because i knew i would be swamped with other revision around now.

    i have 2 exams next week on tuesday. i wanna get them out of the way and just fully go 100% mode on f325.. i just need time on transitions; enthalpy and a few calculations.
    I want a C, last time my result was really bad lool. I know i am not going to get an A in f325 therefore i will get an A in f322 and f324 which are easier
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    (Original post by Jimmy20002012)
    Not seem the question, but if you have a C-C bond the shape will always be tetrahedral and have a bond angle of 109.5 degrees. However if you have a double C-C bond the shape will be triglanor planer with a bond angle of 120 degrees


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    Compound G is CH3CH=CHCH3
    So it does have a double boind, but according to the markscheme the shape around carbon atom number 1 is tetrahedral but the shape around carbon atom number 2 is trigonal planar
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    (Original post by scorpio22)
    its non exsistent. I did most of it last half term because i knew i would be swamped with other revision around now.

    i have 2 exams next week on tuesday. i wanna get them out of the way and just fully go 100% mode on f325.. i just need time on transitions; enthalpy and a few calculations.
    I want a C, last time my result was really bad lool. I know i am not going to get an A in f325 therefore i will get an A in f322 and f324 which are easier
    did u do f325 in january? we did it as a mock in class and it was killer! same ive got 2 on tuesday :/ are u aiming for an A overall?
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    (Original post by Sara_A)
    Compound G is CH3CH=CHCH3
    So it does have a double boind, but according to the markscheme the shape around carbon atom number 1 is tetrahedral but the shape around carbon atom number 2 is trigonal planar
    its not just if the compound has a double bond or not, its referring to the specific carbon. So the carbon which is tetrahedral is the single bonded one and the one thats double bonded is the trigonal planar one.
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    (Original post by Felttip)
    can anyone explain catalytic converter and carbon capture for me please
    Carbon capture storage consists of 2 stages

    Co2 is injected deep into the ocean

    It react with metal oxides to form stable carbonates

    Regarding This topic, it is what scientists do to reduce global warming

    Other methods include providing scientifical evidence global warming is occurring to the government

    Also following the Kyoto protocol
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    (Original post by Hello...)
    I dont think the length of the chain is affected by the Carbon-Carbon double bond, You'd still have the same number of carbon atoms in the chain, the length would only be affected if it was branched...
    After Hydrogenation there are more C-H bonds so more dipoles can form so more VDW forces can form.
    It is it forms a kink (like a zig zag shape), you do it in F324, so there will be less points of contact, hence why unsaturated triglycerides are liquid at room temperature(oils) and saturated triglycerides are solid at room temperature (animal fats, butter etc.).
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    (Original post by needtosucceed=))
    its not just if the compound has a double bond or not, its referring to the specific carbon. So the carbon which is tetrahedral is the single bonded one and the one thats double bonded is the trigonal planar one.
    ohhhh i get it now thanks so much!!!
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    With Boltzmann distribution do we only need to know about catalysts and tempreture?


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    (Original post by Jimmy20002012)
    With Boltzmann distribution do we only need to know about catalysts and tempreture?


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    yep and just the general features of it. like why it starts at 0,0 and what the area under the curve shows.
 
 
 
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