Zangetsu Posted May 13, 2016 Report Share Posted May 13, 2016 Damn for me, I found Paper 1 fine, but I really struggled with Paper 2. I hope the boundaries aren't too high this year... 1 Reply Link to post Share on other sites More sharing options...
Guest SNJERIN Posted May 13, 2016 Report Share Posted May 13, 2016 8 minutes ago, #teamnosleep said: Guys, for the pre-combustion of sulfur dioxide question, will neutralizing with water (which can act as a base) count as correct? Also, for the chemical test for separating compound A and B, would distillation be correct? Are you sure the grade boundaries will be higher this year? Pre-combustion basically means what you can do to remove the sulfur from the the coal before burning the coal. So just adding water to the coal does not really neutralize the sulfur dioxide, as it has not been formed yet. However, if you crush to coal into small pieces and wash it thoroughly with water from a nearby river you would be able to remove the sulfur to some extent. For your second question. I wrote, adding bromine water to separate tubes of each compound and if the bromine decolonizes then we have the alkene A. I do not think distillation can help you to identify which compound is which, since the boiling point of both compounds are very similar, don't you agree ? Reply Link to post Share on other sites More sharing options...
Malino Posted May 13, 2016 Report Share Posted May 13, 2016 My teacher told us that the only acceptable answers were hydrosulfurization for pre combustion and flue-gas desulfurization for post-combustion.. I don't know if it's true or not but he is an ib examiner Reply Link to post Share on other sites More sharing options...
Guest SNJERIN Posted May 13, 2016 Report Share Posted May 13, 2016 2 minutes ago, Malino said: My teacher told us that the only acceptable answers were hydrosulfurization for pre combustion and flue-gas desulfurization for post-combustion.. I don't know if it's true or not but he is an ib examiner Might be true, but that is one way of reducing the sulfur oxide emission. If you search for the net you will most likely find many other methods, so I am not sure about whether IB only accept this answer. BTW, from the question, I remember it says, describe one pre-combustion method, so there are many. Reply Link to post Share on other sites More sharing options...
Dawid Posted May 13, 2016 Report Share Posted May 13, 2016 I have made a fatal mistake in the Paper 2. A lot of questions consisted of moles calculations and when I was calculating molar mass I added atomic number of each element instead of mass number. The worst thing is, I noticed that I'm looking at the wrong numbers in the periodic table a minute before the end of the exam. So becuase of the wrong molar mass I will probably lose all points from questions involving calculations. Well... I hope that at least I will get some points from other papers Reply Link to post Share on other sites More sharing options...
bwf8398 Posted May 13, 2016 Report Share Posted May 13, 2016 I put coal gasification as a pre-combustion way to reduce production of SO2, one of the perks of studying option C, haha. I'm pretty sure IB will accept it. For the oxidation question, I think you had to notice that it was gaining both Hydrogen (which is one definition of reduction) and Oxygen (which is one definition of oxidation), and point out that it couldn't undergo both, which might be implied by the other definition, so oxidation state showed it was clearly being oxidized. Did anyone know why nitrogen oxides don't contribute much to acid deposition? I completely guessed and said it's because they aren't common, but I want to know the real answer. Reply Link to post Share on other sites More sharing options...
oliviariesgo Posted May 13, 2016 Report Share Posted May 13, 2016 7 hours ago, Malino said: Yeah that's true! I had no idea of what the answer was for the pre combustion and post combustion sulfur oxide!! And also the one on the definition of oxidation.. But in the end if you think about it grade boundaries in chem SL are always quite low so I hope they won't go up too much Those are exactly the questions I struggled with! I found paper 1 difficult and I was expecting paper 2 to be a lot harder.. So that was a suprise. Reply Link to post Share on other sites More sharing options...
RebelliousYoshi Posted May 13, 2016 Report Share Posted May 13, 2016 Question with oxidation, the way I approached it was that previous definitions of oxygen meant gaining oxygen/losing hydrogen. The compound gained both and essentially the definitions conflict since it had gained hydrogen rather than losing it. Reply Link to post Share on other sites More sharing options...
Viola.player Posted May 14, 2016 Report Share Posted May 14, 2016 On 13.05.2016 at 3:44 PM, JamVaun said: Oh ye, there was question on allotropes and for some reason I thought Bromine allotropes were Dibromine and Bromide, but realised when I had finished the paper what they wanted (carbon diamond graphene)... This question was a bit confusing since they gave us some equation above the exercise. I wrote allotropes of carbon and then changed it to O2 and O3... Reply Link to post Share on other sites More sharing options...
Malino Posted May 14, 2016 Report Share Posted May 14, 2016 19 hours ago, oliviariesgo said: Those are exactly the questions I struggled with! I found paper 1 difficult and I was expecting paper 2 to be a lot harder.. So that was a suprise. Same! Reply Link to post Share on other sites More sharing options...
Guest beyondtheimagine Posted May 14, 2016 Report Share Posted May 14, 2016 I'm hoping that the grade boundaries aren't too high this year ><" I think I made some silly mistakes on p2 Reply Link to post Share on other sites More sharing options...
The00333 Posted May 14, 2016 Report Share Posted May 14, 2016 How was everyone's paper 3?? I found IR spectroscopy question with O2 vs O3 weirdly challenging. From previous knowledge, I thought O3 was a GHG and not O2. But both gases had super high IR absorbance rates in the graph. Also wasn't it weird that the graph's y-axis was absorbance and not transmittance? The rest of that number was okay though. I found option C pretty easy. There weren't any really challenging questions. Reply Link to post Share on other sites More sharing options...
bwf8398 Posted May 15, 2016 Report Share Posted May 15, 2016 22 minutes ago, The00333 said: How was everyone's paper 3?? I found IR spectroscopy question with O2 vs O3 weirdly challenging. From previous knowledge, I thought O3 was a GHG and not O2. But both gases had super high IR absorbance rates in the graph. Also wasn't it weird that the graph's y-axis was absorbance and not transmittance? The rest of that number was okay though. I found option C pretty easy. There weren't any really challenging questions. I was fine with that one, but I had some different problems. O2 had high UV absorbance, which showed it wasn't a greenhouse gas, so I thought that part was fine. I butchered the transesterification reaction in Option C, haha, but I'm probably not the only one. Other than that, Option C was pretty easy. I also feel like knowing option C made part A of paper 3 easier, which was a pleasant surprise. I had a little trouble with question 2 in Part A because my school didn't have resources to do a titration lab, but I think I hit most of the relevant points. I had no clue about the last question though about why different students would get vastly different results. Other than those minor things, Paper 3 went very well for me. Reply Link to post Share on other sites More sharing options...
The00333 Posted May 15, 2016 Report Share Posted May 15, 2016 2 hours ago, bwf8398 said: O2 had high UV absorbance, which showed it wasn't a greenhouse ga Ahh, that makes much more sense! At least the number was only /2 >< Reply Link to post Share on other sites More sharing options...
JamVaun Posted May 15, 2016 Author Report Share Posted May 15, 2016 12 hours ago, bwf8398 said: I was fine with that one, but I had some different problems. O2 had high UV absorbance, which showed it wasn't a greenhouse gas, so I thought that part was fine. I butchered the transesterification reaction in Option C, haha, but I'm probably not the only one. Other than that, Option C was pretty easy. I also feel like knowing option C made part A of paper 3 easier, which was a pleasant surprise. I had a little trouble with question 2 in Part A because my school didn't have resources to do a titration lab, but I think I hit most of the relevant points. I had no clue about the last question though about why different students would get vastly different results. Other than those minor things, Paper 3 went very well for me. I think the last question on part a (the one about different results) was because bromthynel blue only chnges colour ebtween 6.00 and 7.6 pH...thats what I put and most of my class Reply Link to post Share on other sites More sharing options...
#teamnosleep Posted May 15, 2016 Report Share Posted May 15, 2016 On 5/13/2016 at 10:14 PM, Haitham Wahid said: Pre-combustion basically means what you can do to remove the sulfur from the the coal before burning the coal. So just adding water to the coal does not really neutralize the sulfur dioxide, as it has not been formed yet. However, if you crush to coal into small pieces and wash it thoroughly with water from a nearby river you would be able to remove the sulfur to some extent. For your second question. I wrote, adding bromine water to separate tubes of each compound and if the bromine decolonizes then we have the alkene A. I do not think distillation can help you to identify which compound is which, since the boiling point of both compounds are very similar, don't you agree ? I didn't think of that in the exam room . They're both isomers right? Reply Link to post Share on other sites More sharing options...
#teamnosleep Posted May 15, 2016 Report Share Posted May 15, 2016 Hahahahaha for the different results question I wrote the presence of systematic and random errors... I guess I'm screwed now Reply Link to post Share on other sites More sharing options...
oliviariesgo Posted May 15, 2016 Report Share Posted May 15, 2016 16 hours ago, The00333 said: How was everyone's paper 3?? I found IR spectroscopy question with O2 vs O3 weirdly challenging. From previous knowledge, I thought O3 was a GHG and not O2. But both gases had super high IR absorbance rates in the graph. Also wasn't it weird that the graph's y-axis was absorbance and not transmittance? The rest of that number was okay though. I found option C pretty easy. There weren't any really challenging questions. yeah, the graph confused me and I def put the wrong answer for that question;/ Option D was a breeze for the most part!! Reply Link to post Share on other sites More sharing options...
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