Results are out! Find what you need...fast. Get quick advice or join the chat
Hey there Sign in to join this conversationNew here? Join for free

Edexcel chemistry - unit 2 19th january 2012

Announcements Posted on
  • View Poll Results: WHAT DO YOU THINK YOU'LL GET ?
    <40
    2.08%
    40-50
    8.33%
    50-60
    31.25%
    60-70
    37.50%
    70-80
    20.83%

    • 55 followers
    Offline

    ReputationRep:
    (Original post by Cetacea)
    London forces (also known as instantaneous dipole-induced dipole) exist between all molecules. For example alkanes just have London forces.

    Permanent dipole-permanent dipole forces exist between polar molecules only, for example HCl is polar so will have both London forces and permanent dipole-permanent dipole forces.

    I read somewhere that you should be careful using the term van der Waals' forces because that can actually encompass London forces and permanent dipole-permanent dipole forces.

    As for ammonia, it is a polar molecule that can form hydrogen bonds so surely it must have all three kinds of force?
    Thanks.

    I always use london forces anyway, i just put vdw in case anyone didn't know london

    i would have thought that too- because the nitrogen is electronegative, but i'm thinking, perhaps the hydrogen bond overshadows the permanenent dipole dipole.
    • Thread Starter
    • 13 followers
    Offline

    ReputationRep:
    (Original post by cisne)
    do pastpaper....again do it....again do it...well,im nervous too.......lets do our revision here..
    yehhh
    Lets do it! please ask me questions... !
    Btw what resources are you using to study ?
    • 4 followers
    Offline

    ReputationRep:
    (Original post by aqua05)
    yehhh
    Lets do it! please ask me questions... !
    Btw what resources are you using to study ?
    resources.....mine is great,actually......specially published for AS students ,for the new specification.....

    ok.....lets get started...
    why water is a liquid at rtp whereas hydrogen sulphide is a gas at rtp??
    • Thread Starter
    • 13 followers
    Offline

    ReputationRep:
    (Original post by cisne)
    resources.....mine is great,actually......specially published for AS students ,for the new specification.....

    ok.....lets get started...
    why water is a liquid at rtp whereas hydrogen sulphide is a gas at rtp??
    water has hydrogen bonding which is a very strong intermolecular force. hydrogen sulfide has van der waals forces and the bonds between them is very weak thus it is a gas.

    My question to you
    what reactants do you require for oxidation of primary & secondary alcohols? Also mention the products formed & the colour change(if any)
    • 4 followers
    Offline

    ReputationRep:
    (Original post by aqua05)
    My question to you
    what reactants do you require for oxidation of primary & secondary alcohols? Also mention the products formed & the colour change(if any)
    dilute H2SO4 and K2Cr2O7 at heat under reflux...colour change is orange t green..

    ummm....whch products r formed btw??:rolleyes:




    my question is...which of the two chlorides, NaCl or MgCl2 is more covalent???
    • 55 followers
    Offline

    ReputationRep:
    (Original post by cisne)
    dilute H2SO4 and K2Cr2O7 at heat under reflux...colour change is orange t green..

    ummm....whch products r formed btw??:rolleyes:




    my question is...which of the two chlorides, NaCl or MgCl2 is more covalent???
    Mg, because it has a higher charge density than Na, so Mg will polarise/distort the chlorine atom more readily, so electron cloud is shared more, hence more covalency.
    • 4 followers
    Offline

    ReputationRep:
    (Original post by This Honest)
    Mg, because it has a higher charge density than Na, so Mg will polarise/distort the chlorine atom more readily, so electron cloud is shared more, hence more covalency.

    yeh thts correct.....whrs my questn then?? also i culdnt fully ans my other questn from aqua......do u knw??
    • 55 followers
    Offline

    ReputationRep:
    (Original post by cisne)
    yeh thts correct.....whrs my questn then?? also i culdnt fully ans my other questn from aqua......do u knw??
    :lol: I thought you actually needed to know the anser. Okay. Question:

    Write out the ionic equation for soidum hydroxide reacting with bromine in hot water
    • 2 followers
    Offline

    ReputationRep:
    I'm using the Edexcel AS Students Book and the CGP Revision Guide to study.

    Have a go at these:

    1. Write an equation for the preparation of 1-iodopropane from propan-1-ol and PI3.
    2. State the colour of iodine in (a) water (b) hydrocarbon solvent.
    • 0 followers
    Offline

    ReputationRep:
    (Original post by This Honest)
    :lol: I thought you actually needed to know the anser. Okay. Question:

    Write out the ionic equation for soidum hydroxide reacting with bromine in hot water
    ummm i dont get the question ? is it related to syllabus !
    can someone temme whats in specification ??
    • 55 followers
    Offline

    ReputationRep:
    (Original post by Cetacea)
    I'm using the Edexcel AS Students Book and the CGP Revision Guide to study.

    Have a go at these:

    1. Write an equation for the preparation of 1-iodopropane from propan-1-ol and PI3.
    2. State the colour of iodine in (a) water (b) hydrocarbon solvent.
    1) CH3CH2CH2OH+ PI3 --> CH3CH2CH2I + H3P03
    2) iodine in water; brown iodine in hydrocarbon solvent; purple
    • 4 followers
    Offline

    ReputationRep:
    (Original post by This Honest)
    1) CH3CH2CH2OH+ PI3 --&gt; CH3CH2CH2I + H3P03
    2) iodine in water; brown iodine in hydrocarbon solvent; purple
    1 is wrong. 3H3CH2CH2OH+ PI3 --> 3CH3CH2CH2I + H3P03
    • 55 followers
    Offline

    ReputationRep:
    (Original post by NutterFrutter)
    1 is wrong. 3H3CH2CH2OH+ PI3 --&gt; 3CH3CH2CH2I + H3P03
    i didnt balance, oh well
    • 55 followers
    Offline

    ReputationRep:
    (Original post by cisne)
    dilute H2SO4 and K2Cr2O7 at heat under reflux...colour change is orange t green..

    ummm....whch products r formed btw??:rolleyes:




    my question is...which of the two chlorides, NaCl or MgCl2 is more covalent???
    mild oxidation of primary alcohol turns into propanal
    vigorous oxidation of primary alcohol turns into propanoic acid

    oxidation of secondary alcohol turns into ketone
    it can't be further oxidised due to the stability of the alkyl groups
    • Thread Starter
    • 13 followers
    Offline

    ReputationRep:
    (Original post by cisne)
    dilute H2SO4 and K2Cr2O7 at heat under reflux...colour change is orange t green..

    ummm....whch products r formed btw??:rolleyes:




    my question is...which of the two chlorides, NaCl or MgCl2 is more covalent???
    when primary alcohol is heated with dilute H2SO4 & K2Cr2O7, the products formed are carboxylic acid via an aldehyde

    When secondary alcohol is heated under reflux, ketone is formed

    MgCl2 is more covalent

    My question:
    When doing the experiment under reflux why is it important that it remains open at the top?
    • Thread Starter
    • 13 followers
    Offline

    ReputationRep:
    (Original post by This Honest)
    1) CH3CH2CH2OH+ PI3 --&gt; CH3CH2CH2I + H3P03
    2) iodine in water; brown iodine in hydrocarbon solvent; purple
    Hiii can you explain to me this iodine bit reacting with alcohol
    I dont seem to understand it.. thanks
    • Thread Starter
    • 13 followers
    Offline

    ReputationRep:
    i need helppp!!!!
    I was going through the experiment on alcohols reacting with sodium.. & it says when excess ethanol evaporates it forms sodium ethoxide which is a white solid.
    & can anyone explain to me what happens when water is added to the white solid ???
    It says ethoxide ion acts as a base & removes proton from the water, forming alkaline solution ?? Can anyone give me the equation for this reaction(equation between sodium ethoxide & water..not ionic please) ??
    • Thread Starter
    • 13 followers
    Offline

    ReputationRep:
    Is the formula for phosphorus oxychloride POCl3 ??
    • Thread Starter
    • 13 followers
    Offline

    ReputationRep:
    ANYONE WHO CAN SHARE SOME OF THEIR NOTES?!
    Would really really appreciate that
    • 69 followers
    Offline

    ReputationRep:
    retaking this module, got a B in it, need a bang on A to get an A overall for AS.

Reply

Submit reply

Register

Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?
  2. this can't be left blank
    this email is already registered. Forgotten your password?
  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. By joining you agree to our Ts and Cs, privacy policy and site rules

  2. Slide to join now Processing…

Updated: April 13, 2012
New on TSR

So how did you do?

Come into the GCSE forum to share your grades

Article updates
Reputation gems:
You get these gems as you gain rep from other members for making good contributions and giving helpful advice.