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    (Original post by Georgiam247)
    Hey, anyone doing OCR A, I'm currently revising reactions of alkenes and on p130 of the OCR-heinemann textbook when talking about the addition of hydrogen halides to alkenes, it says "hydrogen halides are gases at room temperature and are bubbled into liquid alkanes"..... Did they mean liquid alkenes?!? My brain is dying
    Nope, the double bond of the alkene breaks allowing the carbon to form bonds with the hydrogen and bromine during the reaction. This now means it is an alkane (the diagram underneath).
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    Need help:

    I need to write the formula of a salt:
    Given that in the salt, Beryllium is present, and Niobium (v). further info is that dephlogisticated air is also present during the reaction
    so what is the formula of the salt? ive tried balancing out oxidation states, but I still haven't gotten the right salt formula.
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    (Original post by Georgiam247)
    You MUST do papers, my advice is save 2 full papers for the 2 weeks before the exam, and do the rest for revision. There's really no point in saving the papers since the whole point of doing them is to assess your strengths and weaknesses. Papers papers papers theyre literally the most important resource. As for note taking, you're right about it taking too long; read a chapter from the book, highlight important bits, then make posters summarising, and use flash cards to get the info into your LTM!! Don't be worried just calmly work through it good luck
    How do you mean? Like do two full past papers in those two weeks? Then use the other papers to revise?
    I agree, the book takes ages. And I'm still in the first unit. I wonder if I am even going to finish this all.
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    (Original post by A84)
    Need help:
    (Original post by A84)

    I need to write the formula of a salt:
    Given that in the salt, Beryllium is present, and Niobium (v). further info is that dephlogisticated air is also present during the reaction
    so what is the formula of the salt? ive tried balancing out oxidation states, but I still haven't gotten the right salt formula.
    Ha ha! C3L6? :-)

    Be is a 2+ Ion, Nb is a 5+ ion and O (dephlogisticated air) is a 2- ion.

    you have to make and even number from the Be and Nb so that you can balance it with the oxide ion.
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    (Original post by Cherry82)
    How do you mean? Like do two full past papers in those two weeks? Then use the other papers to revise?
    I agree, the book takes ages. And I'm still in the first unit. I wonder if I am even going to finish this all.
    You can use the papers from the old A level to revise too. Most of the syllabus is the same...just a few tweaks that you can ignore (eg Friedel-Crafts methylation of a benzene ring). The papers are arranged differently, but the questions are very similar.

    try this site...

    http://pastpapers.org/chemistry-as-papers
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    when you say sth is being oxidised or reduced, do you say the element of the compound or the compound?
    e.g. the S in SO2 is reduced / SO2 is reduced?

    thank you!
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    (Original post by samb1234)
    Board?

    Posted from TSR Mobile
    AQA
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    (Original post by blueberry389)
    when you say sth is being oxidised or reduced, do you say the element of the compound or the compound?
    e.g. the S in SO2 is reduced / SO2 is reduced?

    thank you!
    It's the element that is reduced.
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    ahh thank you! do you do aqa AS chemistry?
    (Original post by johnnypong)
    It's the element that is reduced.
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    (Original post by grapes12)
    AQA
    These are decent for edexcel so probably will be for aqa too
    http://chemrevise.org/revision-guides/
    Posted from TSR Mobile
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    No, I did my chemistry a level a while ago, I just try to help people out occasionally :-)
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    Ow haha I love Free Radical Substitution!

    I think of it as a married couples Cl2.

    The break up and feel free and horny so they want to bang. But they're naughty and only go for taken men/women :perv:

    So Cl. has an affair with CH4 :sad: and CH4 break up :sad:

    So

    Cl. + CH4 --> CH3. + HCl

    So now Cl. has a bae, but CH3 is baeless and horny

    So CH3. breaks up Cl2

    CH3. + Cl2 --> CH3Cl + Cl.

    So now CH3. has a bae, but Cl. is baeless and horny

    BUT THEN :ahee:

    All the singles bang :sexface:

    and live happily ever after
    • Thread Starter
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    Ow haha I love Free Radical Substitution!

    I think of it as a married couples Cl2.

    The break up and feel free and horny so they want to bang. But they're naughty and only go for taken men/women :perv:

    So Cl. has an affair with CH4 :sad: and CH4 break up :sad:

    So

    Cl. + CH4 --> CH3. + HCl

    So now Cl. has a bae, but CH3 is baeless and horny

    So CH3. breaks up Cl2

    CH3. + Cl2 --> CH3Cl + Cl.

    So now CH3. has a bae, but Cl. is baeless and horny

    BUT THEN :ahee:

    All the singles bang :sexface:

    and live happily ever after
    • Thread Starter
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    But anyways lol,

    QUESTION :ahee:

    Given a sample of solid calcium chloride, contaminated with calcium carbonate, describe test you would perform in order to confirm the presence of:

    (I) Calcium Ions

    (idk this lol)

    (II) Chloride ions

    Silver nitrate solution? :angelblush:
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    (Original post by Dinaa)
    But anyways lol,

    QUESTION :ahee:

    Given a sample of solid calcium chloride, contaminated with calcium carbonate, describe test you would perform in order to confirm the presence of:

    (I) Calcium Ions

    (idk this lol)

    (II) Chloride ions

    Silver nitrate solution? :angelblush:
    I) flame test calcium goes brick red

    II) Add silver nitrate, a white precipitate will form if chloride ions were present, then you could add it to ammonia, silver chloride will dissolve in conc. and dilute ammonia.
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    Does anyone have any notes on sigma/pi bonding? cheers
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    (Original post by Dinaa)
    But anyways lol,

    QUESTION :ahee:

    Given a sample of solid calcium chloride, contaminated with calcium carbonate, describe test you would perform in order to confirm the presence of:

    (I) Calcium Ions

    (idk this lol)

    (II) Chloride ions

    Silver nitrate solution? :angelblush:
    calcium...flame test? Yellow/red

    chloride ions give a white ppt of AgCl with silver nitrate. Dissolved on the addition of dil. Ammonia
    • Thread Starter
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    (Original post by BBeyond)
    I) flame test calcium goes brick red

    II) Add silver nitrate, a white precipitate will form if chloride ions were present, then you could add it to ammonia, silver chloride will dissolve in conc. and dilute ammonia.
    Omg ofc!

    thanks

    also

    An equation for the thermal decomposition of Calcium nitrate?

    And describe a test that could carry out to show the presence of nitrate ions in a solution of the sample?

    Is that the brown NO gas test? or relighting a splint test?
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    (Original post by BBeyond)
    Does anyone have any notes on sigma/pi bonding? cheers
    This video sums it up pretty well https://www.youtube.com/watch?v=ree4...DE9C8D&index=1
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    (Original post by Dinaa)
    Omg ofc!

    thanks

    also

    An equation for the thermal decomposition of Calcium nitrate?

    And describe a test that could carry out to show the presence of nitrate ions in a solution of the sample?

    Is that the brown NO gas test? or relighting a splint test?
    np

    2Ca(NO3)2 -> 2CaO + 4NO2 +O2

    could be either, would relight a glowing splint as O2 is produced, but a brown NO2 gas is also produced

    (Original post by jshep000)
    This video sums it up pretty well https://www.youtube.com/watch?v=ree4...DE9C8D&index=1
    cheers brah will check this out
 
 
 
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