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    some hard stuff, but definitely an interesting module minus rates
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    (Original post by MedMed12)
    some hard stuff, but definitely an interesting module minus rates
    Hi MedMed 12 how are you?

    want to revise F325?
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    (Original post by otrivine)
    Hi MedMed 12 how are you?

    want to revise F325?

    Hey otrivine,

    well thanks yourself?

    Sure! Erm I dont know f215 as well as you but we can give it ago!


    define operon (2 marks)

    explain the advantage of synthesising beta galactosidase when lactose is present only (2 marks)





    why did I take biology ? haha!
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    (Original post by MedMed12)
    Hey otrivine,

    well thanks yourself?

    Sure! Erm I dont know f215 as well as you but we can give it ago!


    define operon (2 marks)

    explain the advantage of synthesising beta galactosidase when lactose is present only (2 marks)


    T


    why did I take biology ? haha!
    thanks , not biology I mean F325, chemistry unit 5 questions
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    Here's a couple of questions:

    What must you never include in a Kc equation and why?(2)

    What does the pKa value indicate about an acid's strength?(1)
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    H2O because its In excess

    Tells you the extent of dissociation therefore strength of acid
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    (Original post by Crabbiey)
    Here's a couple of questions:

    What must you never include in a Kc equation and why?(2)

    What does the pKa value indicate about an acid's strength?(1)

    1) In Kc equation you never include molecules/compounds that are in solid or liquid state this is because they are not in (equilibrium) constant, and because the particles are not able to spread because in solid and liquid the molecules are not able to move freely as compared to gases or in aqeous solutions,

    2) Lower Pka value indicates that the strength of the acid is stronger
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    (Original post by otrivine)
    thanks , not biology I mean F325, chemistry unit 5 questions
    I think I'm blind haha!

    Okay sorry about that hmmm what affects Kc and why? 2-3 marks

    what is entropy?


    when is a reaction feasible?



    Outline the benefits of fuel cells? the disadvantages?


    redox titrations - what colour changes happens with Mn?
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    (Original post by otrivine)
    1) In Kc equation you never include molecules/compounds that are in solid or liquid state this is because they are not in (equilibrium) constant, and because the particles are not able to spread because in solid and liquid the molecules are not able to move freely as compared to gases or in aqeous solutions,

    2) Lower Pka value indicates that the strength of the acid is stronger
    Second one correct. For the first one that wasn't the answer I was thinking of but it sounds correct! I should have been more specific - I meant when the compounds are in aqueous (I've only ever done Kc in aq so I naturally assumed people would assum that too) you must eliminate water as it is in excess so much so its concentration outweighs all the other compounds'.
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    (Original post by MedMed12)
    I think I'm blind haha!

    Okay sorry about that hmmm what affects Kc and why? 2-3 marks

    what is entropy?


    when is a reaction feasible?



    Outline the benefits of fuel cells? the disadvantages?


    redox titrations - what colour changes happens with Mn?
    No worries

    1) Kc is only affected by temperature, this is because Kc is an equilibrium constant and only gas and aqueous compounds/molecules are affected only by temperature. Kc increases if forward reaction is endothermic and Kc decreases if forward reaction is exothermic. Also, Kc is affected by temp as it affects the value of Kc , so if Kc< 1 then reactant side is predominant and Kc>1 is product favoured.

    2) Entropy is the quantative measure of the degree of disorder in a system

    3) A reaction is feasible if the value of deta G< 0 , the value of deta G is determined by the free energy equation/formula which is deta G= deta H - Tdeta S



    4) The advantages of fuel cells= less pollutant and less co2 is released and greater efficiency. Also, is publically and poltically accepted (more).

    disadvantages= uses toxic chemicals in their production, fuel cells have a limited life time and requires regular replacement and disposal following high production costs, the feasibility of storing a pressurized liquid and current adsorbers and absorbers have a limited life time.

    5) It turns from purple (Mno4-) to almost colourless/ dilute purple ( Mn2+)
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    (Original post by Crabbiey)
    Second one correct. For the first one that wasn't the answer I was thinking of but it sounds correct! I should have been more specific - I meant when the compounds are in aqueous (I've only ever done Kc in aq so I naturally assumed people would assum that too) you must eliminate water as it is in excess so much so its concentration outweighs all the other compounds'.
    I thought that has got to do more with Kstab which involves not including water in the expression
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    For entropy, I don't understand how the units of 'disorder in a system' can be J K^-1 mol^-1 :s
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    (Original post by otrivine)
    No worries

    1) Kc is only affected by temperature, this is because Kc is an equilibrium constant and only gas and aqueous compounds/molecules are affected only by temperature. Kc increases if forward reaction is endothermic and Kc decreases if forward reaction is exothermic. Also, Kc is affected by temp as it affects the value of Kc , so if Kc< 1 then reactant side is predominant and Kc>1 is product favoured.

    2) Entropy is the quantative measure of the degree of disorder in a system

    3) A reaction is feasible if the value of deta G< 0 , the value of deta G is determined by the free energy equation/formula which is deta G= deta H - Tdeta S



    4) The advantages of fuel cells= less pollutant and less co2 is released and greater efficiency. Also, is publically and poltically accepted (more).

    disadvantages= uses toxic chemicals in their production, fuel cells have a limited life time and requires regular replacement and disposal following high production costs, the feasibility of storing a pressurized liquid and current adsorbers and absorbers have a limited life time.

    5) It turns from purple (Mno4-) to almost colourless/ dilute purple ( Mn2+)


    all correct
    haha you make feel like I'm failing with your perfect answers to the bio and chem questions I ask you!
    I really do hope you get the grades you want/need, you work so hard its unreal!
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    (Original post by MedMed12)
    all correct
    haha you make feel like I'm failing with your perfect answers to the bio and chem questions I ask you!
    I really do hope you get the grades you want/need, you work so hard its unreal!

    Hhaha thank, you are doing very well too


    But I was unsure for question 1 to be honest, was my reason for why Kc is only affected by temp?
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    (Original post by otrivine)
    Hhaha thank, you are doing very well too


    But I was unsure for question 1 to be honest, was my reason for why Kc is only affected by temp?
    aha not well enough hows maths going? c4 right?

    ahhh actually, I dont think they'll ask that question, my teacher gave it to us as a stretch and challenge. basically temp affect kc/kp as more or less product is produced, whereas the other factors such as conc, volume only affect position of equilibrium.
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    (Original post by MedMed12)
    aha not well enough hows maths going? c4 right?

    ahhh actually, I dont think they'll ask that question, my teacher gave it to us as a stretch and challenge. basically temp affect kc/kp as more or less product is produced, whereas the other factors such as conc, volume only affect position of equilibrium.

    C4 is okish , a big jump from c3 but finding vectors a nightmare

    What about u ?
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    (Original post by otrivine)
    C4 is okish , a big jump from c3 but finding vectors a nightmare

    What about u ?

    im loving c4 compared to C3. Integration by substitution and vectors I need to slow down on and practice abit, but iA it'll be okay!

    Dw, just keep working hard.
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    (Original post by Wheeeto)
    I have the jan 2013 QP and MS, so if anyone wants it, just pm me your email and i'll send it to you
    Messaged You Thanks.
    • Study Helper
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    Just got given 46 questions on transition elements and after getting through about half of them without any help the rest seem very routine, I'm hoping that's how I find this exam as well.

    How's everyone's revision going?

    Edit: As if this actually got negged, how sad
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    hey, do we need to learn about partial pressure for f325?
 
 
 
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