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    Different exam board but anyone know why question 2 is b


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    (Original post by Supermanxxxxxx)
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    Different exam board but anyone know why question 2 is b


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    Think about O2 - it has to be two molecules of oxygen so you have different combos, like 16O with 18O etc. Write them out and see how many you get, and then it's 5!
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    (Original post by 97Y)
    Kind sir, please leave our thread. I'm sure that you have some thermodynamics to revise, whilst we have an exam in 12 hours.
    I am also resitting the paper lol.
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    (Original post by Matthewg97)
    Could some please tell me the AQA definition of relative molecular mass? Thanks
    average mass of one molecule/ 1/12 mass of one atom of 12^C just do the formula its easier to remember
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    It's just so horrible to come onto a thread and basically say all of us resitters are stupid because we didn't do as well as you did and it's really big headed. We seriously don't need that crap before an exam, don't listen we are all going to get what we want and need!! Ps. I was 2 marks off an A overall soooo not that stupid
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    (Original post by potato cell)
    I am also resitting the paper lol.
    No! Not you!!! Hahaha, the *other* guy 😂
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    (Original post by bethey180)
    It's just so horrible to come onto a thread and basically say all of us resitters are stupid because we didn't do as well as you did and it's really big headed. We seriously don't need that crap before an exam, don't listen we are all going to get what we want and need!! Ps. I was 2 marks off an A overall soooo not that stupid
    Just ignore the troll, he probably doesnt even do Chemistry haha
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    (Original post by man i)
    bro i wish i knew how to get full marks, i've been doing past papers to the point where i know the mark schemes but considering the way last years exam was and that this year only A2 students are doing the exam, grade boundaries gonna be high and questions are gonna end up having A2 style to them.
    My teacher is an Aqa chemistry marker and also writes the papers too, apparently all the papers are written two years in advance so when this paper was written they wouldn't have know it would just be A2 students sitting it. It will be equally as hard as other years
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    can some help me for one of the questions it the one about the ratio of isotopes

    B-10 and B-11 has a molecular mass of 10.8 whats the ratio of the isotopes?

    ive been looking and the mark scheme and still not been able to get it.
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    Dang it's tomorrow...
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    Aaaahhhhhhhhhhh -_-
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    (Original post by man i)
    can some help me for one of the questions it the one about the ratio of isotopes

    B-10 and B-11 has a molecular mass of 10.8 whats the ratio of the isotopes?

    ive been looking and the mark scheme and still not been able to get it.
    it just about the ratio how much of each do you need to get that 10.8 so obviously you need more of B-11 as the molecular mass is closer to it in this case its very simple to see you need 20% of B-10 and 80% of B-11
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    (Original post by man i)
    can some help me for one of the questions it the one about the ratio of isotopes

    B-10 and B-11 has a molecular mass of 10.8 whats the ratio of the isotopes?

    ive been looking and the mark scheme and still not been able to get it.
    We were taught to set it up like an equation bc it makes it easier to understand:

    10.8 = (10x) + (11y)

    Where the first Bracket represents 'B-10' and the second bracket represents 'B-11'.

    Once you've done that then you play trial and error.

    x + y must be equal to 1.

    So you could first substitute x as 0.1, then y as 0.9 - If it doesn't equal to 10.8 then you work up to the next number e.g.

    0.2 as x, 0.8 as y
    0.3 as x, 0.7 as y

    etc

    Until you get the value on the left hand side.

    In this scenario, x will be 0.2 and y will be 0.8 because:

    10.8 = (10x) + (11y)

    therefore

    10.8 = (10(0.2)) + (11(0.8))

    therefore

    10.8 = 2 + 8.8

    Then once you've figured that out, you just times each of the values by 100 to get it as a percentage. So it'll be 20% and 80%.
    ..

    Does that make sense? >.< Sorry if I didn't manage to explain it v well.
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    (Original post by Anon_98)
    We were taught to set it up like an equation bc it makes it easier to understand:

    10.8 = (10x) + (11y)

    Where the first Bracket represents 'B-10' and the second bracket represents 'B-11'.

    Once you've done that then you play trial and error.

    x + y must be equal to 1.

    So you could first substitute x as 0.1, then y as 0.9 - If it doesn't equal to 10.8 then you work up to the next number e.g.

    0.2 as x, 0.8 as y
    0.3 as x, 0.7 as y

    etc

    Until you get the value on the left hand side.

    In this scenario, x will be 0.2 and y will be 0.8 because:

    10.8 = (10x) + (11y)

    therefore

    10.8 = (10(0.2)) + (11(0.8))

    therefore

    10.8 = 2 + 8.8

    Then once you've figured that out, you just times each of the values by 100 to get it as a percentage. So it'll be 20% and 80%.
    ..

    Does that make sense? >.< Sorry if I didn't manage to explain it v well.
    talk about proof daymm
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    (Original post by Anon_98)
    We were taught to set it up like an equation bc it makes it easier to understand:

    10.8 = (10x) + (11y)

    Where the first Bracket represents 'B-10' and the second bracket represents 'B-11'.

    Once you've done that then you play trial and error.

    x + y must be equal to 1.

    So you could first substitute x as 0.1, then y as 0.9 - If it doesn't equal to 10.8 then you work up to the next number e.g.

    0.2 as x, 0.8 as y
    0.3 as x, 0.7 as y

    etc

    Until you get the value on the left hand side.

    In this scenario, x will be 0.2 and y will be 0.8 because:

    10.8 = (10x) + (11y)

    therefore

    10.8 = (10(0.2)) + (11(0.8))

    therefore

    10.8 = 2 + 8.8

    Then once you've figured that out, you just times each of the values by 100 to get it as a percentage. So it'll be 20% and 80%.
    ..

    Does that make sense? >.< Sorry if I didn't manage to explain it v well.
    no thats amazing thank you i was just trying to find a way of doing it, that actually make sense.
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    (Original post by man i)
    no thats amazing thank you i was just trying to find a way of doing it, that actually make sense.
    Ah great, you're welcome.
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    (Original post by Anon_98)
    We were taught to set it up like an equation bc it makes it easier to understand:

    10.8 = (10x) + (11y)

    Where the first Bracket represents 'B-10' and the second bracket represents 'B-11'.

    Once you've done that then you play trial and error.

    x + y must be equal to 1.

    So you could first substitute x as 0.1, then y as 0.9 - If it doesn't equal to 10.8 then you work up to the next number e.g.

    0.2 as x, 0.8 as y
    0.3 as x, 0.7 as y

    etc

    Until you get the value on the left hand side.

    In this scenario, x will be 0.2 and y will be 0.8 because:

    10.8 = (10x) + (11y)

    therefore

    10.8 = (10(0.2)) + (11(0.8))

    therefore

    10.8 = 2 + 8.8

    Then once you've figured that out, you just times each of the values by 100 to get it as a percentage. So it'll be 20% and 80%.
    ..

    Does that make sense? >.< Sorry if I didn't manage to explain it v well.
    Oh you utter darling. Thank you so much.
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    (Original post by Kattkin)
    Oh you utter darling. Thank you so much.
    No problem!
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    anyway goodluck guys hope you all smash the exam.
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    Can someone please explain to me the answer to question 5g?

    http://filestore.aqa.org.uk/subjects...1-QP-JUN13.PDF

    Nb: the answer is 'Second' but I can't work out why.
 
 
 
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