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    no, about neutralising the acid in the drink . . . i could describe the titration method, but didnt know the one-marker after it!
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    It was exothermic and the change was 730..which question on neutralising? The one about why wont that be the volume needed to neutralise ascorbic acid (also contains citric)

    KEN

    Take bond energy formed-bond energies broken.

    If that is positive then there is excess energy=heat relased=exothermic.

    If negative then not enough energy=taken in from surroundings=endotheric.

    The specification did not require knowledge of the deltaH format, rather the method above, which is perhaps why you got confused as it is the other way round.
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    What question was that? i dont rememeber it lol
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    I thought that was about why is the results from the titration not the amount needed?
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    I thought it was to do with the citric acid that was also contained ie the results were for both acids. IIRC the question was why is the volume of NaOH incorrect.
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    Ken..im thinking though if you have an excess of NaOH, then it is not neutral (which the question asked) and the amount you have added is therefore not the amount required to neutralise the acid.
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    I got the Bond Energies one to be -730, the minus means it is an exothermic reaction, does it not?
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    ^same

    I put the energy released when new bonds formed is greater than the energy required to break old bonds
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    Its only -ve if you said it was ΔH=-730kj/mol.

    Otherwise its positive to show the exothermic reaction i think.

    Lol for seeing my point look in the cgp books...of course they are prolly wrong
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    David Jones, my answer was genetically identical (well, maybe not genetically) to yours!
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    t-a-r i may be wrong...lol...especially now, at this time, but it is in the cgp guides and my exercise books. Well whats done is done i may have got it wrong, just like i may have misread the question above (although i didnt think i did)...
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    PS Helper
    exothermic = negative
    endothermic = positive

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    If you have black cgp chemistry page 180

    'Since this is energy relesed, then if we wanted to show DeltaH we'd need to put a -ve in front of it to indicate its an exothermic reaction'
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    Yeah, you're correct... but in terms of the question, all it wanted was: "Explain why the reaction is exothermic in terms of bond energies"

    To do this, you can just write: The negative sign indicates an exothermic reaction, as more energy is needed to make/form new bonds than to break old bonds.

    I think we are both correct: you go into more detail though!
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    O right sorry lol yeah i put that more energy is released in forming than went into the new bonds, therefore this excess enegery is given off in the form of heat, hence exothermic.

    Apologies t-a-r...

    What was the question after the titration, was it what ken said or what i said as ive gotten confused now. I thoguht the question was definately 'why is the volume not the volume needed' or something along those lines.
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    It's fine Tim!

    The question was: "Why is so much NaOH placed inside the Burette, even if the neutralisation reaction requires such a little volume" (or something along those lines)!!

    I think this is completely wrong, but i put that: "The experiment could be repeated quickly, as NaOH isn't added at the start of each experiment, there is still the alkali left from the previous reaction"!
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    Wait wasnt it Why is so much placed in if so little is required to neutralise the ascorbic acid? I said because there is also citric acid in the drink as well...ahh well

    O for the record lol the name isnt Tim its Richard...apologies if ive decieved you..ill start signing off Richard and have a name change soon. Apologies
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    lol!!!! Ok, Tim: sorry, Richard!

    Erm, this question confused me slightly 'cos in class we were always told that acid was placed into the burette, this is clearly not the case here.
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    it was MINUS not positive for the exothermic reaction, so your wrong saying it is +730. I too have the cgp books and it makes it quite clear that you say -730, god sake read properly.
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    It is because NaOH damages the glassware, so its just out of good practice lol it doesnt really matter, especially if its hyperthetical speaking.

    I did use methyl orange though instead of phenolpthaleine but again i was unsure whether i was right or not (lol typical TSR question). Turns out methyl orange is an indicator to the the acid-neutral reaction (in the question) rather than an alkaline-neutral reaction as it normally is as the aalkali is normally in flask.

    So what exams have you got left?

    Paul read it through it says to express as energy change its

    new bonds-broken bonds=positive

    To express as deltaH it is broken bonds-new bonds=negative
 
 
 

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