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Edexcel As Chemistry Unit 3B

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    Hello,
    Almost 5 days remaining for this exam... I am creating a list of things you should know for this exam. Please help me complete this list.

    • Test for Halides
    • Flame tests
    • Preparation of aldehydes using simple distillation and carboxylic acids by heating under reflux
    • Preparation of halogenoalkanes
    • Test for alkenes using bromine water and acidified potassium per manganate
    • Test for halide present in a halogenoalkane by warming with sodium hydoroxide dissolved in ethanol followed by dilute nitric acid (to neutralize OH) and silver nitrate followed by ammonia solution
    • Distinguish between aldehydes and ketones using Benedicts or Fehlings solution. Formation of red precipitate confirms aldehyde
    • Drawing apparatus for simple distillation, heating under reflux and seperation of two immiscible liquids (dropping funnel)
    • Test for sulfates, sulfites and carbonates using barium chloride solution
    • Energetics: Enthalpy of neutralisation, combustion and displacement (by shumen9523)
    • Rates of reaction (by shumen9523)
    • Chemical equilibria
    • Reactions of group 2 and group 7 elements
    • Volumetric analysis: esp thiosulfate
    • Test for SO2, CO2, H2 and O2. (by sankait36): SO2 - turns acidified potassium dichromate(VI) from orange(Cr6+) to green(Cr3+), CO2 - turns lime water milky (due to insoluble calcium carbonate), H2 - test with burning splint, ignites with a pop sound, O2 - relights a glowing splint
    • Uncertainties (by sankait36): uncertainty = (maximum reading) - (minimum reading) / 2 , %uncertainty = (uncertainty / actual reading) * 100
    • In titration, discard the titre that is not concordant to 0.2 cm^3


    Please help me augment this list and also please make corrections to the above list

    Thank you
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    You should add energetics: enthalpy of neutrilisation, combustion and displacement
    rates of reactions
    there are others of course .....
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    A little thing which I don't think on the syllabus is the adding of universal indicator to a fully oxidised primary alcohol just double check it does become a Carboxylic acid... If it doesn't there's something wrong
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    i think you got just about everything
    dont forget that you still need to remember calculations such as calculating moles and mean titre
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    I think you have almost every thing, you may also want to include reducing risks in an experiment
    and also tests for gases like SO2, CO2, O2, H2 etc.

    I am also sitting for this exam, Good luck to all
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    (Original post by sankait36)
    I think you have almost every thing, you may also want to include reducing risks in an experiment
    and also tests for gases like SO2, CO2, O2, H2 etc.

    I am also sitting for this exam, Good luck to all
    Thank you
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    (Original post by quintillion)
    Thank you
    you're welcome

    Also include the test to confirm presence of -OH group in alcohol and carboxylic acid (Adding PCl5, giving steamy fumes (of HCl gas) OR Adding Sodium, we see bubbles (of H2 gas) and a white precipitate)

    also the test for ammonia gas (white fumes with a drop of conc. HCl),
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    This is really helpful! thanks for starting this thread Yeah like everyone said you got pretty much everything and I too am sitting for this exam on Wednesday
    GOOD LUCK TO EVERYONE!!! MAY WE ALL ACE IT :P
    xo
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    Any tips from anyone like revision websites with beastly revision notes etc? I'm struggling atm.
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    hey..also remember the diagrams of heating under reflux(including water inlet and water outlet)...and also the diagram of simple distillation and fractional distillation......
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    May the odds be ever in our favor.
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    hey!! do we need to write lengthy experiments in 3b 2008 spec?

    and, do we need to know displacement reactions of metals?
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    Do you need to know these? I am not sure :

    Re-crystallisation method
    How is a 250cm3 standard solution prepared?
    Using the pipette
    Using the burette


    Do we have to know these also?
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    For preparation of halogenoalkanes, why is sodium hydrogencarbonate used instead of sodium hydroxide?
    The June 2010 paper for Chemistry Unit 3, I have to say, was really quite hard.
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    (Original post by UserInvalid)
    Do you need to know these? I am not sure :

    Re-crystallisation method
    How is a 250cm3 standard solution prepared?
    Using the pipette
    Using the burette


    Do we have to know these also?
    dude, this is like one of the main areas they are likely to test you on, specially standard sol, pipette and burette are improvements for like accuracy and reliability
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    (Original post by DevilSmite)
    dude, this is like one of the main areas they are likely to test you on, specially standard sol, pipette and burette are improvements for like accuracy and reliability
    Hey ALL

    Yeaah but what about the recrystallisation method and
    especially the preparation of 250cm3 standard solution! it soo long!! :O or cud anyone brief it out?

    N any common questions in the papers?
    or predicitons? for fun :P

    btw do we have anything else to practice from? any old papers....than just the recent 6papers beginning from june 2009 to jan2012!!

    Good Luck all
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    (Original post by Lightuponlight)
    Hey ALL

    Yeaah but what about the recrystallisation method and
    especially the preparation of 250cm3 standard solution! it soo long!! :O or cud anyone brief it out?

    N any common questions in the papers?
    or predicitons? for fun :P

    btw do we have anything else to practice from? any old papers....than just the recent 6papers beginning from june 2009 to jan2012!!

    Good Luck all
    **takes deep breath* standard sol is pretty long buddy, here goes.. :P

    1) Calculate mass of solid required to make a solid of the required conc.
    2) After that place a weighing bottle a top pan balance and press the tare button so the balance is set to 0, then add the solid to the bottle until you have the required mass of the solid u calculated in 1)
    3) After measuring the mass, tip the contents of the weighing bottle i.e the mass into a beaker and wash any remaining solid from the bottle in the beaker
    4) Then ADD about 50CM3 of distilled WATER to the beaker, and stir the contents of a beaker using a glass rod , you might need to HEAT the beaker in order to dissolve the solid.
    5) After take a funnel and a 250cm3 standard flask and set it up, then pour the contents of the beaker into the funnel, make sure all the washings go through the funnel and into the FLASK
    6) Then add more distilled water to the flask until it the bottom of the meniscus is level with the mark on the standard flask.
    7) FINALLY you put a stopper on the flask and shake..SHake.. SHAKE that flask and make it POP! :P lol jkin shake the flask thoroughly so the solution is mixed well.

    hope that helped
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    Hey! Does anyone have the unit 3 jan 2012 paper and mark scheme?
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    @DevilSmite: WayBetter! Thanks alottttttt IT really did help hahah i wont 4get the POP! :P

    @jerichi: attached em GOODLUCK!
    Attached Files
  1. File Type: pdf 6CH07_01_que_20120307.pdf (437.6 KB, 399 views)
  2. File Type: pdf 6CH07_01_msc_20120209.pdf (477.9 KB, 827 views)
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    (Original post by Lightuponlight)
    @DevilSmite: WayBetter! Thanks alottttttt IT really did help hahah i wont 4get the POP! :P

    @jerichi: attached em GOODLUCK!
    :0 THANK YOU THANK YOU THANK YOU!! And good luck to you too!!!
    xo

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Updated: May 10, 2012
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