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

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    Hard A= 72
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    Easy A= 79
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    Can someone explain 6 c i on June 2010? Thanks
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    Can anybody help me with the calculation in Question 3 (d) of this paper, it seems different to a normal % yield question.

    Any help appreciated.

    http://www.ocr.org.uk/Images/131287-...-resources.pdf
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    guys for the questions that say write the equation for the oxidation reaction. is it just [o] for aldehydes and ketones and 2[o] for carboxys. then the product is always just one mole of what was being formed
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    (Original post by needtosucceed=))
    its in the first post of this thread
    Thank you
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    Hello, i'm retaking this unit,
    and didn't do any F322 for 1 full year.
    Still didn't do any paper or anything, I'm thinking of starting my revision now.
    People say in this case do "cramming", what is cramming so I can do it?

    EDIT: Searched in google, understood it but the question is now does it work?
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    (Original post by flygerianmc)
    guys for the questions that say write the equation for the oxidation reaction. is it just [o] for aldehydes and ketones and 2[o] for carboxys. then the product is always just one mole of what was being formed
    Yeah!
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    (Original post by flygerianmc)
    guys for the questions that say write the equation for the oxidation reaction. is it just [o] for aldehydes and ketones and 2[o] for carboxys. then the product is always just one mole of what was being formed
    yep one mole of your product.yep thats correct. and waters formed
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    What are the conditions for hydrogenation??

    Posted from TSR Mobile
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    (Original post by the A* guy)
    Can anybody help me with the calculation in Question 3 (d) of this paper, it seems different to a normal % yield question.

    Any help appreciated.

    http://www.ocr.org.uk/Images/131287-...-resources.pdf
    do the normal actual/theoretical

    then if u look at the equation its not a 1:1 ratio of methane:hydrogen

    so scale it up by either multiplying the methane moles by 3 or dividing the hydrogen moles by 3
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    (Original post by needtosucceed=))
    yep one mole of your product.yep thats correct. and waters formed
    ty
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    (Original post by wndms)
    What are the conditions for hydrogenation??

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    Nickel catalyst, 523 K and high pressure.
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    (Original post by wndms)
    What are the conditions for hydrogenation??

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    nickel catalyst. 300oc
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    This sounds really silly...

    BUT
    I always forget which way equilibriums shift :'( and i just can't seem to remember...
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    Hello, i'm retaking this unit,
    and didn't do any F322 for 1 full year.
    Still didn't do any paper or anything, I'm thinking of starting my revision now.
    People say in this case do "cramming", but the question is now does "cramming" work?
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    (Original post by danlocke)
    Can someone explain 6 c i on June 2010? Thanks
    deltaH = q x n, rearrange this equation is q = deltaH x n

    divide the enthalpy change given in the equation by 4 because you want 1 mole of it, but that enthalpy change is for 4 moles

    then multiply this answer by 2.5x10^5
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    (Original post by Blashnet)
    Hey!

    I got 49/60 unit one (72 ums) and 37/40 in pracs (dont know what UMS)

    Anyone got any idea of what raw/ums mark i'd need for an A?
    112
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    (Original post by Blashnet)
    This sounds really silly...

    BUT
    I always forget which way equilibriums shift :'( and i just can't seem to remember...
    increase temp = shift in the endothermic direction
    decrease temp = shift in the exothermic direction

    increase pressure = shifts to side with fewer moles of gas
    decrease pressure = shifts to side with more moles of gas

    the opposite occurs for each change,
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    (Original post by needtosucceed=))
    lol fair enough. you should be fine if you scrape an A, ur practicals are high
    Niceeeeeee
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    (Original post by Blashnet)
    This sounds really silly...

    BUT
    I always forget which way equilibriums shift :'( and i just can't seem to remember...
    I swear I gave a good method time but here it is again

    I just remember t as if it exothermic in foward direction (- delta H)

    Increase temp shifts to left (EXIL)
    Decrease temp shifts right. (EXDR)

    If its endothermic in foward direction (+ delta H)
    Increase temp shifts to the right (ENIR)
    Decrease temp shifts to the left (ENDL)

    Stupid method put that's how I remember for temperture

    As for pressure

    Ch4 + br2-----> 4ch3br
    Increase pressure shifts to side with fewer moles ( so in this reaction left as it has 2 moles)

    Decrease pressure shifts to side with more moles (so in this case the right as there 4 moles)

    *only use pressure if has a gas (g) symbol on all products and reactants


    My weird methods of remembering things
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    First post of 100 page I would like to thank everybody for reading this.
    Anyways back to topic, does cramming work or not?
 
 
 
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