Chemistry
For Chemistry Discussions
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- 7 replies
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So I'm designing a lab and i'm trying to test the solubility differences between methanol, ethanol, propanol, and butanol. My current experiment is taking 100 ml of water and pouring it into the reaction vessel. I then take 2 ml of the alcohol and pour 2 drops of blue food coloring into it. I then put the reaction vessel with water on a hot plate (with heat OFF, JUST USED FOR STIRRING). I then pour the alcohol into the water and set the stir to a low setting. The only problem I have is that when i test the experiment, the more carbon atoms there are, the faster the food coloring disperses (to the bottom). Shouldn't it be the opposite way around as in the mixtures with th…
Last reply by genepeer, -
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I'm planning to "Investigate the effects of potassium permanganate in acidc, neutral and basic media". I found some info about it on the net: http://www.siraze.net/chemistry/sezennur/subjects/experiment/036.pdf http://81.207.88.128/science/chem/exps/mini-expl/index.html When I look at the assessment criteria, however, it seems it will be a bit hard to "define a problem", as I'm merely investigating the effects. Also, I'm unsure of how to collect "sufficient relevant data". It seems most of the observations in the experiment will be qualitative observations. I guess i could find a way to see if the pH changes in the solution, but then I would have to find a very accurate i…
Last reply by larry, -
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hi, i need the values of lattice enthalpies for LiOH, NaOH and KOH for my chemical investigation. i searched the net, booklets and all my textbooks - no effect. i would be thankful for any help
Last reply by virginia.w, -
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We were told to do a experiment of a factor that affects rust. I choose to do pH and placed iron nails in solution of pH 3, 5, 7, 9, and 11. I used HCl to make up the acidic solutions and NaOH to make up the basic solutions. What little research I could find said that acidic solution should cause the greatest corrosion and basic solution should minimise corrosion. If only my results showed that... Basically the nails in pH 3 solution hardly rusted at all and the nails in pH 11 solution rusted the most. If anyone has any explanation of why this happened or could lead me to any sources of why this happened it would be really appreciated. I know the results I got are probabl…
Last reply by Drake Glau, -
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I was wondering what is the best process to measure the CaCo3 (calcium carbonate) content of paper. I was thinking of making a reaction between CaCO3 with HCl. From that, how can I measure the CaCO3 (from the fact that it is also the limiting reagent)?
Last reply by Drake Glau, -
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Is there any way one can access the IB Chemistry Question Bank or Lab Bank?
Last reply by LMS, -
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Its due on Monday, and its a calorimetry lab. My teacher didn't give us any outlines or examples or anything, she just said it would be graded on "data processing and conclusion and evaluation" I don't have a clue about where to start or anything for the lab report, does anyone have anything that would help? Also, I have a graph with temperature vs. time. I'm not sure whether to extrapolate the graph to get the peak temperature, as my teacher told me not to. But it makes sense to do so, and it says in my study guide to do so.
Last reply by dessskris, -
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Hello, I just started IB this year and at first felt confident for HL Chemistry, however, I was quick to learn that HL Chem is NOT a "walk in the park". Recently, I took a stoichiometry quiz (My teacher used previous IB questions) and epically failed it! I completely and utterly blanked and didn't even understand the questions asked (I couldn't answer ANY of them). If it is possible, can anyone give me any feedback on the course and what to expect of it? Is topic one the most math oriented topic? If so, are the other topics somewhat easier to comprehend? I really like Chemistry and desire to do well in the class and more importantly in the exam (in 2012)!
Last reply by Drake Glau, -
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Hii Could anyone please give me an outline how to design this experiment ? - The strength of different acids or bases ( Electrical conductivity)
Last reply by dessskris, -
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Hi guys, i am having troubles with chem options. My teacher taught option A Analytical chemistry and option E Environmental. Personally, I feel that I can't handle option A, its something that I can't absorb . Im thinking about doing an option that is not taught for the Nov exam this year. Is there any suggestion which one should I do? Thanks in advance guys
Last reply by Sublime Sunshine, -
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Hi guys So I have a design lab due tomorrow and I don't know how to measure the resistance of paint to dichloromethane. Second, does anyone know HOW dichloromethane "strips" paint? Is there a name for it? Like.. corrosion? Thank you so much!! -Yena
Last reply by Sandwich, -
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I have to design an experiment to do with paper chromatography.. The independent variable is up to us but it has to affect the Rf value of whatever we are testing.. I'm stuck trying to research what actually affects the Rf value besides from different solvents. Does anyone know if the temperature of the solvent affects the Rf value??? A source would be perfect, but not necessary. Thanks so much. xxx
Last reply by Sublime Sunshine, -
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Hey there, this is my first IB design lab and i am not sure what am i supposed to do. The topic or research question or whatever you call it is separation of a mixture. I think i am going to do chromatography as the teacher told us that IBO prefers quantitative labs more than qualitative labs. (I guess chromatography would have a lot of data with all the RF values and things. I'm still thinking on which mixture i would do my chromatography on. I guess it would be nice to use something common such as food coloring as the RF values would be easier to find. But are there any other better techniques? I know distillation would be a good one but what kind of data could i take…
Last reply by Tilia, -
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Hi. I'm using the formula PV = nRT in my latest IA, and I got the atmospheric pressure values from the Australian Bureau of Meteorology website. (http://www.bom.gov.au/) I'm pretty sure there's no uncertainty listed on the website, but I don't think the uncertainty can just be 0, either. What should I do? Can I just put 0 and make a note that it's because it wasn't given?
Last reply by Tilia, -
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I recently handed my Chemistry IA's in, and I think they were just sent off for moderation. I got a good mark from my teacher (42/48) but I am really certain that I will get moderated down. The reason is that in one of my pracs, in the conclusion and evaluation, I had to use an internet source to explain why something occurred in a prac (it was way beyond my chemistry level). I did source it, but I am unsure as to whether or not this is acceptable to do? I know that there is no point in worrying but I guess i'm just curious lol
Last reply by Sublime Sunshine, -
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I'm supposed to do the design of a lab investigating one aspect of esterification. Strangely enough, we haven't covered the topic yet. That's why I have no idea what research question I should choose. Does investigating the rate of reaction influenced by different amounts of sulfuric acid make any sense? Is it sensible to focus on the role of temperature needed to heat an alcohol with a carboxylic acid? I would be grateful if anyone could help.
Last reply by Mahuta ♥, -
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how do I determine which molecules possesses delocalized pi bonds? H3C=CH-CH3 H3C-CH=CH-CH2-CH=CH-CH2 H3C-CH=CH-CH=CH2 I'm gonna fail the unit test
Last reply by icecreamshake, -
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hi everyone i am taking chemistry sl and this year is the last year for me in ib and it seems for me a bit hard because i dont have a strong background in Chem.could anyone tell me how to catch up and how to get a 7 ?? waiting for any advice
Last reply by Sandwich, -
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I need a topic for my chemistry lab in relation to the air pollution topics we've studied so far. Air pollution smog ozone depletion acid deposition greenhouse effect I'm thinking about using concentrations of sulfuric acid for independent variable but don't know what to test or test it on. too many people in my class are doing neutralization anyone have ideas i could take?
Last reply by xx_jellybeanz_xx, -
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Last reply by x___x, -
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Hey does someone have a list with all the syllabus definitions we need to know for chemistry? Youd be my hero for sharing them
Last reply by watermelon, -
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I'm looking at the pKa of an acid, and I've done all the calculations, but I'm a little uncertain as to how to calculate the uncertainties for log and pH. Is there any chance any one could help or point me in a direction with information on it? For example, I just picked an arbitrary value... pH = 1.23 (+/- 0.05) --> How would I calculate a percentage uncertainty for this? pKa = -log(1.23x10^-6) = 13.6 --> How would I calculate a percentage uncertainty for this? Any help is appreciated!
Last reply by Tilia, -
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I was wondering if anyone has a really useful study site online? For any of the papers. And good luck on the test the next two days!
Last reply by Tilia, -
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Hey, I'm doing chemistry HL and I'm really nervous about my end-of-year exam (i'm in 1st year of IB). Please write down what you think are the best and most effective ways of revising for chemistry to be well prepared...because I spend ages studying for every chem test we have and my marks are still usually pretty average...and i really want to do well on the exam. Thanks
Last reply by Tilia, -
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Hi guys! I need to do a kinetics lab in my chem class and i was thinking of doing it on concentration affecting the rate of reaction and using change in conductivity to prove it. Unfortunately, i can't find a reaction that works. I've tried to google it and it just doesn't come up. If you know of a reaction that would work or have other ideas for the lab it would be very appreciated. =]
Last reply by Dzeb, -
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I'm doing my practice energetics chemistry IA on the reaction between HCl and Sodium Carbonate. I can't seem to find the literature value to compare to for my percentage error...does anyone have a good source i could start looking at?
Last reply by Tilia, -
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can someone please explain the concept of molecular polarity to me? I don't understand how in some cases, the resultant dipoles cancel out the individual dipoles, because sometimes it's pretty clear, but other times it just doesn't make sense to me..
Last reply by FutureIB, -
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This was a 2 part question. Part i Draw the 2 possible Lewis structures of N3H. Part ii Predict the N-N-N and H-N-N bond angles in each case and give your reasoning. This is the answer scheme: I successfully drew them both but I don't understand the bond angles part. Firstly for the N-N-N one i don't get why it is 180 because there is a lone pair on the first N? do you disregard lone pairs if they're not on the centre atom? Also for I N-N-H i don't understand why there are THREE charge centres? There does not appear to be any a lone pair on the centre N of N-N-H?..
Last reply by Tilia, -
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QUESTION ONE Write balanced equations to represent the formation of the following compounds, starting with T2 or T20 NT3: 3T2+N2-->2NT3 NaOT: i don't know how to do this one could some one help me out please? T2O + 2NA ---> 2NaOt? QUESTION TWO Chlorine exists as two isotopes, Cl-35 and Cl-37. The ram of chlorine is 35.45 Calculate the percentage abundance of each isotope.
Last reply by IBer_101, -
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Which compound, when dissolved in aqueous solution, has the highest pH? A. NaCl B. Na2CO3 C. NH4Cl D. NH4NO3 I am really weak at these kind of question. Probably it is just my pure disgust and abortion towards Acids and bases
Last reply by x___x, -
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Does anybody know the grade boundaries/mark schemes for SL Chem Paper 3 in 2009?
Last reply by CommeDesEnfants, -
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Hi, well I take HL chemistry and I want to at LEAST get a level 4...my course work is a level 5/6 and well how many marks in papers 1, 2, and 3 would I need approximately to get a level 4? I'm really scared I'm going to fail this exam ...I've been trying so hard, doing past papers and everything but it doesn't seem to go in...and I am really freaking out and don't know what to do...I have studied it's just that Chemistry doesn't seem to want to stick in my head...any ideas on how to help me remember a few things in the syllabus? I really don't want to fail and I'm starting to really freak out here...one the options I can get a level 5/6 (did in the mocks) it's ju…
Last reply by master135, -
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I was wondering if you can do an option on the exam that you weren't technically prepared for by the teacher himself, who instead pursued another option unit. In Chemistry, I'd like to do the biochemistry option because I already have knowledge in that from Biology. I have textbooks that would allow me to prepare adequately for the chemistry portion. However, my teacher wants to do another option - perhaps further organic chemistry, which already sounds daunting and undesirable in comparison to biochem. So, on Chem Paper 3, could I just do the biochem option?
Last reply by KLSmash, -
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I did REALLY badly on my Chemistry lab mark (20/48) and I was wondering what would be the highest mark I can get? I asked my teacher and she said a level 6 but would that only apply if I got a level 7 on all 3 papers?
Last reply by Tilia, -
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Blahhh. Okay so the thing is I have seen at least 3 syllabus, all different, so I'm still not sure about what is/isn't going to be asked. For example, buffers. Or the mass spectometer? Which my study guide qualifies as HL, but our teacher gave us a bunch of papers on it? Not to mention there were a couple of questions on it on past papers as well. Anyone knows what subjects were taken out of the syllabus or added, and that are going to be in this year's exams? :3
Last reply by lolocakes, -
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So with a week to go until the SL chem exam, I was flipping through the syllabus and taking notes based on all the guidelines. Theoretically, that's all we need to know, right? But today I was talking to a friend of mine who'd started on past practice exams, and he mentioned that topics like entropy and buffers, which were not mentioned at all in the syllabus, were on the exams. Anyone else encounter this? Could we try to compile a list of things that are missing from the syllabus?
Last reply by Addy, -
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I am extremely bad at constructing energy cycles for Hess's law questions...I always can't work out the balancing of all the equations. Can anyone give me some help? Or give me a link that would provide some help on this topic? It would be much appreciated. Thanks.
Last reply by masochist, -
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I'm doing a lab on the reaction between calcium carbonate and HCl. My independant variable is the mass of calcium carbonate. So basically, I add in different masses of CaCO3 to show that more CaCO3 = higher temperature therefore higher enthalpy change until CaCO3 becomes limiting reagant. However, I still need to calculate the enthalpy change for stuff. And I'm supposed to do it like this: (e.g. from a previous lab using different chemicals.) by plotting the temperature and extrapolating the initial temperature to use in enthalpy change calculations. But for some reason something WEIRD happens with Calcium Carbonate and HCl. Though the higher masses of CaCO3 (near and po…
Last reply by masochist, -
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Does anyone know where I can find a soft copy of the chemistry syllabus the new one?
Last reply by scstdnt, -
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Hi, this is a little bit last minute so if you know the answer, please reply asap! My experimental data for this experiment was off so I'm not exactly sure which direction to go. The reaction between sodium thiosulphate and hydrochloric acid is Na2S2O3 + 2HCl → 2NaCl + S + SO2 + H2O I think, but it also has something to do with this: "To demonstrate the concept of reaction rate in chemistry classes. The thiosulfate ion can decompose into the sulfite ion and a colloidal suspension of sulfur, which is opaque. The equation for this acid-catalysed reaction is as follows: S2O32−(aq) → SO32−(aq) + S(s)" [from wikipedia] What I'm looking for is the rate equation, in the form: ra…
Last reply by Daedalus, -
- 4 replies
- 786 views
Which would be more desirable to self-study in a relatively short, 3-4 week time frame: Option B, Biochemistry, or Option G, Further Organic Chemistry? I hear that both of them are rather difficult, but the syllabus objectives for Option G actually look somewhat shorter to me in comparison to B. On the flip side, Option B seems to contain a lot of memorization of molecular structures and the such. Anybody with any past experience in any of these two options care to share their opinion? My other option is Option D, medicine and drugs.
Last reply by CommeDesEnfants, -
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I'm having a lot of trouble understanding this and I've been trying to figure it out for days. I completely understand Hess' law I just have no idea how to apply it in various scenarios. How do I draw the triangle? How do I split up the equation? When and where does the arrow point up or down? So far I understand that there are 4 types of things that we've learned about that we need to apply the Hess' Law triangle to: - standard enthalpy of formation - standard enthalpy of combustion - standard enthalpy of atomisation - bond enthalpies but i've watched so many videos/read so much stuff on the subject most of which i understand while i'm watching it but i don't know WHY an…
Last reply by masochist, -
Molecule Modelling Software - Chemistry
by Guest IB_procrastinator- 6 replies
- 1.1k views
This is probably a side question, but does anyone know any good softwares to use to model molecules? Especially the organics.
Last reply by 9d9, -
- 3 replies
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For the chemistry internal I was told today the raw data that your represent in the table for Aspect 1 of DCP needs to be in the same units as the measuring equipment. I was just wishing to clarify this point. Here are some examples: 100g (measured using balance in grams) cannot be put in the table as 0.100kg? 100 degrees Celsius (using thermometer) cannot be put in the table as 373 Kelvin? Cheers Lance H
Last reply by Austin Glau, -
- 2 replies
- 611 views
anyone know what it is?
Last reply by 9d9, -
- 1 reply
- 573 views
Could someone give me a detailed description of what they are?
Last reply by Sonneteer_Trombonist, -
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- 829 views
I'm kind of confused on how it works... I get how the electrophiles attack the places with higher electron density but I don't understand how the electron density changes. This is what I know so far, so please help me out. X) +I effect results in 2,4,6 directives because it pushes the electron density down into the benzene ring towards the 2,4,6 positions and increases electron density there relative to the 3,5 positions And the -I effect pushes the electron density out of the benzene ring? I think it makes the activation energy higher, but what effect does that have on the directive...? The lone pair effect is like the +I effect because it pushes electron density into t…
Last reply by Sandwich, -
- 1 reply
- 775 views
I have to research an element or a compound and answer a few questions about it; I'm stuck on one of the questions. The question is: What are the economic reasons we use copper? Thanks.
Last reply by sweetnsimple786, -
- 2 replies
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Helloo, I'm going some chemistry analisis of data, and the IB data booklet doesn't have the theoretical values/ accepted values for the enthalpy of combustion of: Propan-2-ol Butan-2-ol Octanol Can anybody please tell me where I can find them online or if you have them because I keep finding different values on different websites. Thank youuu
Last reply by Sandwich, -
- 3 replies
- 1k views
For whatever reason, I simply cannot wrap my head around reactivity series. My train of thought begins with, "Okay, so X can oxidize Y, but Y is oxidized by Z... So would X oxidize Z?... Uhhh..." Yeah. Anybody got any tips for this? :/
Last reply by CommeDesEnfants,
