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    (Original post by Super199)
    Can someone help me with 1a and b?

    Is 1a barium? Can someone explain it to me.


    Thanks
    It's barium sulphate

    It's a white precipitate

    Ba2+ (aq) + SO42- (aq) -------> BaSO4 (s)


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    (Original post by ThatMadClown)
    It's barium sulphate

    It's a white precipitate

    Ba2+ (aq) + SO42- (aq) -------> BaSO4 (s)


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    Isn't it just barium? But I don't get why it is. Isn't barium quite vigorous when it comes to water so surely it won't just fizz.

    What's part b?
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    I'm doing AQA.
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    Hi I'm on AQA AS and finished unit 1 and 2, feel free to ask any questions (PM me)
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    Could anyone taking AQA chemistry AS help shed some light onto the practicals we will likely be doing?

    I'm self-teaching and all the written stuff is fine, but I've only practised titrations so slightly concerned about the practical element!
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    (Original post by haemo)
    You're right, X is just barium.

    The reaction with water is: Ba + 2H2O -> Ba(OH)2 + H2

    The other reaction is: BaCl2 + Na2SO4 -> BaSO4 + 2NaCl
    (this is what I believe the above poster meant)
    What about part b?
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    Yo guys I desperately need help with a gas calculation:

    Show by calculation that the expected volume of CO2 is greater than the 64cm3 obtained.
    Assume that 1 mol of CO2 occupies 24.0dm3

    This is only part of a bigger Q about the reaction of H2SO4 and MgCO3, the number of moles of H2SO4 is 0.005 and the number of moles of MgCO3 is 0.00356.

    I assumed from the info given I needed to use the moles = Volume/24dm3 equation, and I thought that I would substitute in 0.00356 for the number of moles because there's a 1:1 ratio and MgCO3 is the limiting reagent.... but the answer is wrong? I got 96cm3 and the answer is 71.4cm3, suggesting that the correct number of moles of CO2 is 0.002975.

    I'm guessing I'm missing a really obvious way to get the number of moles of CO2? Its driving me insane!!!!!!

    Thank you
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    Anyone who does OCR Salters B done the coursework yet?

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    (Original post by Golden hawk)
    The answer on that isa is wrong, it should be 0.00356 times 24000 and this should give 85.44cm3
    You're joking?!? Oh my gosh I spent so long wondering what was wrong with me! Thank you
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    (Original post by Georgiam247)
    You're joking?!? Oh my gosh I spent so long wondering what was wrong with me! Thank you
    Don't worry I spent ages trying to figure out what I was doing wrong also, so I showed the teacher and she said that the markscheme was wrong all along.
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    (Original post by Golden hawk)
    Don't worry I spent ages trying to figure out what I was doing wrong also, so I showed the teacher and she said that the markscheme was wrong all along.

    That's so annoying! Was that the only wrong answer? I might as well not bother marking the rest if there's more
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    Hey guys,

    I was just wondering for those on the Edexcel board for chemistry whether you have done the double-salt preparation for an assessed practical?

    Thanks guys
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    AQA chemistry

    Any easy way to remember Halogen equations for unit 2??
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    (Original post by Georgiam247)
    That's so annoying! Was that the only wrong answer? I might as well not bother marking the rest if there's more
    Thats the only wrong answer.
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    Hey guys, does anyone have the Edexcel GCE AS Chemistry specification that's explained in detail for each point? Unit 1 and unit 2 please
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    (Original post by Anne james)
    Hey guys, does anyone have the Edexcel GCE AS Chemistry specification that's explained in detail for each point? Unit 1 and unit 2 please
    Hey, I'm not doing edexcel but i'd imagine you can get the spec on the website right?
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    Hi everyone,

    I have to do some questions about a double-salt preparation that we did and was wondering if someone could help me with a few of the questions. Rep will be given to anyone that helps.

    Method:

    Make one of the salts
    Make the other salt
    Mix them together
    Boil some of the liquid off
    Leave to crystallize

    Firstly, why is the volume of the solution reduced? i.e. why is some of the liquid boiled off?

    Also, when we were making one of the salts (ammonium sulfate solution) why did I have to keep on adding ammonia until red litmus turned red?

    Finally, when calculating moles, do you include the water of crystallization in your calculations?

    Thanks guys!
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    (Original post by johnjames9)
    Hi everyone,

    I have to do some questions about a double-salt preparation that we did and was wondering if someone could help me with a few of the questions. Rep will be given to anyone that helps.

    Method:

    Make one of the salts
    Make the other salt
    Mix them together
    Boil some of the liquid off
    Leave to crystallize

    Firstly, why is the volume of the solution reduced? i.e. why is some of the liquid boiled off?

    Also, when we were making one of the salts (ammonium sulfate solution) why did I have to keep on adding ammonia until red litmus turned red?

    Finally, when calculating moles, do you include the water of crystallization in your calculations?

    Thanks guys!
    1) to make it as saturated as possible: crystallisation occurs when a solution is saturated so when sufficient water has evaporated, by heating you get some of that done!

    2) you mean red-> blue? To ensure ammonia is in excess and so all surface (practically) had reacted.

    3) very much depends on context. To calc moles of a crystalline solid you weigh? Yes include in Mr value.
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    Hi, just came across this forum - I have a qualitative tomorrow on investigating reactions with lead ... any advice or has any one has already done it?
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    Hey guys,

    I was wondering, does anyone have a tutor for chemistry? I don't have any particular areas that I suck at but my teacher is so careless I feel like it'd be a good idea to get one. Anybody seen a lot of benefit from a tutor?
 
 
 
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