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***2013 LC Chemistry Before/After***

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    #602
    Glee_GG
    Registered Users Posts: 522 ✭✭✭Glee_GG


    Are the winkler reagents Manganese sulfate and potassium iodide or manganese sulfate and sulfuric acid?


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    #603
    MarieCurie22
    Registered Users Posts: 204 ✭✭MarieCurie22


    Glee_GG wrote: »
    Are the winkler reagents Manganese sulfate and potassium iodide or manganese sulfate and sulfuric acid?

    Manganese sulfate and alkaline potassium iodide :)


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    #604
    Glee_GG
    Registered Users Posts: 522 ✭✭✭Glee_GG


    MarieCurie22 wrote: »
    Manganese sulfate and alkaline potassium iodide :)

    Cheers, wrote them both down in my book and had them both crossed out!


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    #605
    MarieCurie22
    Registered Users Posts: 204 ✭✭MarieCurie22


    oooh lads i like the look of 2009 q3 if i were an examiner id be asking that again


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    #606
    [Deleted User]
    Posts: 0 ✭ [Deleted User]


    MarieCurie22 wrote: »
    Also you guys would be idiots (not saying you are yet :P) if you go into the exam not knowing:
    Mn+7 = purple
    Mn+4 = brown
    Mn+2 = colourless

    You add H2SO4 to provide protons to enure complete redution of Mn+7 to Mn+2 NOT Mn+4
    Mn+4 is in the BOD expriment its the brown percipitate...
    Mn+2 is a catalyst (autocatalysis!)

    We add conc H2SO4 to get rid of the Brown ppt in the experiment and liberate iodine right?


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    #607
    Glee_GG
    Registered Users Posts: 522 ✭✭✭Glee_GG


    Should be my best exam so not that worried about this, have a feeling experiments are going to be pretty hard seeing as last years were just beautiful in all fairness! Have a feeling anion testing is going to make a sneaky appearance, once the soap experiment stays away should be ok.


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    #608
    [Deleted User]
    Posts: 0 ✭ [Deleted User]


    MarieCurie22 wrote: »
    oooh lads i like the look of 2009 q3 if i were an examiner id be asking that again

    Anion tests scare me that needs to stay away!


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    #609
    MarieCurie22
    Registered Users Posts: 204 ✭✭MarieCurie22


    Deleted User wrote: »
    Anion tests scare me that needs to stay away!

    Ok heres 2 out of the way:

    Test for a chloride ion:
    Princess chloride is trapped in an aqueous solution...
    Along come sliver knight (silver nitrate) to rescue her
    They then try escape on his white horse percipitate...
    But the evil queen dilute ammoniam returns! and they dissappear and drown :(


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    #610
    Parawhore.xD
    Registered Users Posts: 571 ✭✭✭Parawhore.xD


    MarieCurie22 wrote: »

    Ionisation Energy:
    The energy required to remove the most loosely bound electron from a neutral atom in its gaseous state.

    Ionisation energies....
    -Increase across the period:
    -Due to the decrease in atomic radius (See above)
    -Increase in atomic charge (more protons)
    -Decrease down the period:
    -Due to increasing atomic radius.
    -Screening effect of inner electrons!

    You haven't accounted for the interruption of the increase across groups 1&2 and 5&6 because of the half filled sublevels increased stability.


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    #611
    MarieCurie22
    Registered Users Posts: 204 ✭✭MarieCurie22


    Sulfate and Sulfite:
    Sulfate and sulfite are twin brothers walking in the woods...
    They come across a bear (Barium chloride) and "poop" themselves (white percipitate)
    Then sulfite remembers the Hyrogen Courage Liquid (HCl) in back pocket...
    He shares it with his brother...
    However Sulfite disappears and runs like the wind (ppt goes)
    His brother doesnt seem to gain any courage and stands there frozen forever (ppt stays!)


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    #612
    [Deleted User]
    Posts: 0 ✭ [Deleted User]


    MarieCurie22 wrote: »
    Sulfate and Sulfite:
    Sulfate and sulfite are twin brothers walking in the woods...
    They come across a bear (Barium chloride) and "poop" themselves (white percipitate)
    Then sulfite remembers the Hyrogen Courage Liquid (HCl) in back pocket...
    He shares it with his brother...
    However Sulfite disappears and runs like the wind (ppt goes)
    His brother doesnt seem to gain any courage and stands there frozen forever (ppt stays!)

    If only there was a story for them all!


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    #613
    Hamza Malik
    Registered Users Posts: 161 ✭✭Hamza Malik


    So as a last minute study attempt, what question 3 experiment should I revise?


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    #614
    MarieCurie22
    Registered Users Posts: 204 ✭✭MarieCurie22


    Phosphate:
    Goes canary yellow! Ammonium Molybdate sounds to me like an exoctic bird so it must have something to do with canaries!
    Cannaries fly but the acid we want is in the ground in fertilizer (occasionally) so it must be nitric acid!


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    #615
    Parawhore.xD
    Registered Users Posts: 571 ✭✭✭Parawhore.xD


    MarieCurie22 wrote: »
    Sulfate and Sulfite:
    Sulfate and sulfite are twin brothers walking in the woods...
    They come across a bear (Barium chloride) and "poop" themselves (white percipitate)
    Then sulfite remembers the Hyrogen Courage Liquid (HCl) in back pocket...
    He shares it with his brother...
    However Sulfite disappears and runs like the wind (ppt goes)
    His brother doesnt seem to gain any courage and stands there frozen forever (ppt stays!)

    I'm sorry...what?!


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    #616
    MarieCurie22
    Registered Users Posts: 204 ✭✭MarieCurie22


    Hamza Malik wrote: »
    So as a last minute study attempt, what question 3 experiment should I revise?

    A quick look over:
    Anions (see above) and flame tests
    Rates of rxn (aLL)
    equilirbrium and
    those dodgy water ones! like chlorine in h20 (NB hypochlorous acid!!!!)


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    #617
    Hamza Malik
    Registered Users Posts: 161 ✭✭Hamza Malik


    What are the conditions necessary for a dust explosion? :eek:


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    #618
    Prodigious
    Closed Accounts Posts: 2,827 ✭✭✭Prodigious


    Dust!


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    #619
    MarieCurie22
    Registered Users Posts: 204 ✭✭MarieCurie22


    Hamza Malik wrote: »
    What are the conditions necessary for a dust explosion? :eek:

    Easy peasy calm!!!
    -Enclosed space
    -Flamable dust
    -A spark/ignition....


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    #620
    [Deleted User]
    Posts: 0 ✭ [Deleted User]


    Hamza Malik wrote: »
    What are the conditions necessary for a dust explosion? :eek:

    High volumes of small particles?


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    #621
    Parawhore.xD
    Registered Users Posts: 571 ✭✭✭Parawhore.xD


    [Deleted User] wrote: »
    High volumes of small particles?

    It's high concentration either I think?


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    #622
    MarieCurie22
    Registered Users Posts: 204 ✭✭MarieCurie22


    Parawhore.xD wrote: »
    It's high concentration either I think?

    Guys its CONDIOTIONS
    the dust must be flammable yes when we say dust we mean finely ground particles in high concentration but you need it to be flammable or else it wont explode...
    you also need an enclosed space for this to occur at all
    and an ignition to start it all off!


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    #623
    SecondMan
    Registered Users Posts: 236 ✭✭SecondMan


    MarieCurie22 wrote: »
    Guys its CONDIOTIONS
    the dust must be flammable yes when we say dust we mean finely ground particles in high concentration but you need it to be flammable or else it wont explode...
    you also need an enclosed space for this to occur at all
    and an ignition to start it all off!

    You don't be playing with dust silos Mrs Curie! A science experiment already got the better of you before..*cough*radiation*cough*


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    #624
    Parawhore.xD
    Registered Users Posts: 571 ✭✭✭Parawhore.xD


    MarieCurie22 wrote: »
    Guys its CONDIOTIONS
    the dust must be flammable yes when we say dust we mean finely ground particles in high concentration but you need it to be flammable or else it wont explode...
    you also need an enclosed space for this to occur at all
    and an ignition to start it all off!

    I'm well aware it's conditions plural, no need to take on such a condescending tone thanks.


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    #625
    Hamza Malik
    Registered Users Posts: 161 ✭✭Hamza Malik


    Eek does the intermediate formation theory explain homogeneous, heterogeneous or autocatalysis ?


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    #626
    MarieCurie22
    Registered Users Posts: 204 ✭✭MarieCurie22


    Parawhore.xD wrote: »
    I'm well aware it's conditions plural, no need to take on such a condescending tone thanks.

    I was trying to help you...


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    #627
    MarieCurie22
    Registered Users Posts: 204 ✭✭MarieCurie22


    Hamza Malik wrote: »
    Eek does the intermediate formation theory explain homogeneous, heterogeneous or autocatalysis ?

    Homogenoous.....they have to be in the same phase for intermediate compounds to form...

    Heterogenous is....surface adsorbtion...


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    #628
    Parawhore.xD
    Registered Users Posts: 571 ✭✭✭Parawhore.xD


    MarieCurie22 wrote: »
    I was trying to help you...

    If I want help I'll ask for it.


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    #629
    Hamza Malik
    Registered Users Posts: 161 ✭✭Hamza Malik


    MarieCurie22 wrote: »
    Homogenoous.....they have to be in the same phase for intermediate compounds to form...

    Heterogenous is....surface adsorbtion...

    ill surely get an A1 now :3


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    #630
    Scuid Mhór
    Registered Users Posts: 2,326 ✭✭✭Scuid Mhór


    Parawhore.xD wrote: »
    If I want help I'll ask for it.

    Ohhhhhhhhhhhh


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    #631
    SecondMan
    Registered Users Posts: 236 ✭✭SecondMan


    Parawhore.xD wrote: »
    If I want help I'll ask for it.

    Tension in the forum,
    Let the tension free,
    We all jump up in a one, two, three.


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