Mokk Posted May 17, 2013 Report Share Posted May 17, 2013 Thoughts? Was alright for me, did question 6 on P2 Section B. Section A on P2 was very manageable.Bit of debate in my class on the final question, the one on precision and accuracy. I said it was both, but I'm unsure given how subjective a question it was. Reply Link to post Share on other sites More sharing options...
Faleleevka Posted May 17, 2013 Report Share Posted May 17, 2013 Wow, I actually said it was neither for the last question... Cause the accurate thermometer showed 2.30, and none of the values hit that figure - so, they weren't accurate. And there was a great difference between 2.2 and 2.6, so they weren't precise. That was my logic at that moment, but true - the question is very subjective I guess... Reply Link to post Share on other sites More sharing options...
Mokk Posted May 17, 2013 Author Report Share Posted May 17, 2013 Wow, I actually said it was neither for the last question... Cause the accurate thermometer showed 2.30, and none of the values hit that figure - so, they weren't accurate. And there was a great difference between 2.2 and 2.6, so they weren't precise. That was my logic at that moment, but true - the question is very subjective I guess...Yeah, the majority in my group actually went for precise but not accurate - very subjective, I can see it being one of those questions for which IB takes more than one answer, or just scraps altogether. 1 Reply Link to post Share on other sites More sharing options...
Jamal102 Posted May 17, 2013 Report Share Posted May 17, 2013 I talked to my chem teacher. He said the first result which was like 2.6 is just a preliminary test and the other numbers like 2.4 2.2 and whatever where in proximity of eachother by 0.2 and thus its precise but inaccurate.What about the meniscus for P2. Why did you say it was measured from the top or bottom? Reply Link to post Share on other sites More sharing options...
Christina perera Posted May 17, 2013 Report Share Posted May 17, 2013 What was the answer to the hess law question? was it something like -107? Reply Link to post Share on other sites More sharing options...
RatherLong Posted May 17, 2013 Report Share Posted May 17, 2013 What was the answer to the hess law question? was it something like -107?Yeah, something like that as far as I recall.What did you get for the titration question at the start of Paper 2? Reply Link to post Share on other sites More sharing options...
Jamal102 Posted May 17, 2013 Report Share Posted May 17, 2013 there were many parts for that titration.first that it was a systematic error obviously.and one of the answers for MnO2I said that maybe Mn04 it wasn't reduced/oxidized (cant remember) properly because they needed to stir for a longer period of time. Reply Link to post Share on other sites More sharing options...
Hailzter Posted May 18, 2013 Report Share Posted May 18, 2013 Paper 1 was amazing except for the last question, for which everyone in my class had a different answer.Apart from the first question, I found the rest of section A from Paper 2 pretty easy. How the hell are we supposed to know why he measured the meniscus from the top and not the bottom?! Did anybody else get the Hess's law answer as -106? It was worth 4 marks!I did question 6 from section B. For the enthalpy change, I got it as a value in the -100s.. I think around -180 or something, I don't really remember. And what compound is formed when ethanol becomes acidic? I just wrote Carbon Dioxide, wild guess! Reply Link to post Share on other sites More sharing options...
DP4eva Posted May 18, 2013 Report Share Posted May 18, 2013 Yes, the answer to the Hess's Law question was -107KJ. Also i felt the calculations in section A were a bit confusing, but everything else seemed fine.Am i the only one who picked organic in Section B (Q7)? Seemed pretty straightforward to me 1 Reply Link to post Share on other sites More sharing options...
Hailzter Posted May 18, 2013 Report Share Posted May 18, 2013 Are you sure it was -107? I think I got -106.. I multiplied was of the enthalpy changes by 3, one of them by 4 and I reversed the sign for the one which had around a 2200 change in enthalpy. I'm going to be so pissed if I've made a calculation error, it might cost me my 7! Do you think grade boundaries will increase or decrease? Reply Link to post Share on other sites More sharing options...
DP4eva Posted May 19, 2013 Report Share Posted May 19, 2013 (edited) Im pretty sure it will stay around the same, or may increase slightly cause this was definitely easier than may 2012 which had an insane section A question..My guess is between 76%-78% overall for a seven Edit - Hailzter, yeah it could be -106 my memory is fading slightly (Yes i did multiply one by 3 and one by 4 and reversed the sign aswell) Edited May 19, 2013 by DP4eva Reply Link to post Share on other sites More sharing options...
Matteo Gilliotti Posted May 20, 2013 Report Share Posted May 20, 2013 Yes, the answer to the Hess's Law question was -107KJ. Also i felt the calculations in section A were a bit confusing, but everything else seemed fine.Am i the only one who picked organic in Section B (Q7)? Seemed pretty straightforward to meHey I chose that question in section B!! I have a serious doubt. It said first that the alkene reacted wiht HBr (i guess) and was transformed into a secondary alcohol (but-2-ol). Then, it said that that alcohol reacted in reflux with some catalyst containing Cr, and actually a secondary alcohol does not need reflux to be oxidized into a ketone. Just heat, catalyst. But it said in reflux!! And the only reaction that needs reflux is to transform a primary alcohol into a carboxylic acid! So wtf. I put that it transformed into a carboxylic acid. What did you put?ps: did you put mechanism Sn1? I went for precise and accurate. Because if you apply the formula of percentage error, they give actually pretty accurate results (no more error than 15%), and that is really accurate. And well, precise because they were really close to each other. Reply Link to post Share on other sites More sharing options...
DP4eva Posted May 21, 2013 Report Share Posted May 21, 2013 Yes, the answer to the Hess's Law question was -107KJ. Also i felt the calculations in section A were a bit confusing, but everything else seemed fine.Am i the only one who picked organic in Section B (Q7)? Seemed pretty straightforward to meHey I chose that question in section B!! I have a serious doubt. It said first that the alkene reacted wiht HBr (i guess) and was transformed into a secondary alcohol (but-2-ol). Then, it said that that alcohol reacted in reflux with some catalyst containing Cr, and actually a secondary alcohol does not need reflux to be oxidized into a ketone. Just heat, catalyst. But it said in reflux!! And the only reaction that needs reflux is to transform a primary alcohol into a carboxylic acid! So wtf. I put that it transformed into a carboxylic acid. What did you put?ps: did you put mechanism Sn1? I went for precise and accurate. Because if you apply the formula of percentage error, they give actually pretty accurate results (no more error than 15%), and that is really accurate. And well, precise because they were really close to each other. Yes it was an Sn1 mechanism and I forgot what I did for the secondary alcohol question, but I think i put carboxylic acid as well because that was the only thing which made sense. (Could be a problem with the question, im not so sure).I put accurate, but not precise but the question was so subjective, how exactly are we to know whether those numbers are precise or not (Because it all depends on by how much u define precise to be as). Reply Link to post Share on other sites More sharing options...
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