Chemistry
For Chemistry Discussions
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Hey people, I've been away for a while. The good thing is that I'm back and I'm willing to help any Chemistry student with their problems or doubts. I'll be glad to help you with questions regarding lab reports, designs, theory or even on how to approach the actual paper. I hope to be useful. Thanks in advance. Regards
Last reply by IBchemistry, -
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This thread could be used for the new syllabus IA from 2016 onwards. Please note that I cannot help individual students with their IA. The choice of topic should be your own work so please do not ask for suggestions for your IA. The following information is taken from the May 2015 subject report (I'm sure it is copyrighted to the IB, but I see no harm in sharing it with IB students). Research question: Encourage students to choose a research question that has a degree of challenge, is of interest to them and one where they do not know at the outset what the outcome will be.A good research question will probably try to determine a trend or relationship. Students shou…
Last reply by IBsciencewhiz, -
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Here are the links to my website and YouTube channel. I have a full range of videos for both SL and HL topics including options A, B, C and D. Website: http://www.msjchem.com/ YouTube channel: https://www.youtube.com/user/mikesugiyamajones Option A: Option B: Option C:
Last reply by Tragic Survival Chances, -
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My teacher told me that an IB study guide would be very helpful going through Chemistry and I started looking online for a book. But, when I look on Half.com, there are two books for IB Chemistry, a course companion made in 2010, and a study guide made in 2007. I was wondering which is the better one to get in order to study for the IB exam and assist with explaining concepts. I am not sure what the differences are between the course companion and the study guide, so I need to know which one is better to buy. If it helps, I'm taking SL Chemistry and the teacher is very good but there are a few topics where I need to refresh on from Chemistry I (Sophomore Year).
Last reply by kirann, -
Anyways.. What are your option material? I'm hopefully taking option B (Medicines and Drugs) and C (Human Biochemistry) alone. Anyone ever done both/one of them? What are yours and what do you think of them?!
Last reply by Award Winning Boss, -
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With the first exams for the new syllabus coming in May 2016, you could ask questions and post resources for the option topics here. For option B, I have a complete set of videos for SL and HL. I will be working on videos for option C next. Option B SL: http://www.msjchem.com/sl-option-b.html Option B HL: http://www.msjchem.com/hl-option-b.html Option C SL (almost finished SL, now working on HL) http://www.msjchem.com/sl-option-c.html Option C HL http://www.msjchem.com/hl-option-c.html
Last reply by IB`NOT`ez, -
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Hello, First year chemistry SL student here. I am struggling a lot with this subject, so I was wondering how all of you chem geniuses study? Any useful links would be much appreciated!
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Last reply by cricketcrazynerd, -
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Hello! We are supposed to come up with an experiment where we will be investigating a trend within a function group, preferably alcohols since we have got more than five different alcohols available. (Five is the magic number.) However, the only topics I can come up with are very complicated. For instance I had an idea of measuring the initial rate of reaction with a fixed acid by varying alcohols. and see of the intial rate of reaction would vary depending on the alcohols. This would not be an easy experiment since the product, an ester, would make its own layer, and it would therefore be hard to measure the pH of the remaining reactants accurately. So, do you have any …
Last reply by IB-Adam, -
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My teacher said our topics were supposed to be handed in late september, and I did so, but my idea was rejected, and done so again after I submitted a different idea. The IA 1st draft is due Nov.28 and I have an experiment now, but I still feel like I should ask for her approval but I feel like she'd be upset at me for holding it off so long and she won't approve my topic or do so as a last ditch effort to get me to pass something in. What should I do?
Last reply by kw0573, -
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Does anyone know a pH 10 buffer recipe? I showed my teacher one but we didn’t have10M ammonia so it didn’t work out. This is for an EDTA titration and I’m not sure if ammonia buffer is the only one I can use but I’m desperate for any recipes bc i’m conducting tomorrow!!
Last reply by Jaysun, -
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Hey all! Chemistry Exam is in less than 20 days this May. IB chemistry is amongst the subjects with the most diverse and heavy content, each interlocking with one another. However, my problem that my teacher pointed out is not being able to use my knowledge in various topics. For example if acids and bases tied up with redox reactions, I will get nervous and not being able to answer as well. How do you revise for IB Chemistry Exam? Do you have any advice for me?
Last reply by inriya, -
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I’m not sure what is meant by 30% ammonium hydroxide... is that concentration as a percent??? How do I prepare this using ammonium hydroxide?
Last reply by espress0s, -
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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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I haven't seen a thread about organic chemistry yet, so I'm starting one since I kind of need help. I would like to know certain things: 1) Does non-cyclical geometric isomerism occur only in alkenes? 2)It says in the study guide that some of the characteristics of geometric isomers are: - In the cis- isomer, H-bonds could form within the molecule it self. - in the trans- isomer, H-bond occurs between molecules. What I dont understand: wouldnt H-bonds form only when you have an OH group on the attached R-groups? So, how would that characteristic be valid for all cis and trans isomers? 2) I always don't quite understand elimination reactions. I know the mechanism an…
Last reply by Tilia, -
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I am self-studying option B, Human Biochemistry. I have found it ok so far as it overlaps a lot with HL Biology. However, I'm getting stuck in certain things on the syllabus that the books I have dont explain properly or unclear. So I have a few questions, that I think those of you who have done it with your teacher may be able to answer. B.6.2: Compare the structures of cholesterol and the sex hormones: It says stress on the steroid backbone and the difference in functional group. That's all the books mention as well. Seeing that its objective 3, I dont have enough details and I dont really see any other difference. B.7.2: Compare inorganic catalysts and biological …
Last reply by ozolins, -
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In dilute solutions, I compare each ion's reduction/oxidation potential with H+ and OH- respectively. However, for concentrated solutions, I keep reading that: anode: Although salt anion may have lower oxidation potential than OH-, because it is more concentrated, it is discharged. cathode: H+ is discharged. Why is it that at the anode you consider the concentration of the ions, but at the cathode, I've only ever heard H+ is discharged in these situations? ;o What would be an IB way of thinking through this? ;3
Last reply by Dasza, -
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Do we need to complete 2 Design Labs, 2 Data Collection Labs, and 2 Conclusion labs or 2 Design labs, 4 data collection labs, and 4 conclusion labs? Please help, thanks.
Last reply by anb2016, -
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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, -
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If the % efficiency of calorimeter is over 100%, does it mean that it is more efficient? Or is it not, because it got further away from the literature value. Thanks
Last reply by Keel, -
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Hehey! thanks for your help I am calculating the number of moles of ascorbic acid. mass = 0.250 +- 0.001 Mr = 176.12 n = mass/Mr = 0.00142 rounded up to 0.001 (to have the same amount of decimal places) (& +- 0.001, because it is dividing by a fixed value with no error). So the percentage uncertainty is 100% ????? hahaha hope not if so I am incredibly screwed
Last reply by Maha, -
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Hi! Are there any significant differences in 2007 or 2009 HL chem syllabi? My book is written in 2007 so I just want to make sure I haven't missed anything. By the way, all the best for tomorrow's exams! I'm actually kinda freaking about...I've been studying the whole time Chemistry and I'm still scared as hell of sitting the exam. I really hate myself for spending too much time on one question...I really hope I won't panick or anything ((
Last reply by Sandwich, -
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My chemistry is so demanding, but i'm no afraid of keep going. Anyways, someone can give a link or a doccument of the 2009 syllabus of chemistry SL, to know what and what not study. And some advice of what option to use, I thought about medicnes and drugs because I watch a lot of house, grey's anatomy, private practice, ER,Scrubs and Mental. And I've read a lot of medicine book thanks to that and I'm planning on becoming a doctor... can someone orient me please, or I just stick to enviromental ?
Last reply by sweetnsimple786, -
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Hey everyone! I was just wondering if anyone knows where to find the 2014 syllabus for chemistry HL. I know of ibchem.com, but I was wondering if anyone could point me in the direction of the actual syllabus? I just like to have an overview of everything but I can only find the 2009 one, which as far as I know has been changed! Unless, of course, the 2009 one is the most recent. In which case I apologise for this rather pointless question. Thanks in advance!
Last reply by Melissi, -
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What are all of the changes to the chem hl and sl syllabus for 2016? I was told that buffer calculations had been removed, and they even removed it from the textbook, but my teachers are saying that they will test us on it
Last reply by EmotionalEwok, -
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I did not fail chemistry as you would expect, quite the opposite. I am an IB diploma candidate and I am considering my hl to be chem, as for the only reason I would go to this extent of having took chemistry for so long. Is 3 consecutive years of chemistry appealing on transcripts? biology in freshmen year(9th grade), chemistry (regular, 10th), chem sl(11th), chem HL(upcoming senior, 12th)
Last reply by daxx, -
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I have a grade 4 in my chemistry internal assesment but my aim is to get a 6 in the final exam. I am just wonderin if that is possible. What should i do to be able to get a 6?
Last reply by Stereoisomer, -
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Hi I just got my IB results and I got a 7 in chem higher level, I was just wondering if anybody knows how many people achieve a 7?
Last reply by puka3300, -
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I was going through some past papers, and I got stuck on a question. Which list represents the halogens in increasing order of oxidizing strength (weakest oxidizing agent first)? A. Cl2 I2 Br2 B. I2 Br2 Cl2 C. I2 Cl2 Br2 D. Cl2 Br2 I2 I'm really confused about what this question is asking. It says 'increasing order of oxidising strength' but then 'weakest oxidising agent first'! From what I know, these two contradict each other ,no? what oxidises loses electrons, and what reduces (oxidising agent) gains electrons. So does this question want me to list halogens that are least likely to oxidise -> most likely? or most likely (weak oxidising agent) -> least …
Last reply by Ezeh, -
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Hi guys! I writing a report for my internal assessment, in which I investigated the effect of the concentration of the electrolyte at the anode of a voltaic cell on the total potential difference across the cell, and I have stumped upon a problem with formulating the aim. The thing is, that there is an equation for the relationship which I am investigating (the Nernst equation) and I do not know whether my aim should be to just "investigate the relationship" or to "investigate the relationship and see, whether it follows the Nernst equation"? This is important because there are several sections which I will have to write differently depending on the aim.
Last reply by Drake Glau, -
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hey everyone, i have this lab to do and the problem is that when finding the uncertainty for concentration, i only have the uncertainty available for volume, not for moles since C=n/V. So, my question is: does my uncertainty for concentration equal the uncertainty of the volume or do i have to do something else??? thanks for any help ....
Last reply by IBdoc, -
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Hey guys, I have a quite stupid question. I can ask it when the school begins next year but I can't wait for the solution. It will be awesome if you could explain the process to me step-by-step. Thanks here is the question A student wished to determine the percentage by mass of calcium carbonate in an eggshell. She reacted 3.953g of the eggshell with 50cm3 of 1.00moldm-3 hydrochloric acid. After all the shell had reacted, the resulting solution was placed in a volumetric flask and the volume made up to 100cm3. 10.0 cm3 of this soluiton reacted exactly with 12.65cm3 of 0.100moldm-3 sodium hydroxide solution, NaOH(aq). Calculate the percentage by mass of calcium carbon…
Last reply by Baller97, -
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what is the pressure , in pa, in a 100cm3 container containing 1.8g of steam at a temperature of 727 C?(R=8.31 JKmol) The key is (1.8)(8.31)(1000)/(18 * 10^-4) but I don'e understand that where is temperature..the formula is PV=nRT right? Also what is 1000 standard for and also 10 to the power of -4?
Last reply by kw0573, -
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Hi! So I'm just doing a lab write up at the moment and I'm up to an absolute uncertainty calculation... Absolute uncertainty calculation (3.13/100) x 24.406745 = 0.76393... Am I supposed to round this to 1 and then also round my reading of 24.406745 to 3 sf? So it would be.... 24.4 ± 1 kJmol-1 ?? Thanks in advance!!
Last reply by dessskris, -
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So, I have somewhat an idea of what id like to do involving my chemistry IA but I'm in need of an opinion and or suggestions. My idea is an experiment testing the affects of Carbonic acid (due to ocean acidification) on shelled organisms and others that use calcium carbonate. Perhaps testing at which concentration it is harmful? I dont have a specific or elaborate idea and am struggling to think of one all i know is that this topic is important to me and the world itself. All suggestions welcome please!
Last reply by Siddhakshi, -
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Please help me with this question: Determine the pH of a solution formed from adding 50.0cm3 of 1.00moldm-3 ethanoic acid, CH3COOH(aq), to 50.0 cm3 of 0.600moldm-3 sodium hydroxide, NaOH (aq) mark scheme: (initial)[CH3COOH] = 0.500 mol dm–3 and) eqm [CH3COOH] = 0.200 mol dm–3; (initial)[CH3COO–] = 0.300 mol dm–3 and) eqm [CH3COO–] = 0.300 mol dm–3; Allow 0.02 moles and 0.03 moles instead of 0.200 and 0.300 mol dm–3. [H+] = Ka = 1.16 × 10–5 mol dm–3 / pH = pKa + log; pH = 4.94; Award [3 max] for correct final answer if no working shown. I'm not sure where that "(initial)[CH3COOH] = 0.500 mol dm–3 and) eqm [CH3COOH] = 0.200 mol d…
Last reply by kw0573, -
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Please help me with this question: Question: 25.0 cm3 of 1.00 × 10–2 mol dm–3 hydrochloric acid solution is added to 50.0 cm3 of 1.00 × 10–2 mol dm–3 aqueous ammonia solution. Calculate the concentrations of both ammonia and ammonium ions in the resulting solution and hence determine the pH of the solution. Mark scheme: initial amount of HCl = × 1.00 × 10–2 = 2.50 × 10–4 mol and initial amount of NH3 = × 1.00 × 10–2 = 5.00 × 10–4 mol; final amount of NH4+ and NH3 both = 2.50 × 10–4 mol; final [NH4+] and [NH3] both = = 3.33 × 10–3 mol dm–3; [OH–] = Kb × = Kb = 10–4.75 /1.78 × 10–5; pOH = 4.75 hence pH = 9.25; I don't quite understand …
Last reply by Msj Chem, -
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Hi, I conducted a typical titration lab where I reacted HCl with NaOH. I now want to find the Ka value for HCl. The molarity of the HCl was .1 mol dm-3 and its initial pH was 2.80. Using log, I converted 2.80 to H+ concentration. I know [H+] = [Cl-], yet somehow, I am getting a really low value for ka, which shouldn't be. Any suggestions? Thanks
Last reply by ILM, -
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This is for a planning lab investigating the effect of acid rain on building materials. I'm planning to use the type of material as my independent variable. I know that limestone/sandstone/marble are significantly affected by acid rain, but are there any types of building materials that AREN'T really affected by acid rain? I can't think of any since I know acid rain corrodes metals (iron/copper) too...
Last reply by Sauliooz, -
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Hi, I'm stuck on what idea to do for my chemistry IA, so I'm wondering whether you guys could help . I'm thinking of doing an acid-base/equilibrium IA, but I have no idea where I want to go from there. This can change though if there are any better ideas!
Last reply by Amberrose248, -
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Does anyone know a good website that has questions relating to the acid-base unit? I want to have some extra practice before my test. Please don't give me the link to the syllabus.
Last reply by Stereoisomer, -
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Hi what will happen in this reaction 2 NaOH + H2SO4 → Na2SO4 + 2 H2O when I increase the concentration of one of the reactants. They form salt and water will a pH of 7. But if I increase the concentration of one of the reactants? will it effect the pH?
Last reply by Keel, -
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The answer is B; Can you fully explain the question and how it is solved, thanks!
Last reply by kw0573, -
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So I recently came across a question that I just can't figure out (it might be really simple but I seriously need help with this one). So here it is: What is the concentration of OH– ions (in mol dm–3) in an aqueous solution in which [H+] = 2.0×10^–3 mol dm–3? (Kw = 1.0×10^–14 mol2 dm–6) A. 2.0×10^–3 B. 4.0×10^–6 C. 5.0×10^–12 D. 2.0×10^–17 If you could just work through the steps to give you the answer (which by the way is C according to the markscheme) that would be great. Please help, it's killing me...
Last reply by Msj Chem, -
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May anyone please answer these questions in detail? thank you! The answers are A and D, respectively.
Last reply by Msj Chem, -
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pKw for water at 10^oC = 14.54. What is the pH of pure water at this temperature? a) 6.73 b) 7.00 c) 7.27 d) 7.54 The answer is c, I fully understand how to get to this answer, however I don't know how to do it without a calculator due to the difficulty of the arithmetic involved. Which is correct for a weak acid, HA, with concentration 0.01 mol dm^-3 at 298K? a) [H^+] < 1x10^-2 b) pH < 2 c) [OH^-] < 1x10^-12 d) pOH > 12 The answer is A, why is that? isn't the concentration of H^+ exactly 0.01 mol dm^-3 as stated in the question? why is it less. Another question I have is whether the mixing of differe…
Last reply by kw0573, -
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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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In a practice question I was doing, it says that 10 cm^3 of 0.01 mol dm^3 of HCL is diluted with 90 cm^3 water and the questions ask to calculate the ph. So if I am correct, the starting PH is 2, due to 0.01 mol being equal to 10^-2. 2nd, with the 10 cm^3 of acid being diluted with 90 cm^3 of water, then would that cause the resulting ph to be a value of 3 as the water dilution makes the acid less acidic?
Last reply by Msj Chem, -
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Hi, I am currently studying chemistry have 2 questions: 1. It says in my text book that ''acids react to form bases and vice versa''. But how is that always true? For example, a base is not formed when an acid reacts with a metal to produce a salt and hydrogen gas, right? 2. If I have understood it correctly, Kw=H+*OH- and in a neutral solution (ex. pure water), H+ = OH- and hence sqrt(Kw)=H+. Does this also mean that sqrt(Kw)=OH-?
Last reply by inshm2016,
