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kw0573 last won the day on January 15

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About kw0573

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  1. You can use mol ratio if you assume that NaOH only deprotonates ethanoic acid and HCl. But you can also use the pKa of ethanol to calculate the equilibrium constant between ethanol and NaOH so see how accurate that assumption is. For example if you were to discover that the ethanol - NaOH equilibrium is 3, then that would mean the assumption is invalid and the acid titrated minus HCl added accounts for both ethanoic acid, as well as some part of ethanol. If you look up the solubility of ethyl ethanoate in water, you would see that it is not very soluble. Clearly in an equilibrium, you would expect ethyl ethanoate to be present in a own layer.
  2. Vitamin C titration is a common idea. In addition to the usual titration where one should explain why does the titration work, you would also have to relate cooking time to possibly temperature of the vegetable, to explain why would vitamin C concentration decrease (decomposed? evaporated? loss in water?) and most importantly, work with concentrations on a level allowed by your apparatus (in a vitamin C titration of a citrus fruit, you would not worry about too little ascorbic acid, but there is much less of which in many vegetables). I think it's a creative idea in the right direction, but I think it may be too ambitious in the current form of the question.
  3. First you should understand that sodium, on a nutrition label, is not the sodium element, but the sodium ion. Sodium element and water react quite harshly. Therefore there are counterions, or anions, also present in the solution, and you should determine if these counter-ions affect the conductivity (which I do not know the answer to). Moreover, I am not convinced that conductance, a physical property of a solution, alone is enough for a chemistry IA. All it seems, and forgive me if I misunderstood, is that you want to take salts, dissolve in water; I just don't think that's enough. Dissolving salts in water is not electrolysis. The idea of aiming to replicating some phenomenon (which is different from replicating some procedure) is ok, you don't technically need variables. However, you should review your chemistry knowledge and pick a topic of which you know very well conceptually.
  4. Though you have correctly identified that HCl is a catalysis, you should read on reactivity of carbonyl/carboxyl compounds to determine whether the introduction of -OH may have impacted the reaction (during the time you performed the titration). Consider the two products, ethanoic acid and ethanol. NaOH deprotonates ethanoic acid, I agree, but you should also calculate if it can significantly deprotonate ethanol? What would be the equilibrium constant be between ethanol and NaOH? My final remark is regarding your observations of the final solution. Is there a single layer of liquid or multiple layers? In organic chemistry there is the "liquid-liquid extraction" technique, commonly known as "work-up", where you can separate different layers of liquids, which may be useful for you if you did observe 2 layers.
  5. I want to clarify that I will try to ask questions to help you identify potential flaws (that I probably am not aware of) yourself. Is the equilibrium constant correctly calculated, accounting for all species in the equilibrium? If the equilibrium is between water and ethyl acetate, why is the amount of acid of interest? Would -OH in any way, react with ethyl acetate, or in some other means alter the equilibrium?
  6. No one person can provide a summary for all Canadian schools. If we have confirmed that 1450/1600 is a fairly competitive score and that 24/42 is low, possibly below many minimum IB requirements, you can gather more information by looking through the USA & Canada sub-forum for a collection of many many users' input on their impression of the schools as well as admission requirements. Your friend should first identify specific programs (and/or majors) of interest, and the desired semester of entry. A lot of schools allow an application to be made by end of January / early February, allowing documentation to be completed at a late date, possibly March. For example Ontario (a province in Canada) universities can be applied from, from which I learned, by random, that McMasters Arts and Science program requires 3 in IB English and 3 in Math SL/HL. Your friend can go through the site, and similar sites, to learn about admission minimums of schools. IELTS or TOEFL were mentioned; they are not required for someone from a English-speaking school in a English-speaking country, whom of course is expected to ace either test. Considering that many Canadian universities are closing admissions within next two weeks, and that you have not made clear what major your friend is interested in, he should immediately narrow search with the major in mind and apply to 2 or 3 schools without a minimum total IB requirement. I do not believe that your friend has time to prepare for and take any additional SAT tests in time for September 2017 admissions in Canada. The fall back plan is to try his best (with or without retakes) to apply later with more carefully prepared applications not made in rush.
  7. How are you sure that equilibrium has been reached and maintained? What exactly are your measuring in the titration?
  8. Who's to say practice doesn't work with English? I am sure that if you write a commentary/essay a week then you will see your writing improve. Saying you are a "science student" is just giving yourself excuses. It's not possible to redo the IOP, unless your teacher gives everyone the chance to do so. Of course with only 15% of your final grade known, it is still mathematically very possible to score a 7.
  9. Recall transformations of a function and that g(x) = e^x has a horizontal assymptote at y = 0. f(x) is g(x) vertically stretched by a factor of 10, horizontally stretched by a factor of 1/0.201, reflected across the y-axis, then translated 3 units up. As a result, the new horizontal asymptote is at y = 3, which is only affected by any vertical translation. In general, the horizontal asymptote(s) is/are y = limit f(x) as x--> +/- infinity. Since the limit in this case towards negative infinity does not exist, the only horizontal asymptote is the y = lim f(x) as x--> + inf = 3. Both ways are valid and both need some visualization of the function in question.
  10. b) Sin rule relates two angles with two sides. To limit to one unknown in the equation, we use the angle BAC 30° = angle A. a / sinA = b / sin B. BC / sin (30°) = AC / sin x. AC = (4) sin x / (1/2) = 8 sin x. c)i) Set the two equations equal to each other: 8 sin x = sqrt (41 - 40 cos x) square both sides 64 sin²x = 41 - 40 cos x The straight forward method is to change 64 (sin²x) to 64 (1 - cos²x) using the pythagorean identity 64 - 64 cos² x = 41 - 40 cos x 64 cos²x - 40 cos x - 23 = 0 Solve the quadratic for cos x. Because B is greater than 90° and less than 180°, cos x is between 0 and -1. x≈-0.36354 arccos give angle in 0° to 180°, assure calculator is in degrees, arccos (-0.36354) = 111.32 °
  11. If the class' IA average is more than 15% different from pre-moderation average, eg pre-mod average is 15/20, after mod it becomes 12/20 (75%to 60%) then the coordinator can request that the class be remoderated. Otherwise, IAs cannot be resubmitted or regraded. You can choose to have a subject (non IA) re-marked, or re-sit in the May 2017 exam, the latter you should decide by Jan 29. Re-sit fees can be refunded upon a changed final grade upon re-mark.
  12. It seems you want to do something calculus-related. You are not obliged to have data in the exploration but you can. Math IA is about demonstrating your math problem solving and/or analytical skills, as opposed to replicate a textbook solution. All three are good but the basketball is the weakest: it is a physics problem and is not very math-heavy. I like the coffee one the best because the data is easy to collect (and there is a model on it). You should still keep looking for more ideas. If you do end up doing regression, remember IB is not assessing how well you can punch in numbers into a formula but rather your justification of any formulae used and your thought process.
  13. A diploma is not awarded if an IA is not submitted. If a complete IA is submitted but just gets low marks, then it would contribute to the final grade. There is only subject pass/fail or diploma vs no diploma. No pass/fail is associated with any single IA or paper.
  14. What you can do is for each topic you come up with, make a 1-page summary of in detail of 1) how to approach the question 2) aspects of math involved (eg modelling, calculus, conditional probability, etc) 3) evaluating your math skills and devise a plan to score the highest mark. You should read appropriate sections in the Math SL guide (see below) for IA requirements. Other types of Math IA can involve different branches of math covered little in syllabus (eg matrices, prime numbers), math in other discipline (eg math in economics/physics/biology), or relationships between math concepts (such as geometry and series, trignometry and algebra). You current options are equally valid. As with all IAs, you want to explore multiple ideas during brainstorming and make detailed plans. It's often a good idea to write a practice or mini one (just 3-4 pages) to get the feel. In all written IAs, your teacher can proofread your work to be submitted only once, so it's best to get all the advice and tips from practice IAs.
  15. I think that, if well presented, the level of infinite series and convergence/divergence is more than enough. Math level is not the only criterion that examiners are looking for, so be sure to revise for other points as well, including organization, creative/original thinking, and presentation.