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    (Original post by andersson)
    The H+ ions move to the cathode (because it is negative so they are attracted to it) and accept electrons from the cathode. Now, two hydrogen atoms will really want one more electron in their outer shell to make it complete, so they will bond covalently (share an electron) and become H2.
    Thank you, it seems obvious now you've said it and I feel a bit stupid
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    (Original post by Red Fox)
    At the bottom of page 85 in the CGP revision guide it says "Electrolysis of hydrochloric acid or ethanoic acid produces H2 because they both produce H+ ions". I don't really understand this despite it sounding basic. I might have missed something but can someone explain this please.
    Electrolysis causes hydrochloric acid and ethanoic acid to "break down" into ions. If you look at the chemical formula for hydrochloric acid (HCl) and ethanoic acid (CH3COOH), they both contain a Hydrogen atom (underlined).

    Therefore, both acids release H+ ions which are released during electrolysis and because Hydrogen is diatomic (meaning that it always travels around in pairs), 2 H+ ions are needed and bond to form H2 which is released at the negative cathode.

    Hope this helps
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    (Original post by BP_Tranquility)
    Electrolysis causes hydrochloric acid and ethanoic acid to "break down" into ions. If you look at the chemical formula for hydrochloric acid (HCl) and ethanoic acid (CH3COOH), they both contain a Hydrogen atom (underlined).

    Therefore, both acids release H+ ions which are released during electrolysis and because Hydrogen is diatomic (meaning that it always travels around in pairs), 2 H+ ions are needed and bond to form H2 which is released at the negative cathode.

    Hope this helps
    Thanks
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    I got 101/140 UMS marks which was a B last year, I got 31/48 in my coursework which is a high C maybe a B, but if it was a C, and I got a C in the exam Thursday do you think I could end up with a B overall?


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    Finished the revision guide now
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    Be honest with me, guys.

    In this upcoming Chemistry Exam, what would be the RAW mark for a B?

    In addition, what grade does 120/160 equate to?

    Sorry about the laziness but this Graphics exam has totally taken the energy out of me despite it going well.
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    (Original post by IHTWFR)
    Be honest with me, guys.

    In this upcoming Chemistry Exam, what would be the RAW mark for a B?

    In addition, what grade does 120/160 equate to?

    Sorry about the laziness but this Graphics exam has totally taken the energy out of me despite it going well.
    :dontknow:

    And 120/160 is a B. (middle B)
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    I better get an A* because today is the hardest I've ever worked in my life I've done like 5 hours of revision.
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    Out of curiosity, during metallic bonding, why don't the closely packed electrons and positive ions repel away from each other?


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    (Original post by BP_Tranquility)
    Out of curiosity, during metallic bonding, why don't the closely packed electrons and positive ions repel away from each other?


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    Imagine you introduce a positive ion and a negative ion, they attract, then you introduce a second pair, with a positive and negative end. I don't know but I assume two together sort of flip round to arrange themselves like magnets do.

    So basically all the positive ions and all the negative ions repel at first, and then as positives and negatives join up they're able to join with other pairs, which are then able to join with other quads.. etc

    That might not be right but I think it makes sense?
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    (Original post by L'Evil Fish)
    :dontknow:

    And 120/160 is a B. (middle B)
    I thought that as well. I need 157/160 for an A* which is possible but the exam is on Thursday - It always turns out I fluke Chemistry somehow
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    (Original post by IHTWFR)
    I thought that as well. I need 157/160 for an A* which is possible but the exam is on Thursday - It always turns out I fluke Chemistry somehow
    Doable
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    i missed out around 4/5 pages last year for my bio exam..still got 140

    definitley do able!!


    (Original post by IHTWFR)
    I thought that as well. I need 157/160 for an A* which is possible but the exam is on Thursday - It always turns out I fluke Chemistry somehow
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    (Original post by IHTWFR)
    I thought that as well. I need 157/160 for an A* which is possible but the exam is on Thursday - It always turns out I fluke Chemistry somehow
    Like the others said this is very achievable. I got 137 in Bio and Chem last year with minimal revision. I need 153 on this Chem exam.
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    (Original post by IHTWFR)
    Be honest with me, guys.

    In this upcoming Chemistry Exam, what would be the RAW mark for a B?

    In addition, what grade does 120/160 equate to?

    Sorry about the laziness but this Graphics exam has totally taken the energy out of me despite it going well.
    Erm well when we did a specimen paper for this new exam last week, it was 51 for an A*, 42 for an A. Also, these will be similar to the actual grade boundaries according to our teacher, so a B will probably be around 33ish?


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    Wat mark was the exam out of?
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    (Original post by AR-13)
    Wat mark was the exam out of?
    If you mean last year, it was 75 raw marks and 140 UMS. This year it is 85 raw marks and 160 UMS.
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    Hi, can someone please explain electrolysis in the simplest way they can cause I don't understand it whatsoever? Thanks.
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    (Original post by AsianNoodles)
    Hi, can someone please explain electrolysis in the simplest way they can cause I don't understand it whatsoever? Thanks.
    Okay:

    Positive = Anode
    Negative = Electrode

    Electrolysis is breaking down through electricity.

    I'll start with the easiest to understand.

    Molten Lead Bromide = PbBr(2)

    It's an ionic bond made up of ions:
    Pb2+ and Br-

    So these are now molten and flowing freely.

    The Pb2+ is positive and so is attracted to the cathode. It gains 2 electrons there and becomes lead (no charge). Lead is reduced.

    The Br- ions are negative and are attracted to the anode. It gives an electron to the anode and becomes Br (no charge). It is oxidized.

    Yeah?
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    (Original post by cameron262)
    Imagine you introduce a positive ion and a negative ion, they attract, then you introduce a second pair, with a positive and negative end. I don't know but I assume two together sort of flip round to arrange themselves like magnets do.

    So basically all the positive ions and all the negative ions repel at first, and then as positives and negatives join up they're able to join with other pairs, which are then able to join with other quads.. etc

    That might not be right but I think it makes sense?
    Ah, I see thanks


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