CHEMISTRY COMMUNITY

Vivian Chang 3L

I think Dr. Lavelle did mention at some point that it was 10 -3 but I think he also mentioned that you should actually use 10 -4 as an indicator just to be on the safe side. Even when it's 10 -4 , I still check with the 5% rule just to make sure it works because I think one time I did a problem and ...

Vivian Chang 3L

I've definitely been feeling the burnout :( What I've been doing is switching up my studying space. When I start to get distracted or bored, I'll move into a different room to do my work for 1-2 hours before moving back. Another thing that really helps me is planning out a schedule so I know what ex...

Vivian Chang 3L

I really liked coordination compounds from 14A and chemical equilibrium from 14B! I actually enjoyed pretty much all of the chem topics in both 14A and 14B except thermodynamics and thermochemistry lol

Vivian Chang 3L

I'm a first year, and I'm most looking forward to some of the increased independence I'll get! I'm also really looking forward to trying out all of the yummy foods and meeting new people :D

Vivian Chang 3L

I think it wouldn't be advisable to do all of your studying in one day :( If you can, like someone above suggested, I would really try to squeeze in 20-30 minutes of studying each day leading up to the final. I think that would help lower your stress tremendously and help you retain info better too....

Vivian Chang 3L

I literally can't decide because I feel like I change my favorite food once every 3 weeks or so lol but!! some of favorite foods are probably pad thai, sushi, mango, boba, and cookie dough or mint chocolate chip ice cream!! I have my phases but PAD THAI always hits home without fail. I've also had t...

Vivian Chang 3L

Here are some things I keep in mind when writing cell diagrams: - Always make sure you put the oxidation half-reaction on the left, reduction half-reaction on the right (to remember this, you can think about how "reduction" and "right" both start with the letter r, so the r's go ...

Vivian Chang 3L

I personally don't really understand the method that I think most people are using, so here's how I do it (the method I was taught in high school!): - Follow all the same steps to balance a redox reaction in an acidic solution - At this point, you'll end up with H+ on one side of the equation, but i...

Vivian Chang 3L

I'm definitely planning to relax as much as possible!! I'm going to binge watch all the shows I've been putting off and sleep in a bunch without feeling guilty. I've also been stressing out about whether or not I want to change majors, so the plan is to figure all of that out during Spring Break too...

Vivian Chang 3L

Hi! For the Chem 14A final, I studied primarily using textbook problems and lecture notes, and I was good to go. For the Chem 14B final, I'm going to use the same studying materials. I usually learn the most going through textbook problems because there are a lot of small details not usually covered...

Vivian Chang 3L

Hi! This is how I was taught balancing redox reactions for acidic and basic solutions: For acidic solutions: - Write out the oxidation and reduction half reactions - Balance all elements other than O and H - Balance O using H 2 O - Balance H using H + - Balance electrons and make sure charges on bot...

Vivian Chang 3L

I'm not sure if this is offered next quarter, but I highly recommend Ethnomusicology M50A or M50B with Professor De Castro! I took Ethnmus M50A with him fall quarter and I really enjoyed the class. You don't need any prior musical background knowledge and the quizzes/tests are all super straightforw...

Vivian Chang 3L

Hi! Like everyone else said, you could remember it as OIL RIG (Oxidation Is Losing & Reduction Is Gaining) or (how I learned it) LEO the lion goes GER (Losing Electrons is Oxidation & Gaining Electrons is Reduction). The oxidizing agent and reducing agent are the opposite of what is being ox...

Vivian Chang 3L

I'd definitely say do all the textbook problems and understand the concepts behind them! The textbook problems teach you a lot of concepts that weren't explicitly stated in lecture so I think it's super important to make sure you do them. Also, UA sessions are great for extra review and reinforcing ...

Vivian Chang 3L

I feel the same way! I try not to think about it because what's done is done and we can't really do anything about it anymore. I've been telling myself that I could use the energy to study harder for the final instead of worrying too. The best thing we can do for ourselves right now is to focus on w...

Vivian Chang 3L

For now, I'm planning to take Chem 14BL, LS7A, Spanish 3, and a GE. I'm not sure if I want to take 4 classes though so my plan is very subject to change.

Vivian Chang 3L

I'm not currently working a job but I did work part-time 9-15 hours a week from sophomore to senior year in high school and can relate to a lot of these comments. I stopped working when I started college (current freshman here :D) because I wanted to make sure I could adjust to the increased workloa...

Vivian Chang 3L

Hi! I unfortunately don't know of any additional resources like a Quizlet set but I'm happy to share what I like to do to prep! What I usually do before the midterms or final is call a friend and we'll basically take turns "teaching" the lecture to each other. We then make a study guide th...

Vivian Chang 3L

I am definitely super nervous for midterm 2. I feel like there was so much information packed within the second half of outline 3 and outline 4. I'm redoing sapling and textbook problems right now but I'm still not sure if I have an in-depth understanding of the concepts. Good luck to all of us for ...

Vivian Chang 3L

I make sure I get enough sleep every night and to take breaks when needed! Something I realized last quarter and this quarter is that if I'm burnt out, studying won't help me as much as it could because I'm not properly retaining the information. I would recommend starting your studying well in adva...

Vivian Chang 3L

I'm planning to take Chem 14BL next quarter because I'm trying to finish the Chem series as soon as possible! I also feel like it'll help to take Chem 14BL soon after taking Chem 14B and Chem 14A because the material will be fresher in your mind.

Vivian Chang 3L

Hi! To break it into simpler terms, the overall equation is ΔU = q + w, meaning the change in internal energy = heat + work. For heat (q), if pressure is constant, then you can say q = ΔH and therefore ΔU = ΔH + w. For work (w), you have the equations w = -P ex ΔV or w = -ΔnRT. If needed, you can al...

Vivian Chang 3L

Hi! To add on, temperature is constant during a phase change because all the energy supplied in the form of heat is being used to break the intermolecular/attractive forces between the molecules. For instance, if we're looking at the vaporization part of a phase change diagram, the temperature remai...

Vivian Chang 3L

Hi! I would definitely recommend studying well ahead of time so you don't feel rushed to cram all your studying in right before the exam. This really helps me with my anxiety because it gives me the time I need to practice the problems and go over the concepts until I'm comfortable with them. Also, ...

Vivian Chang 3L

I've found that doing all the textbook problems multiple times and fully understanding the concepts behind the problem-solving helps the most. I usually like to supplement this with going over the lecture notes carefully and attending UA sessions for more practice problems. I think the most importan...

Vivian Chang 3L

I took the rest of Friday off after taking the midterm! It was nice to take a little break from chem and just watch shows/nap in peace :)

Vivian Chang 3L

I think I probably spend 10-14 hours a week studying for chem but that's also because chem is my hardest class this quarter. I think part of the reason why I spend so many hours on chem is because it's a subject where you need to practice problem-solving to do well, so most of my hours spent studyin...

Vivian Chang 3L

Something I always remind myself to do is always take into account the number of valence electrons!! I did this in Chem 14A but when I was reviewing textbook problems for the Chem 14B MT1, I would always just draw only the bonds. This made me get the wrong answer a lot of the time because I wouldn't...

Vivian Chang 3L

I think you can only get partial credit on questions worth 10 points. For these questions, I think it would be like there are 2 answer choices that will give you credit: the right one will give you the full 10 points and the other will give you partial credit of 5 points. The partial credit answer o...

Vivian Chang 3L

Hi! You choose the value of R that has the units that align with the units you already have in the rest of your equation. For instance, if the problem gives you pressure in bars, you would use R=8.314 x 10 -2 L.bar.K -1 .mol -1 . If you were given pressure in atm, then you would use 8.206 x 10 -2 L....

Vivian Chang 3L

Hi! I used to have this problem a lot in the past so what I do now is if I get stuck on a problem or if it looks like it'll take a long time to work out, I'll skip it and come back later. I usually try to solve every problem at least once in the allotted time interval and I'll end up having at least...

Vivian Chang 3L

From my understanding, K can be used to represent either Kc or Kp. Since the table already gave another Kc column, I assumed that K was referring to Kp. I used the Kc value from the table because the values in the problem were referring to concentrations.

Vivian Chang 3L

Yes, this is true! Strong acids and bases dissociate completely so if you have, for example, 1.0 M of HCl, it implies 1.0 M H3O+ and 1.0 M Cl-.

Vivian Chang 3L

I think since Dr. Lavelle specifically said that only the textbook questions that he mentioned in his email will be on the midterm, we should focus on those for now. I did all the readings he mentioned for Week 3 and I wasn't able to solve the other 4D problems so I don't think we have to worry abou...

Vivian Chang 3L

You would get no credit for the question :( I would recommend asking for help on Chemistry Community or even some drop-in UA sessions so that you don't need to lose any HW points!

Vivian Chang 3L

I like to watch shows, eat, nap, or play with my dog to destress :)

Vivian Chang 3L

I think the only ones we need to know for this course are the strong acids H2SO4, HI, HBr, HNO3, HCl, HClO3, HClO4 and the strong bases are Group 1 & Group 2 metal oxides/hydroxides. Hope that helps!

Vivian Chang 3L

Hi! The general rule is when K is < 10^-4, to be safe. You should always check if your approximation is valid using the 5% rule too, which just means that if X is less than 5% of the initial concentration, the approximation works. Dr. Lavelle went over this in lecture so you can rewatch that too if ...

Vivian Chang 3L

One of my New Year resolutions was to start waking up earlier and so far, I'm doing better than I thought I would so that's a pretty good start! I also want to focus more on self-care because I have been stressed to the max these days, so I'm aiming to try out meditation.

Vivian Chang 3L

I have definitely had a lot of anxiety associated with this class, but I am honestly just a very anxious person in general. What really helped me is preparing VERY thoroughly for midterms/final. Reviewing the material over and over makes me feel like I am less likely to make careless mistakes on the...

Vivian Chang 3L

I would say try to focus at one task at a time and not be too harsh on yourself! Distance learning can be really hard for a lot of us, so we're already doing great just by keeping up with it. What I like to do is keep a calendar where I write down all my assignment due dates and test dates so I can ...

Vivian Chang 3L

I try to complete the outline problems as we go and I'll usually redo them 1 or 2 more times before the midterm/final. Doing the reading and assigned problems as we go helps me focus on understanding the topic thoroughly at one time. Also, it can get overwhelming completing some of the outlines beca...

Vivian Chang 3L

Like others have said, outlines 1 and 2 will definitely be on the midterm. I feel like only sections 4D.3, 4D.4, 4D.5, and 4E.3 from outline 3 will be on MT1 because those are the sections Dr. Lavelle said that we'll be covering this week in his email. In Chem 14A, I think Dr. Lavelle usually gave u...

Vivian Chang 3L

On that note, does anyone know if we will join a Zoom with our TA during the exam time for the proctoring session? I was wondering the same! I asked my TA and he said he'll get back to me with that info but as of right now, I'm still not sure. I feel like it would be the most reasonable approach to...

Vivian Chang 3L

If you were to write out the expression for the equilibrium constant for the overall reaction, it would be the product of the two K values of reaction 1 and reaction 2 (including cancelling out the same terms in the numerator and denominator). In short, the rule is just to multiply the two K values ...

Vivian Chang 3L

If you can fit it into your schedule, I recommend as many as you can, but attending at least once a week should be good! I've found that UA sessions are a good way to consistently practice the concepts so that you don't feel as stressed before the midterms/final because you've been reviewing the con...

Vivian Chang 3L

A study habit I've found to be really helpful is to start studying early! After every lecture, I review the lecture notes I just took to make sure I understand what we went over instead of cramming it all a few days before the midterms/final. I also like to spread out doing the textbook problems and...

Vivian Chang 3L

I've definitely been thinking a lot about switching majors since Fall quarter ended just because I'm not really sure what I want to do in the future yet. I do like science though so I'll probably stay within the Life Science majors, but I'm not sure exactly which major to pursue. Life science majors...

Vivian Chang 3L

Hi! What really helped me last quarter in Chem 14A was doing the textbook problems until I could do every problem correctly, attending UA sessions, and reviewing lecture notes carefully.

Vivian Chang 3L

Hi! What really helped me last quarter was doing ALL of the textbook problems (these are by far the most helpful prep I did), review lecture notes super thoroughly and make sure you understand concepts (not just how to problem-solve!!), and UA sessions. I would say if anything, try to finish all the...

Vivian Chang 3L

Hi! The textbook states "In general, if a chemical equation is multiplied through by a factor N , K is raised to the N th power." For b and c, technically yes, the reactions can simplify back down to the original equation given, but the expression for the equilibrium constant must match th...

Vivian Chang 3L

I think if you click on "Site info" on CCLE, you can find the TA zoom links (not all of them though because Dr. Lavelle said Lecture 3 is having a problem with zoom accounts so they haven't been posted yet). For Lectures 1 and 2, if you go onto Dr. Lavelle's website under "Course Mate...

Vivian Chang 3L

Adding on to the answer above, I also got (A), which was “One number that gives us information about the relative concentrations of reactant and product.” This is because the expression for K is the concentration of products over the concentration of reactants, or in other words, it tells us the RAT...

Vivian Chang 3L

Hi! I think it’s a typo and should be 2HD (g) —> H2(g) + D2 (g) instead. This way, there would be no change because both sides of the equation have the same number of moles of gas (2 and 2).

Vivian Chang 3L

Yes!! I also wanted to take the time to say thank you!! Thank you Dr. Lavelle, the UAs, and the TAs for taking the time to provide so many resources and to really encourage student learning! I never felt unengaged with this class because of how much student support there was, especially the UAs who ...

Vivian Chang 3L

I'm definitely going to enjoy sleeping in and watching a bunch of shows I've been putting off! Other than that, there were some new hobbies I wanted to try out/get back into so I'll be doing that too.

Vivian Chang 3L

Hi! Dr. Lavelle mentioned in lecture that both the -ido and -o are the same thing, except -ido is a newer notation and -o is the one we will mainly use in this course. So technically, both hexacyanoferrate(II) and hexacyanidoferrate(II) are correct. If the ligand ends with -ide, you change the endin...

Vivian Chang 3L

Hi! To add on to the post above, I don't think cisplatin was mentioned in the textbook, but it was discussed in lecture. To summarize, cisplatin is a chemotherapy drug used to stop cell division (and therefore prevent cancerous cells from rapidly multiplying). Cisplatin is square planar and has 2 Cl...

Vivian Chang 3L

I feel like I rely on both the textbook and lectures for learning because lectures give a good general overview on the topic and the textbook helps clarify any questions I have (even though I agree the textbook can be really dense in material sometimes). I also end up learning about a lot of things ...

Vivian Chang 3L

Hi! My TA told us that we're going to join a new link (I don't know if this is the same for all TAs) that is the same link all of her discussion sections are going to use. They're then going to split all the students among two breakout rooms where the TA will proctor one room and a helper will proct...

Vivian Chang 3L

I think I'm going to prioritize the review sessions on quantum and acids/bases because quantum was the biggest section and I don't fully understand acids & bases yet. I also feel like I forgot some stuff from the beginning of the quarter so honestly I'm going to try to go to as many review sessi...

Vivian Chang 3L

Like everyone else has stated, I think it definitely gets easier with a lot of practice! Also if you haven't already, memorizing all the ligand names, charges, and if they're mono-/bi-/tri-/etc. dentate really helps a lot. I actually don't know if we're suppose to memorize all that but it's really h...

Vivian Chang 3L

Yes! UA sessions are extremely helpful, but from what I've noticed, you have to find a UA that you feel fits your learning style. Some are faster-paced and some are slower-paced. You might like the way one UA explains a concept and not so much another. At the beginning of the quarter, I attended one...

Vivian Chang 3L

I've also heard some different things about whether it's 5 posts per week or just 50 posts by the end of the quarter, but I really think it depends on your TA. I thought it was 5 posts per week (because I think that's what it said on the syllabus) but yeah, I'd ask your TA just to be safe.

Vivian Chang 3L

Hi! For me personally, doing textbook problems, sapling, reviewing lecture notes, and attending UA sessions have prepared me really well for both midterms so I'll probably do the same for the final. Another thing I've found that has really helped me is when doing textbook problems, if you get a prob...

Vivian Chang 3L

I feel pretty good so far! I definitely studied really hard for the two midterms and it was worth it, but I just need to make sure I stay as motivated for the final. I've also been trying to attend more UA sessions than I usually do so that's helped a lot too.

Vivian Chang 3L

Hi! No, it would not make sense to have a smaller molecular formula mass than empirical formula mass because the empirical formula is the lowest whole number ratio of atoms. This means the molecular formula mass would either have to be the same as the empirical formula mass (if the molecular formula...

Vivian Chang 3L

I definitely felt like I did worse on MT2 than on MT1 :( I didn't feel as confident with my answers this time around but I'm hoping to make up for it by studying really hard for the final.

Vivian Chang 3L

Dr. Lavelle said on another post that he is not completely sure if the asynchronous lectures will continue next semester because there is a lot involved to keep it going. He recommends to avoid overlapping classes because Chem 14B could have tests during your lecture time.

Vivian Chang 3L

Like what everyone above said, I think everyone's final exam should be on the same day on Sunday, 12/13/20. The time listed on MyUCLA says 11:30am-2:30 pm so I think we would be taking it during this time. I think Dr. Lavelle will send out more details when we get closer to the exam date though :)

Vivian Chang 3L

I will occasionally go on a walk around my neighborhood or play with my dog in my backyard!

Vivian Chang 3L

To be honest this midterm stressed me out a lot more than MT1 :( I felt like it was pretty straightforward overall but there were a few questions that had me second-guessing myself.

Vivian Chang 3L

Yes sadly I think a lot of us are thinking about grades now after MT2 :( We can always balance points out with the final though so in a way, I guess this serves as motivation!

Vivian Chang 3L

Personally, I feel that textbook problems have been the most helpful way to prepare for the midterms so far. I try to do all the problems at least twice and if I get a problem wrong, I'll add it to a list so I can go back and do the problem again later on. I usually repeat this until I can do every ...

Vivian Chang 3L

"Have you heard that Oxygen and Magnesium are going out?"

" ... O Mg"

Vivian Chang 3L

Yup! You don't have to take Chem 14BL and Chem 14B at the same time. From what I've heard, I think a lot of people actually take Chem 14BL with Chem 14C because knowing the material from 14B ahead of time can be helpful for 14BL.

Vivian Chang 3L

I try to avoid reviewing all the materials at the last minute. Usually at the end of watching a lecture, I like to just look over my notes and make sure I have a good general understanding of everything that was discussed. For MT1, I did the textbook problems and made sure I knew how to do all of th...

Vivian Chang 3L

I think I remember Dr. Lavelle saying in one of the lectures that you don't need to memorize specific electronegativity values but you should be familiar with the trends for electronegativity.

Vivian Chang 3L

Hi! Studying from home can definitely be challenging but I think what's really helped me personally is planning out what exactly you want to accomplish on a particular day. For me, I keep an agenda of assignments I need to/would like to finish for the day, and I try to be as realistic as possible wh...

Vivian Chang 3L

I always make sure I start studying at least a few days in advance so I can prep until I feel like I'm ready/confident for the exam. What usually helps calm or reduce my anxiety is going through practice problems and making sure I know how to do all different types so if there's a similar question o...

Vivian Chang 3L

I'm doing okay! I feel like I've gotten a little more familiar with the quarter system now and overall, school hasn't been too bad. I do have to say though that I'm starting to feel the burnout these past few weeks, but I've been trying to make space in my daily schedule for some me time so that's h...

Vivian Chang 3L

Hi! I went to a UA step-up session today and he told us the exceptions to the octet rule that we need to know for this course are P, S, and Cl. I think Dr. Lavelle was going to go over this but the video cut off so he'll probably discuss it during tomorrow's lecture!

Vivian Chang 3L

To be on the safe side, it's a good rule of thumb to check formal charges when drawing Lewis structures so you can check whether or not the structure you drew is the most stable and therefore the more accurate representation of the molecule. An easier way to check formal charges (other than the form...

Vivian Chang 3L

Hi! Adding on to what the post above says, the inner core is composed of the shells that are already fully filled with electrons. This is why all elements in the same period share the same inner core. For instance, all elements in period 3 share the same inner core of [Ne] because they have the orbi...

Vivian Chang 3L

Hi! At Justin's workshop today, he said the exceptions to the octet rule that we need to know for this course are P, S, and Cl. This exception is possible because these atoms have an empty d orbital that can hold extra electrons. For example, sulfur has the electron configuration S: [Ne] 3s 2 3p 4 3...

Vivian Chang 3L

I'm not completely sure but I think he said during one of the lectures that we won't be working with the f orbital in this course.

Vivian Chang 3L

Adding on to what the posts above say, the Lewis structure is a "limitation" in terms of not representing the real structure of the molecule because there is actually no such thing as a double or triple bond. Instead, the real structure has bonds in between these lengths. This means that i...

Vivian Chang 3L

I also think Midterm 2 won't be cumulative because otherwise we wouldn't be tested much on the new topics we're learning (assuming we have the same number of questions we had on Midterm 1). I think the final would be cumulative though to test our full understanding of the course material.

Vivian Chang 3L

Since it says the light "excites" the hydrogen atom, we know the electron is going from a lower energy level to a higher energy level. Because 102.557 nm is in the UV light range, it is associated with the Lyman series and you know that one of the energy levels must be n=1. This problem in...

Vivian Chang 3L

The equation c=λv is used to find out the wavelength associated with a certain frequency of light (because if you think about it, c is the speed of light so this equation pertains specifically to light). If you wanted to find out the wavelength associated with a particle (a neutron in this case), th...

Vivian Chang 3L

Yup, the number of spectral lines corresponds to how many energy transitions are possible, so in this case you can go from n=7 to n=6, 7 to 5, 7 to 4, 7 to 3, 7 to 2, and 7 to 1, so that would be a total of 6 possible spectral lines. To find the wavelength range, you would find deltaE for the n=7 to...

Vivian Chang 3L

I think that was just a fun question not meant to be taken too seriously. This is kind of related to Heisenberg's Uncertainty Principle because if they want to resolve their uncertainties, they would either have to know the uncertainty in the momentum of their love, the uncertainty in the position o...

Vivian Chang 3L

I think both are good to know to fully understand the De Broglie equation conceptually. He went over how to derive it mathematically in a lecture or module (I don't remember which one exactly it was but he definitely mentioned it) so just in case, I would go over it. It isn't too complicated too so ...

Vivian Chang 3L

Yup, I think you just have to use logic with these types of problems. Regarding the speed of light, we know that nothing can be faster than the speed of light so anything greater than 3 x 10^8 m/s is impossible. I just looked back at my notes and found that I wrote "Typically, a particle with a...

Vivian Chang 3L

ellenulitsky Dis 2E wrote:I was confused by that too! So you multiply it by 2 so that it can be within the entire spectrum of uncertainty, which accounts for the positive or negative uncertainty?

Yup! The plus or minus means the value can range from (i.e. using v = 10 +-5 m, so deltaV= 10m) 5 to 15, which is a 10 m range.

Vivian Chang 3L

I think Dr. Lavelle meant up to section 1D.2 in the textbook, which includes energy levels and atomic orbitals (and stops right before quantum numbers). He also said that Midterm 1 will cover up to Wednesday of Week 3 for lectures and the lecture on Wednesday Week 3 included atomic orbitals so I thi...

Vivian Chang 3L

In this case, it would mean that Δx is literally 10Å. If it tells you + or - 10Å, then it would be 20Å.

Vivian Chang 3L

I think it depends on what the other units are for the equation you're plugging Rydberg's constant into and how it fits into that context. I normally just use 3.29 x 10^15 Hz for Rydberg's constant because I personally use the form of the Rydberg equation that has frequency (not 1/lambda) on the lef...

Vivian Chang 3L

I also got 9.7 x 10^-8 m like the above answer. I noticed sometimes when I use En=-hR/n^2 and subtract final - initial, I get the wrong answer, and I think it's because I always end up making a calculation error somewhere in between all the plugging in numbers into the calculator. Instead, I used th...

Vivian Chang 3L

Hi! I had a conceptual question about #39 on the Atomic Spectra Module Post-Assessment. 39) Calculate the wavelength of the radiation emitted by a hydrogen atom when an electron makes a transition from n = 4 to n = 2. I understand how to solve it but I just want to make sure I have a good conceptual...

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