Chemistry
For Chemistry Discussions
1,617 topics in this forum
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- 1 reply
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Hey Guys, Sorry if my last topic was against rules I didn't realise they cost for individuals to buy. Anyway I have had a search on the ibo store but cannot find any of the 2012 may papers. Does that mean they are not avaliable or am I looking in the wrong place. Please help.
Last reply by Kayla Jackson, -
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Hey Guys, I was wondering if there is some way I can get my hands on May 2012 Chemistry HL paper 1, 2 or 3. I would really like to use them to practice because I can't find them of question bank and my school will not pay for them till after mock exams. Thanks heaps.
Last reply by The Economist, -
Research question for EE?
by Guest TushieHushie- 1 reply
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Hey guys! For my extended essay I want to find out whether sugar free juices really are sugar free. For that, I'm breaking down the sucrose (if there are any) in the juice and reacting the glucose with a reagent in order to quantify it. And now I need help with my research question. I have one: "How does the concentration for free glucose and sucrose vary in apple juices of different types?" But my teacher says I need to rewrite it so it sounds more chemistry related and maybe even more sophisticated. And in different types, I meant the concentrated ones, single strength ones, etc. But I don't know how I should improve it. Please help me, thank you
Last reply by Emmi, -
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Take an oxygen atom. Adding 2 extra electrons will absorb some energy to put them into orbit. Now that it has a noble gas configuration, if I try to force 2 more electrons into its orbit, what happens? I know that this is very improbably, but I'd like to know what exactly happens.
Last reply by Drake Glau, -
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Hey guys, i really need help on this question: How can i close off a syringe so that i can measure the variation of the volume of the gas inside while changing the temperature? I tried melting the tip, but it doesn't work. I would gladly appreciate any suggestions. Thank you!
Last reply by eelnedross, -
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Hello ^^ I am currently working on my IA, and I have been really confused by this problem: If a value is multiplied by a constant, does the same occur to its uncertainty? For example, (45.0 +/- 0.1) cm but if the value of 45 is doubled,, would it be (90.0 +/- 0.1) cm or (90.0 +/- 0.2) cm ??? I think I have come across this problem before, but I forgot what I did then. I would be grateful if you could help me with this problem. : ) Thanks!
Last reply by CkyBlue, -
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How does the chemistry options work ??? and in paper three when they give you questions about all the options, do you choose any two to answer or what ???
Last reply by CkyBlue, -
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I have been tutoring Chemistry for over 2 years now and one of the topics students continually struggle with is Bonding, especially with regards to bond angles and VSEPR Theory. The key points to remember from VSEPR Theory are: - Electrons repel each other and thus spread out to minimise repulsion - Lone pairs further compress the bonding angle (I use 2 degrees as a rule of thumb) Throughout this explanation, I will be referring to negative charge centres, defined as: - A Single, Double or Triple Bond (Counts as one negative charge centre) - A non-bonding pair HL students can use this definition: - sigma bond - non-bonding pair The hard part is working out how many …
Last reply by SerUmbras, -
Lab Report DCP- Graphing Data
by Guest Humaira- 5 replies
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what data do you plot on the graph? is it for example averages from the raw data? also, the raw data is never plotted right? the IA I'm doing is the length of time it takes for HCl and Mg to react completely with different concentrations of HCl in a 10 ml solution( ranges from 10 ml of just HCl to 5 ml of HCl and 5 ml of distilled water) . as well as the volume of gas produced from downward displacement. Im confused about what to plot on the graph. as well for my design IA, our teacher gave us the topic of: Investigate one water contaminant ive made two questions, but i dont know of either one is even good for this? here they are: how does the concentration of boron ions …
Last reply by Drake Glau, -
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Hey guys! Do you think it is a good idea to write about the acidity in fruits for my extended essay? I was thinking like: How does the pH level change depending on the ripening of apples compared to bananas? I am not very good at formulating research questions (as you can see) lol.. but is the idea okay? Thanks in advance!
Last reply by Kai Braunbeck, -
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My lab portfolio is being sent to IB since I'm the only HL level in my class. Does the whole thing get sent to IB or just the two that my teacher scores? What happens if I do not turn in all the labs that we have done in my class? I've turn in about 90% of the labs that we did
Last reply by Drake Glau, -
- 4 replies
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Hi all, Just finished mock week and fair to say the results aren't going to plan. I studied like mad for chemistry by reading my text book, copying, reading and none went in.... a level 3 is not where I want to be for very long. Does anybody have any tips/ ways they revised/ remembered? However 'quirky' or boring i'm willing to give them a go! I will be getting the Pearson book as soon as I can Cheers H
Last reply by Hens48, -
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My class will NOT stop arguing about the options we get to choose. We have a split between Modern Analytical Chemistry and Medecine and Drugs. We have half a class of physics students (half unwilling). So what i want to know is what options people have enjoyed the most and found easiest. Muchos gracias
Last reply by miss mel, -
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I accidentally put a higher amount of significant figures for my percentage error, (stupid error, I know) but my teacher took points out from DCP because of that. I didn't know calculating the percentage error of an experiment was part of the DCP, isn't it part of the conclusion where you evaluate how accurate/inaccurate your experiment is? When I asked my teacher about it, she said it was, but my physics teacher said the opposite, so I just wanted to know how you guys have been taught. Thanks for your help:)
Last reply by Drake Glau, -
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Hi guys, I'm sorry that the title is a little vague, but I really couldn't come up with anything more clever. So, this is the case: For my lab report I needed to calculate the the acid dissociation constant of an unknown weak monoprotic acid. The values which I could measure were mass (the acid was pure), volume and ph (plus the molar mass of the acid given by the teacher). So to simplify the process, I derived a fancy formula that allows me to do it in one step, instead of going through like five of them (don't worry, I've checked the correctness a million times, so there are no errors in this part). But then I had to calculate the uncertainty for my acid dissociation c…
Last reply by norsul, -
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so I'm currently a sophomore, I'll start IB next year, and I plan on taking IB chemistry as one of my HLs. I've gotten high 90s (96-100+) in both pre-IB biology and chemistry but I just prefer chemistry because there isn't as much memorization as there is in biology and I actually think chemistry is fun and biology really boring! thing is though I've heard HL chemistry is a killer but teachers at my school have not really given us any warning...am I setting myself up for disaster??? help! if it makes a difference, right now I kind of want to be a pharmacist.
Last reply by Danbo, -
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Hey, i have a quick test for the class of 2012 and anybody else who wants to give it a shot..ready?? ok.. 1)how do molecules in a gas exchange energy? 2) what effect, if any, does the exchange have on the maxwell-boltzman distribution curve? 3) give two changes that would cause the number of molecules with energy greater than activation energy to increase.. good luck!! they are very simple though... Click the spoiler for the answers.
Last reply by Drake Glau, -
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So I am going to start my chemistry IA soon and I was hoping for suggestions. Our IA deals w/ chem kinetics and I pretty sure that I'm just going to do something with temperature change. I was planning on changing the temperatures, finding the orders of the reactions, and then plotting an arrhenioius plot and finding the activation energy. I'm wondering if this seems like a good plan? And what solutions do you think would be the simplest to use?
Last reply by greeneyeliner, -
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From what you guys have been faced with and seen, are organic chemistry questions likely to show up on Section A of Paper 2 of the IB Chemistry SL exam?
Last reply by Smile44, -
- 1 reply
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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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Do you have to learn the chemical tests by heart for IB chemistry?? And if you do, then how did you learn them??
Last reply by Michel Tabari, -
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So i had begun studying my options for the exam and randomly chose options F. This sections was Food chemistry on my reference book. I finished my studying and began looking for some past exam to work on, but to my confusion i saw "Fuel and Energy" on options F. I checked other years and say that options F changed between the Food Chem and "Fuel and Energy". How does this work? Does options F change each year?
Last reply by The Economist, -
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Hey, I've been struggling with this, *The table of values is in the attached file* First of all whats the order of the reaction with respect to iodine? its kind of confusing since when the concentration is halved the rate increases by 4 times! second, Suggest a reaction mechanism for the same reaction reaction: CH3COCH3+I2=H++I- in the presence of sulfuric acid as a catalyst ( the H+ ions from the acid catalyze the reaction) any ideas? Thanks Doc2.docx
Last reply by Drake Glau, -
- 2 replies
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Hey guys! Taking chemistry HL and I was wondering whether it is required to study the "Extension" parts of the syllabus as well? We've had debate about this in the class and the teacher doesnt have the answer. (e.g studying "the chemistry of individual transition metal elements" in the periodicity chapter). only a week left til the exam!
Last reply by Emmi, -
Theoretical Yield
by Guest Humaira- 4 replies
- 1.9k views
when calculating the percentage yield for an experiment, is the same theoretical yield used for all of the trials even when there is different amounts of one reactant used? for example for my practise IA, we are finding the percentage yield of CO2 ,30 seconds after baking soda and vinegar have reacted. we used different amounts of vinegar in our experiment we used 3.6g, 7.2g and 14.4g for different trials and 0.5g of baking soda for all of the trial when i did the calculations to find the mass of vinegar needed i got 3.6 g as the theoretical yield for vinegar, does this mean that the percentage yield that we calculate use the same theoretical yield of 3.6g for all of the …
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Attached is the image of the desired structure, my question is based on what is pictured as (CH3)2HC- I represented this group as C3H7 which does seem like the logical equivalent, but just being safe here. Am I right?
Last reply by Drake Glau, -
Quantitative Data Tables
by Guest Humaira- 2 replies
- 1.4k views
What do quantitative data tables include? do we have to have one table that has the mass of the reactants and another table for the mass of the products? for example, the practise IA my teacher gave us is on the percentage yield of CO2 from the reaction of vinegar and baking soda. also what is the difference between quanititative data tables and qualitative data tables?
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Hello! This is one of the few threads I've ever started, so hope no problems! Anyway, I have environmental chemistry and medicines and drugs as two of my options. So given that there's only 4 or 5 days before the exams can you suggest some great notes on the internet? the files section here (ill prolly upgrade) but these notes shouldn't be just general running notes taken in class rather stuff that teaches you how to score in the exam, key terms, concepts , repeated questions? I hope you can help and thank you in advance!
Last reply by DropBoite, -
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I'm currently working on an organic chemistry assignment where we are told to explore all 12 functional groups of organic compounds. I'm stuck as to how to give the general molecular formula for these 12 (alkane, alkene, alkyne, alcohol, ether etc), so could anybody help me out? Any help is appreciated. This is what I have so far and I'm sure there are some mistakes. n = subscript for the number of atoms. Alkane - C(n)H(2n+2) Alkene - C(n)H(2n) Alkyne - C(n)H(2n-2) Alcohol - C(n)H(2n-2)OH Ether - C(n)H(2n+2)O Aldehyde - C(n)H(2n+1)COH Ketone - C(n)H(2n)O <---- should the O be somewhere in the middle of the formula since it is a ketone? Carboxylic acid - C(n)H(…
Last reply by Drake Glau, -
- 2 replies
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The other day we were given our first IA for chem and our teacher hasn't given us a layout or anything like that. I'm a bit stuck because I have done all the information but I don't know if my layout is right... Is there a certain way that we are supposed to lay it out, or do we just throw all the information together? Its due this week and I am beginning to get worried. Thanks.
Last reply by Tony Stark, -
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Attached is a screen shot from a test markscheme I obtained from school. It asks us to quantify the bond angle which is fine, but I cannot understand the language used to refer to the bond being spoken of. The terms I don't understand are: Inplane Cl-I-out-of-plane Cl |Equatorial F-S-Equatorial F You can understand why this is confusing as the image shows all the bonds as being equatorial (googled it ) I understand that term now, but I still don't get the first sentence and which atoms are being referred to. Thanks All!
Last reply by Peanut Butter Jelly, -
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How do you find: 1: Total heat released by reaction 2: Heat released per mole of Mg Someone please help me out, I have no idea how to do this.
Last reply by Hailzter, -
Chemistry HL exam help
by Guest Jar Jar D'oh!- 3 replies
- 1.5k views
Yeah, so I'm trying hard to be calm, because my exams are tomorrow and it's obviously my fault that I'm in this position, so patronizing lecturers can save themselves the effort, I really need the most effective ways to crack past papers in Chem HL. my weakest chapters are: Kinetics, the Energetics, and who doesn't find Organic tough? Could you point me to papers patterns or anything useful, I really need help.
Last reply by cguerin, -
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Hello people, Chemistry exams are comming up soon so I came up with an idea for us to share what WE think will come up this year on the paper, as You know the IB examiners do not spend much time creating questions and mainly end on previous ones. Haha. WHAT DO YOU THINK WILL BE ON THE TEST THIS YEAR ?? PS. I know this may be lame but it helps to reduce. Believe me!!!
Last reply by Emmi, -
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Hey, So I need to write 1 more design lab.. I was thinking a photosynthesis lab could be pretty simple. I could just measure what effect light intensity has on the oxygen produced or something like that. Is this okay for a chemistry lab, or can it only be done for biology? Also, if anyone has any ideas for design topics, your help would be greatly appreciated.
Last reply by LMaxwell, -
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Hey! So, our class does not have a chemistry teacher at the moment and our teacher has already taught us Drugs and Medicine and taught, very poorly, Human Biochemistry. I take physics, and not biology, so I find the option very difficult as it required a lot of memorization! I looked at the Environmental option and although requires a fair deal of memorization, seems simpler. I will need to learn a whole option by myself in a few weeks.. so which one do you think is easier to learn? Thanks!
Last reply by omri, -
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I'm not sure whether there's a thread on this yet; sorry if there's already a similar thread on here. A while ago I stumbled upon this user on YouTube called richthornley, and I believe he's an IB Chemistry teacher. He has a lot of incredibly useful and entertaining videos on Chemistry syllabus statements, and he adds new videos every now and then. Here are some of his videos. He has many more I play video games so I find his videos especially interesting - he teaches using video games like Team Fortress 2 and Garry's Mod! Feel free to share other Chemistry revision videos
Last reply by Samuel Golobov, -
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I have 50 cm3 of sodium thiosulfate at 0.2 mol/dm3. If i used 30 cm3 of it and added 20 cm3 of water, whats the new concentration? Thanks for your time
Last reply by LikeA'13OSS, -
- 1 reply
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okay
Last reply by The Economist, -
- 1 reply
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Hello!! I am currently a senior and take my IB exams in less than a month. I'm taking Chem HL, and all of my friends who have been reviewing have told me that this study guide is very concise but also very detailed. I am good at chem (am hoping for a 7!!), so I didn't buy this study guide before. However, I would now like to acquire one. Does anyone know where I can either get a free pdf version (or at least cheaper than on Amazon)? I will only use it for 2 weeks or so, so I don't feel like I should spend $40 on this when I'll be done with my IBs in just a few weeks. Thank you, Max
Last reply by IVIax94, -
Chemistry Design Lab Length?
by Guest Humaira- 4 replies
- 1.3k views
this is my first practise IA which is not marked. the question my teacher gave us is : What kind of experiment could be performed to test the law of conservation of mass? ok ive figured out what i will be doing which is vinegar and baking soda and the variable that will be changed is the temperature of the vinegar. i was wondering how long should this design lab be? 1-2 pages? how much should i write for the variable portion? also what is exactly is the data collecting portion? is it the quantity of each material, the temperature, the mass etc?
Last reply by Tony Stark, -
- 3 replies
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Well, do they? You're help is appreciated(:
Last reply by CkyBlue, -
Chemistry lab uncertainty help?
by Guest SlimShadyFan- 3 replies
- 903 views
I'm doing an experiment and have these values: Initial temperature: 21.0°C ± 0.5°C Final temperature: 63.0°C ± 0.5°C (1st trial) 60.0°C ± 0.5°C (2nd trial) So the average change in temperature is 40.5°C. Now I need help with my uncertainties. I'm not sure how to find it out. Do I just add all the uncertainties and get ± 2? Please help me
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Hello all! So toward the end of the chapter energetics, we have a calculation for Lattice enthalpy (apologiess!!) where it is calculated for NaCl, I'm sure this is a commonly used example in most text books, I hope you can relate . my question is how do I draw the energy cycle/ born-haber cycle as the IB chem guide presents a different way of drawing it, distinctly so and the Pearson HL textbook shows the diagram on an enthalpy chart! What do I do?
Last reply by Sammie Backman, -
The enthalpy of combustion of alcohols, help with experiment?
by Guest Tuvshee Otgonbayar- 10 replies
- 6.7k views
In chemistry we're supposed to find the enthalpy of combustion of propanol. In order to do that, we burned the propanol and heated up the water with it. Now we have: time: 300s mass of water: 50.0g change in temperature of water: 24.2K change in mass of propanol: -1.5g specific heat capacity of water: 4.18J/g/K molar mass of propanol: 60.11g/mol So change in enthalpy of water is = cmΔT = 5057.8J This is also change in enthalpy of 1.5g of propanol We want the change of 1 mole so we calculate: (5057.8 x -1.5)/60.11 = 202683J = 202.68kJ However, the enthalpy of combustion of 1 mole of propanol is 2026.8kJ. It seems that I'm off by one decimal place, but…
Last reply by Drake Glau, -
- 6 replies
- 1.7k views
I'm just sitting on a final lap report (we call them pracs for whatever reason) and am wondering as what it would count: It started as a pure design prac, I then adjusted it to perform an actual experiement. Specifically I want to know whether it still counts as 2 pracs or as one? (Apparently a Design and a Performance/manipulative skills prac have to be sent to the IBO). Also, error calculations: rates of reaction at different temperatures (carbonate and acid -> co2), should the uncertainties of the scales and the temperature probe be used in the final calculation (after average is calculated) or at some other point? Kthx.
Last reply by Akayuki + Lucifel, -
Aspect Three of a Design Lab
by Guest Humaira- 3 replies
- 726 views
Is aspect three of the design lab the procedure?
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Hello everyone, I am doing two DCP labs, both of which the graph produced are in the form of bar graph.s Hence, there are no trendlines or equations of the slope. So, does this account for an accepted DCP format ? Thanks.
Last reply by Hyunqul, -
- 12 replies
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Hi! Apologies in advance if this has been asked already. But what do you think is the best way to study for Chem besides doing practice papers and obviously going through your notes? Is going through the syllabus an efficient way to study? Thanks!
Last reply by Artoth, -
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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,
