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OCR Salters Chemistry F335 12th June 2013 Exam revision thread Watch

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    (Original post by Pie1213)
    No we've still got oceans to do but apart from that we've gone through all the sections what have you got left to do?

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    Same for me

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    What synoptic stuff comes up the most?
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    We're nearly finished MD and O and literally just starting to bash exam papers now, luckily i've done quite well in my F336 so I'm in a good position for F334/F335
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    we've finished finished the week before half term started. Just did my first practice paper and was one mark off an A! WOOOOO
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    Does anyone have the jan 2013 paper? Can u upload please?
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    Anybody know of any exam style question resources bar past papers ?


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    (Original post by CameronLee)
    Anybody know of any exam style question resources bar past papers ?


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    The Chemical Ideas textbook questions are pretty good
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    anyone else doing f334 aswell? is there a thread for it, I can't find anything ((
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    (Original post by Tikara)
    anyone else doing f334 aswell? is there a thread for it, I can't find anything ((
    Yeah, I'm doing F334 too Revision is going to crank up in the next week or so for that!


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    (Original post by Tikara)
    anyone else doing f334 aswell? is there a thread for it, I can't find anything ((
    I'm doing it too :/
    There is a thread for it, but it's a bit dead. Here's the link anyway: http://www.thestudentroom.co.uk/show....php?t=2307436
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    can anyone explain why is H2SO3 named sulphuric (iv) acid???
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    (Original post by tsr1)
    can anyone explain why is H2SO3 named sulphuric (iv) acid???
    It's sulfuric acid if its dissolved in water or hydrogen sulfate if its not. The number in the brackets tells us the oxidation state of sulfur.


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    (Original post by tsr1)
    can anyone explain why is H2SO3 named sulphuric (iv) acid???
    Expanding on the super121's point above:

    In H2SO4 and H2SO3, sulphur has two different oxidation states, which can be worked out.

    H2SO4:
    Hydrogen nearly always has an oxidation state of +1. As there are two of these, the SO4 anion must have a charge of 2-.
    Oxygen nearly always has an oxidation state of -2. As there are 4 of these, the overall number will be -8 for oxygen. To balance this with sulphur and get an overall charge of the anion to be -2, we need an oxidation state of +6 on the sulphur, as 6-8=-2.

    Therefore: hydrogen sulphate(VI) / Sulphuric(VI) acid.

    H2SO3:
    Hydrogen nearly always has an oxidation state of +1. As there are two of these, the SO3 anion must have a charge of 2-.
    Oxygen nearly always has an oxidation state of -2. As there are 3 of these, the overall number will be -6 for oxygen. To balance this with sulphur and get an overall charge of the anion to be -2, we need an oxidation state of +4 on the sulphur, as 4-6=-2.

    Therefore: hydrogen sulphate(IV) / Sulphuric(IV) acid.
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    (Original post by Harantony)
    Expanding on the super121's point above:

    In H2SO4 and H2SO3, sulphur has two different oxidation states, which can be worked out.

    H2SO4:
    Hydrogen nearly always has an oxidation state of +1. As there are two of these, the SO4 anion must have a charge of 2-.
    Oxygen nearly always has an oxidation state of -2. As there are 4 of these, the overall number will be -8 for oxygen. To balance this with sulphur and get an overall charge of the anion to be -2, we need an oxidation state of +6 on the sulphur, as 6-8=-2.

    Therefore: hydrogen sulphate(VI) / Sulphuric(VI) acid.

    H2SO3:
    Hydrogen nearly always has an oxidation state of +1. As there are two of these, the SO3 anion must have a charge of 2-.
    Oxygen nearly always has an oxidation state of -2. As there are 3 of these, the overall number will be -6 for oxygen. To balance this with sulphur and get an overall charge of the anion to be -2, we need an oxidation state of +4 on the sulphur, as 4-6=-2.

    Therefore: hydrogen sulphate(IV) / Sulphuric(IV) acid.
    very well explained.. thank you
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    does anyone know if NaBH4 reduces carboxylic acids?
    I know it can reduce aldehydes and ketones to their respective alcohols but it doesn't really mention anything about reducing -COOH to a tertiary alcohol
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    also, if people don't have the A2 revision guide and want more exam style questions I can post some up
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    (Original post by Tikara)
    does anyone know if NaBH4 reduces carboxylic acids?
    I know it can reduce aldehydes and ketones to their respective alcohols but it doesn't really mention anything about reducing -COOH to a tertiary alcohol
    I really doubt that they will ever ask about the potential of NaBH4 reducing carboxylic acids. It's nowhere in the data sheet, nor the textbooks, so I shan't worry.

    Plus, remember carboxylic acids come from primary alcohols, as it initially oxidises into an aldehyde, then further oxidation gives you the carboxylic acid.
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    (Original post by abzy1234)
    I really doubt that they will ever ask about the potential of NaBH4 reducing carboxylic acids. It's nowhere in the data sheet, nor the textbooks, so I shan't worry.

    Plus, remember carboxylic acids come from primary alcohols, as it initially oxidises into an aldehyde, then further oxidation gives you the carboxylic acid.
    shiieeet - yeah I completely got that wrong didn't I :P tertiary alcohols don't oxidise silly me thanks vm yeah they won't ask anything on this

    (but searching google did suggest it doesn't and people usually use a slightly different reducing agent)
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    (Original post by Tikara)
    shiieeet - yeah I completely got that wrong didn't I :P tertiary alcohols don't oxidise silly me thanks vm yeah they won't ask anything on this

    (but searching google did suggest it doesn't and people usually use a slightly different reducing agent)
    Yeah once you actually go deeper and deeper into the crazy world of organic chemistry, you get all kinds of weird reagents!

    Stick to our textbooks
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    (Original post by david2457)
    What synoptic stuff comes up the most?
    I just saw this post now!

    But having done loads of the past papers, pretty much anything comes up. You have to be prepared to use your knowledge right from F331; there was this one question that used F331,2,4 content all jumbled up. :/

    Saying that, if you know your chemistry well, you can't go wrong. At the end of the day, chemistry is chemistry; so just make sure you read all over your chemistry notes!
 
 
 
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