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Edexcel AS level Unit 3B: Chemistry Laboratory Skills I 10/05/2016 Watch

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    Haven't been to the lab once during the entire year. I know absolutely nothing. How are you guys studying for it? Any tips?
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    Learn the tests and the most common reactions. Some organic and group 2 7 may help. But most importantly... past papers. I got a b in the mock but i want to get an a next week. When is your exam ? Mine is on tuesday
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    (Original post by ertzgrand)
    Learn the tests and the most common reactions. Some organic and group 2 7 may help. But most importantly... past papers. I got a b in the mock but i want to get an a next week. When is your exam ? Mine is on tuesday
    My problem is with the practicals, preparing organic compounds, titrations, salts etc. I haven't done a single experiment in my life lol. Mine is on Tuesday too.
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    (Original post by Electrify)
    My problem is with the practicals, preparing organic compounds, titrations, salts etc. I haven't done a single experiment in my life lol. Mine is on Tuesday too.
    Just go trough them in the book, honestly i don't remember any of the practicals i've done this year. As long as you are good at reasoning and confident with your calculations you should be ok.
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    Someone help me with the use of Potassium/Sodium Manganate and dichromate. When should I use each and what will be the results?

    NOTICE ME SENPAII
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    Senpai has noticed you!
    Well u see Mangnate is a strong oxidizing agent and we usually use it during the conversion of any alkene to a Di-Alcohol. In case of dichromate in our AS we use them in preparation of Ketone, Aldehydes (and carbooxylic acids as well) we use a milder oxidation agent(dichromate) so that the alcohol is not completely oxidized before we have the chance to distill it off. Hope it helps

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    (Original post by daddydevil)
    Someone help me with the use of Potassium/Sodium Manganate and dichromate. When should I use each and what will be the results?

    NOTICE ME SENPAII
    there are various uses of these
    potassium dichromate is used with dilute h2so4 to oxidise a primary alcohol to an aldehyde or a carboxylic acid and changes from orange (cr2o7)2- to green (Cr)3+
    potassium manganate is used to test for SO2 or an alkene and changes from purple to colorless in both cases
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    (Original post by -akuma-)
    senpai has noticed you!
    Well u see mangnate is a strong oxidizing agent and we usually use it during the conversion of any alkene to a di-alcohol. In case of dichromate in our as we use them in preparation of ketone, aldehydes (and carbooxylic acids as well) we use a milder oxidation agent(dichromate) so that the alcohol is not completely oxidized before we have the chance to distill it off. Hope it helps

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    (Original post by raza1999)
    there are various uses of these
    potassium dichromate is used with dilute h2so4 to oxidise a primary alcohol to an aldehyde or a carboxylic acid and changes from orange (cr2o7)2- to green (cr)3+
    potassium manganate is used to test for so2 or an alkene and changes from purple to colorless in both cases
    you both. I labh u <3
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    (Original post by Electrify)
    My problem is with the practicals, preparing organic compounds, titrations, salts etc. I haven't done a single experiment in my life lol. Mine is on Tuesday too.
    lol u dont need any! just focus on the pastpapers and memo the method.. i never took any lab class seriously
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    (Original post by -Akuma-)
    Senpai has noticed you!
    Well u see Mangnate is a strong oxidizing agent and we usually use it during the conversion of any alkene to a Di-Alcohol. In case of dichromate in our AS we use them in preparation of Ketone, Aldehydes (and carbooxylic acids as well) we use a milder oxidation agent(dichromate) so that the alcohol is not completely oxidized before we have the chance to distill it off. Hope it helps

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    thanks! and we always use h2so4 when oxidising.
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    How did the paper go?
    What's a test for water vapour? -_-
    What reagent and conditions were needed for converting that halogenoalkane to an alkene?
    Did you get enthalpy change for CH3OH as somewhere around 400-ish?
    Enthalpy change from graph was -1800.
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    (Original post by azefayuu)
    How did the paper go?
    What's a test for water vapour? -_-
    What reagent and conditions were needed for converting that halogenoalkane to an alkene?
    Did you get enthalpy change for CH3OH as somewhere around 400-ish?
    Enthalpy change from graph was -1800.
    Blue cobalt chloride paper turns pink
    Alcoholic KOH and reflux
    Yes
    No, it was around 1200-1250

    My answers ^^
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    (Original post by Electrify)
    Blue cobalt chloride paper turns pink
    Alcoholic KOH and reflux
    Yes
    No, it was around 1200-1250

    My answers ^^
    Ayyyyyyy,same
    Hard paper, wasn't it ??
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    (Original post by omar5478)
    Ayyyyyyy,same
    Hard paper, wasn't it ??
    Decent & different.
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    (Original post by Electrify)
    Decent & different.
    Agreed
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    What was the answer for the very last question? The one where we were asked to calculate the percentage?
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    (Original post by daddydevil)
    What was the answer for the very last question? The one where we were asked to calculate the percentage?
    I got 41 but I am pretty sure it is wrong
 
 
 
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