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    (Original post by Kadak)
    It is split into 4 modules
    Module 1 (Basic organic chemistry concepts and hydrocarbons):
    Nomenclature, Subsitution reactions,Isomers and stereoisomers,Polymers,Atom economy and Percentage Yield,Alkenes (The reactions, properties,its double bond and uses),Alkanes and everything I mentioned for alkenes apply to its except the double bond bit,Fossil fuels,Bond fission , and petroleum.
    Substitution reactions, that's what I'm missing! Thanks
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    (Original post by Abby_W31)
    Substitution reactions, that's what I'm missing! Thanks
    ALso dont forget
    Electrophiliac addition
    Nucleophiliac addition
    Hydrogenation
    Addtion reactions in general
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    (Original post by Kadak)
    ALso dont forget
    Electrophiliac addition
    Nucleophiliac addition
    Hydrogenation
    Addtion reactions in general
    THey were the ones I was after, thank you!
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    I don't get the whole bit with the colour of solution. What does that show. From the book it says something about 'the two colourless starting materials react to produce the red-brown colour of bromine'

    And on the chemrevise sheet is says the free halogen is represented by the colour of solution. Which says yellow for bromine.

    Really confused. Thanks
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    (Original post by KingThomas)
    HELP ME SOMEONE AS

    HElp me with the equation

    and state and explain any difference between the two spectra

    Thanks
    NaCO3(s) + [Acid](aq) -> Na[Acid - H](aq) + CO2(g) + H20(l)
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    (Original post by Super199)
    Right a query with my aqa textbook. Surely the oxidising ability if halogens decrease as you go down a group.

    Also I don't get the whole bit with the colour of solution. What does that show. From the book it says something about 'the two colourless starting materials react to produce the red-brown colour of bromine'

    And on the chemrevise sheet is says the free halogen is represented by the colour of solution. Which says yellow for bromine.

    Really confused. Thanks
    The colour of the solution at the end indicates the halogen present after a displacement reaction, for example, bromine in water is orange in colour, whereas chlorine in water is pale-green and iodine is brown.

    So, the use of this ionic equation might be helpful:
    Cl2 + 2Br- -> Br2 + 2Cl-, so the chlorine halogen displaces the bromide, forming chloride and bromine. The colour changes will indicate what is present essentially. The solution can either be added to Water or Cyclohexane - cyclohexane gives a more clear result as the colour changes of Br2 and I2 are very similar in water (Orange and Brown), whereas in Cyclohexane Br2 goes Orange and I2 goes Violet.

    Hope that helped.
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    (Original post by S.Ahmad)
    The colour of the solution at the end indicates the halogen present after a displacement reaction, for example, bromine in water is orange in colour, whereas chlorine in water is pale-green and iodine is brown.So, the use of this ionic equation might be helpful:Cl2 + 2Br- -> Br2 + 2Cl-, so the chlorine halogen displaces the bromide, forming chloride and bromine. The colour changes will indicate what is present essentially. The solution can either be added to Water or Cyclohexane - cyclohexane gives a more clear result as the colour changes of Br2 and I2 are very similar in water (Orange and Brown), whereas in Cyclohexane Br2 goes Orange and I2 goes Violet.Hope that helped.
    the bit about the colours I don't get. When chlorine displaces bromine surely the free halogen is bromine. Which the sheet says you get a yellow solution. But you're saying something about orange/brown.
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    (Original post by Super199)
    the bit about the colours I don't get. When chlorine displaces bromine surely the free halogen is bromine. Which the sheet says you get a yellow solution. But you're saying something about orange/brown.
    That's where the sheet is wrong, the free halogen is bromine and so the colour in water and cyclohexane would be Orange. Let me try and get a picture from my textbook.

    To summarise, its always the free halogen after the displacement reaction has occurred which determines the colour of the solution.

    Cl2 = Pale-green in both water and cyclohexane.
    Br2 = Orange in both water and cyclohexane.
    I2 = Brown in water and Violet in cyclohexane.
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    (Original post by Disney0702)
    Hi there!

    I'm an A2 AQA Chemistry student and I personally found the best way for me to revise during AS was to tackle all the past paper questions.

    This not only helped strengthen my understanding on topics I found difficult but it also helped me understand the language of the exam. I have found sometimes that the way AQA phrase their questions just puts me on the spot and makes me question as to whether I was taught that topic.

    Well as usual, yes I was taught that topic, it's just some of their questions prompts you to think outside the box from time to time and I had to learn how to do that when given an unexpected question.

    I also used my CGP AQA AS Chemistry Student book to help me and it was amazing, I totally recommend all students to get it.

    CGP Student book

    Sample Pages
    does anyone happen to have WJEC revision notes they'd be so kind as to share as i have no idea where to start and my teacher isnt the best! PLEASE HELP
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    Can someone help me with question 4g. Thanks

    http://filestore.aqa.org.uk/subjects...1-QP-JAN13.PDF
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    (Original post by Super199)
    Can someone help me with question 4g. Thanks

    http://filestore.aqa.org.uk/subjects...1-QP-JAN13.PDF


    Posted from TSR Mobile

    Don't be put off by the structure.
    First the question hints it's an isomer of an alkane.
    Remember the general formula for alkanes is CNH2N+2,there are five carbons so you plug five in and you get the molecular formula C5H12. Remember, the number of carbons determine how you name it,so five carbons means it's pentane.
    The structure is pentane.
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    (Original post by Kadak)
    Posted from TSR Mobile

    Don't be put off by the structure.
    First the question hints it's an isomer of an alkane.
    Remember the general formula for alkanes is CNH2N+2,there are five carbons so you plug five in and you get the molecular formula C5H12. Remember, the number of carbons determine how you name it,so five carbons means it's pentane.
    The structure is pentane.
    Yeah sorry I got that bit. Is the next one something to do with the surface area and the number of van der waals being less? Care to explain that question.
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    (Original post by Super199)
    Yeah sorry I got that bit. Is the next one something to do with the surface area and the number of van der waals being less? Care to explain that question.


    Posted from TSR Mobile
    Yes,since the isomer is branched,it has less surface contact area(or you can call it points of contact) than the straight chained isomer,so less Van der Waal forces are formed.

    Since the branched isomer has less Van der Waal forces,it take less energy to overcome the Van der Waal forces so it's boiling point is lower.
    Hope that helps 😃.
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    Want to get involved in this tread. Taking OCR as chemistry

    Posted from TSR Mobile
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    (Original post by Super199)
    Yeah sorry I got that bit. Is the next one something to do with the surface area and the number of van der waals being less? Care to explain that question.
    Branched alkanes have fewer points of contact between molecules this leads to fewer van der Waals' forces between the molecules. Also, the molecules can't get as close to each other and so this decreases the intermolecular forces between the molecules.
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    can any one post any useful resources or notes they have for OCR saltars B chemistry.
    thank you v much...
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    (Original post by S.Ahmad)
    Branched alkanes have fewer points of contact between molecules this leads to fewer van der Waals' forces between the molecules. Also, the molecules can't get as close to each other and so this decreases the intermolecular forces between the molecules.


    Posted from TSR Mobile

    Anyone have any good revision material for Mass spectroscopy and infrared spectroscopy?
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    (Original post by Kadak)
    Posted from TSR Mobile

    Anyone have any good revision material for Mass spectroscopy and infrared spectroscopy?

    I have some stuff from last year but i'm not sure how to upload it because its hand written.
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    I hate these drawing questions http://gyazo.com/347ea8636b70bd8cd64df98ea70316c6 What do I draw??
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    (Original post by Kadak)
    Posted from TSR Mobile

    Anyone have any good revision material for Mass spectroscopy and infrared spectroscopy?
    I have handwritten notes which I'll upload shortly.

    (Original post by BBeyond)
    I hate these drawing questions http://gyazo.com/347ea8636b70bd8cd64df98ea70316c6 What do I draw??
    Okay, first of all you need to recognise the type of reaction: this is the formation of a salt as implied by the H+ reacting with a metal: Acid + Metal -> Salt + H2. Whenever it mentions collecting gas you want to draw a displacement of water apparatus (conical flask with acid, with a bung attached to the delivery tube which is connected to an upright graduated cylinder full of water which is in a water bowl, or similar apparatus but instead the delivery tube is connected to a gas syringe.

    Apparatus 1) The water displaced is the volume of Hydrogen gas produced.
    Apparatus 2) Read off the gas syringe.
 
 
 
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