CHEMISTRY COMMUNITY

Anna Martin 2l

I go back and forth for this one. Personally, I love to take handwritten notes simply because I feel as if it makes the information stick more and I like being able to draw diagrams or pictures on paper better. But, I think that notes on an iPad or computer, using apps such as notability, can be a g...

Anna Martin 2l

I found this YouTube video where he was able to describe the concept very well and made it very easy to comprehend! I was able to understand it a lot more even after a few minutes.
https://www.youtube.com/watch?v=7b34XYgADlM

Anna Martin 2l

Does anyone know how we would approach this question differently for 9 and 10, when it is second-order and first-order?

Anna Martin 2l

Burnout is definitely a real thing and can be something extremely hard to avoid. I usually try to find ways to destress and find things that I enjoy that I can distract my mind from.

Anna Martin 2l

As stated above, I think that the final will be of a majority of the newer content that we learned after MT1 and MT2, but we will still need to know everything that we have learned thus far. That's what it was like in 14A so I think it will be about the same.

Anna Martin 2l

I love burritos and basically any Mexican food!

Anna Martin 2l

I believe if the E is positive, then it will proceed in the forward direction and be positive.

Anna Martin 2l

It's definitely about prioritizing your time to attend workshops and complete textbook problems. I would also recommend reaching out to TA's or UA's if you're confused about a problem, because they're super helpful in conceptually understanding the problem or subject. Good luck everyone!

Anna Martin 2l

No I don't believe you would need half reactions because the charges don't change.

Anna Martin 2l

Basically, as long as you do at least 5 posts per week then you will get the full 50 points and you cannot get extra credit for more posts.

Anna Martin 2l

Now that all of my midterms are over, I am definitely going to be spending some time outside, whether it be hiking, going on a run, or just enjoying nature. Studying for midterms and catching up on my assignments has caused me to be cooped up in my apartment, but hopefully now I will have some time ...

Anna Martin 2l

Thank you this helps a lot! I was getting them mixed up so much but this actually helped me remember them.

Anna Martin 2l

I am currently considering to work during next quarter, and reading this thread was extremely helpful! I think that already school can be very stressful and time-consuming, and I have had a hard time deciding whether or not I should get a job. But, I think that it just boils down to your own time-ma...

Anna Martin 2l

Reducing agents are elements in which they can lose electrons and be oxidized and oxidizing agents can gain electrons and be reduced. For example: Zn + S -> ZnS Oxidation: Zn -> Zn2+ + 2e- Reduction: S + 2e- -> S2- In this reaction, Zn is the reducing agent, in which it undergoes oxidation and obtai...

Anna Martin 2l

In this problem, you are basically putting these half reactions together into one reaction. So, you would have to balance the number of electrons on each side in order to do sum them together.

Anna Martin 2l

I agree with many people above that studying and trying to stay focused is really hard nowadays. What I try to do is to set aside time for my day to relax and not worry about school, but other times to do assignments and study. If you plan your day around that, instead of waiting until the last minu...

Anna Martin 2l

Hi! So basically for this problem you want to first convert Celsuis to Kelvin. Then, you want to calculate n (moles) with PV=nRT equation and use the values of moles to find the molar heat capacity. Then, use the equation, ΔS=CVln(T2T1), to find the change in entropy and you should get the answer! H...

Anna Martin 2l

I definitely agree, I am pretty nervous! This course can be very difficult and time-consuming, but I have been trying to keep up with the work by attending workshops and looking over homework problems. The only thing we can do at this point is prepare and have a positive mindset!

Anna Martin 2l

As stated above, n means "moles." But, it depends on the units in your equation because sometimes you can use grams in the equation.

Anna Martin 2l

So, you basically have to divide it into steps. First, you have to calculate the entropy for the change in volume using the equation, ΔSV=nRln(V2V1). Then, you have to calculate the entropy for the change in temperature with the equation ΔST=CVln(T1T2). To find the ΔS total you just have to find the...

Anna Martin 2l

What would people recommend about taking Chem 14C and Chem 14BL together? I am planning on taking Chem 14BL next quarter but wasn't sure if I should also take Chem 14C, or if it would be too much work altogether. If someone has an idea about what they're planning on doing or what they would advise p...

Anna Martin 2l

So for path A, you would first need to use the Ideal Gas Law (PV=nRT) to find the moles of gas. Then, you would use the equation: w=-nRTln(Vf/Vi), because it is a reversible, isothermal equation to find the work. For part B, because it is two steps, you would just need to add the two values of work ...

Anna Martin 2l

If there are more moles of gas on the product side then the reactanct side, then the change in volume is positive. A(s) + B(s) -> C(g) does work on surroundings because it produces more moles of gas than they consume.Therefore, in the equation w=-PΔV, the value of work would be negative because the ...

Anna Martin 2l

For this question, I was just confused on how you would find the change in volume. I found the volume using the Ideal Gas Law, so would you just use that value in the work equation of w=-PΔV?

Anna Martin 2l

Yes, I believe that it is the same way we learned through VSEPR in 14A!

Anna Martin 2l

I was also confused on this, but I think you do products minus reactancts when given enthalpies of formation like you said. But I could be wrong!

Anna Martin 2l

Last quarter it took about a week for scores to come out so I would guess that it would be around the same time for this quarter!

Anna Martin 2l

So for this problem you know that 1 mol of S8 is required for the heat absorbed to be 358.8kJ. So, if you have 1.31 mol of S8, you would just have to multiply 1.31 by 358.8kJ to find the amount of heat absorbed at 1.31 mol.

Anna Martin 2l

Bond enthalpy is the energy required to break the bonds, therefore if the molecule has a higher bond enthalpy, then it requires more energy to break its bonds and is more stable!

Anna Martin 2l

I believe that PJ is just the pressure of whatever "J" is, and nJ is the amount of moles of J.

Anna Martin 2l

It says above to use the tables for Ka and Kb, so I think you can if I'm not wrong!

Anna Martin 2l

Hi! I would definitely recommend to start by reviewing lectures/your lecture notes to start from the basics! Then I usually apply what I reviewed to textbook and Sapling problems to get used to the type of the questions that may be asked on the exam! Then I will try to attend as many UA sessions or ...

Anna Martin 2l

Yes, like said above, it is determined based on initial concentration and as well as if the Q value is bigger or smaller than the K value. If the K value is larger than the Q value, then the reaction favors the forward reaction, where the products are subtracted by X. If the Q is bigger than the K, ...

Anna Martin 2l

HI! For this textbook problem I may have just calculated it wrong, but I found the Ka to be .107 and the pKa to be .97, but the solutions manual says that the Ka is 0.09 while the pKa is 1.0. I first found the concentration of H3O+ to be 0.063 from the pH, and then set up an ice table and used the 0...

Anna Martin 2l

I looked over my notes and in this problem you are dividing 10^14 by 1.8 x 10^-5, which if you put in the calculator equals to 5.6 x 10^-10. I think that you just forgot the negative in the exponent for 1.8 x 10^-5. Hope this helps!

Anna Martin 2l

I think that it's all about prioritization and what you keep in your life most important. Obviously, there needs to be a balance but it's also really difficult to find and maintain that balance! Usually, if I am having trouble focusing on school, I try to space out time in my week that I devote sole...

Anna Martin 2l

For this problem, I am having a hard time trying to figure it out. Could someone help me with how they figured out which equations to use and how they used them to find the answer. Thanks!

Anna Martin 2l

I started by creating an ICE table, with the products' initial moles being 0. Then, from the information given about 02, I found out what the X value is, and used the stoichiometric coefficients to find the final moles of all three molecules. I then found out the molar concentration of each molecule...

Anna Martin 2l

Yes! That would be super helpful!

Anna Martin 2l

I am still kind of confused on how to solve this question. I think that I am getting the wrong value for X, and I am pretty sure that I am setting up the ICE table right but it may be something to do with an error in my calculations. If anyone who knows how to do this problem could help me out with ...

Anna Martin 2l

I agree with what was said above! I believe that the content should mainly be directly from the syllabus. But, since this is a continuation course from 14A, it will include information from 14A material. Hope this helps!

Anna Martin 2l

I believe they both pretty much mean the same thing!

Anna Martin 2l

For now, I don't think it's necessary to know the certain amount of time needed to reach equilibrium for problems!

Anna Martin 2l

I believe the 1.75 should be squared instead of cubed.

Anna Martin 2l

I would assume that there would be fewer points, but I would check the syllabus for sure.

Anna Martin 2l

Before I study, I love to play a upbeat song that will get me motivated to study, and then while I am studying I look up "background music for studying" on YouTube and choose one of those videos to help me stay focused.

Anna Martin 2l

I am planning on taking advantage of this time to relax as much as possible as well as spend quality time with my family:)

Anna Martin 2l

I believe you count both lone pairs and bonding pairs because they are both considered regions of electron density!

Anna Martin 2l

I was also confused on this! I just googled it and it says that electron promotion is when an electron absorbs a photon to jump from a low energy level orbital to a higher one.

Anna Martin 2l

I think the questions in the review lectures were mainly to review the concepts but were also taken from past exams. Like everyone else said, a lot of the midterms in the past had questions from the textbook so I would focus on those too!

Anna Martin 2l

I think oxidation number is just the total number of electrons that an atom gains or loses to form a chemical bond

Anna Martin 2l

I am definitely going to take advantage of all the review sessions these week as well as Professor Lavelle's review session. I think it is super helpful to do practice problems with other students and be able to ask the UA's questions while doing so!

Anna Martin 2l

So atoms outside the brackets do not have prefixes?

Anna Martin 2l

Thank you so much! I would also recommend Khan Academy as a great resource for step by step videos and extra information :)

Anna Martin 2l

For the second part of question 3 of sapling, it asks: Which geometry or geometries are common for complexes with a coordination number of 6? trigonal bipyramidal hexagonal planar octahedral pentagonal pyramidal I assumed that the answer would be hexagonal planar, octahedral, and pentagonal pyramida...

Anna Martin 2l

I think that it can go either way but I would recommend sticking to the sp^3d method because that's orginially how Professor Lavelle taught us!

Anna Martin 2l

I got the same thing as you did for that question and was also confused why the book gave that answer instead!

Anna Martin 2l

I downloaded the textbook through the Bookshelf application and I am able to see the problems completely. If you have access to Bookshelf I would recommend installing the book through that! I included 2E.15 below :)

Anna Martin 2l

I wouldn't say that they are considered incorrect, but I believe that the most ideal or correct structure is the one with the least amount of formal charges on the atoms.

Anna Martin 2l

Why are delocalized pi bonds only found in resonance structures?

Anna Martin 2l

I think that lone pairs have a greater repulsion strength because they occupy more volume!

Anna Martin 2l

I believe two pairs in a linear arrangement should always be about 180 degrees apart.

Anna Martin 2l

For this past midterm, I found that rewatching lectures about concepts I did not fully understand helped a ton! I was able to relearn the concept and review it from the very beginning, step by step. You can even put the speed on 2x so it is not as time-consuming. After watching the lecture, I would ...

Anna Martin 2l

Yeah, I would agree with what was said above. Just remember that lone pairs are the most repulsive because they occupy the most volume!

Anna Martin 2l

Could covalent bonds be a part of this list?

Anna Martin 2l

Thank you for doing this I love this idea! I just wanted to remind everyone to relax and take a deep breath as well as to stay focused but also give ourselves a break :) We are all going to do great!

Anna Martin 2l

I believe for what we have learned so far, that hydrogen bonding should only occur between N, O, and F atoms because of their electronegativity.

Anna Martin 2l

I believe that "bond character" just simply means the nature and characteristics of the bond based on what type it is (covalent, ionic, etc.).

Anna Martin 2l

For the question #13 of the Sapling homework, how would you determine how many water molecules that the Urea molecule can hydrogen bond with?

Anna Martin 2l

Ok I was also confused on this question and got exactly what you got! Would that just mean if the charge is -2, we would have to include the number 2?

Anna Martin 2l

Thank you so much for putting this together its super helpful:)

Anna Martin 2l

Hi! I have also found prioritizing studying to be a huge challenge from learning at home. What has helped me a lot is to set a schedule and plan my day for when I allot time for work and when I get free time. Additionally, I find that going into a new environment, even outside my bedroom or out of m...

Anna Martin 2l

Yes, you do need to assign formal charges but I don't think it matters in what direction the bond pairs are.

Anna Martin 2l

Hi! I believe that elements in the same group have similar properties and are grouped based on the number of valence electrons they have, so I believe the number of electrons they have do determine similar properties. Hope this helps!

Anna Martin 2l

Hi, I was just wondering if anyone could clarify how to figure out where the negative sign goes when constructing a lewis structure, whether it's outside the molecule or on a specific element. Thanks!

Anna Martin 2l

I don't think anyone has mentioned if we will need to, but I would assume that we should start at least familiarizing ourselves with the patterns just in case.

Anna Martin 2l

So has anybody yet received their score for the midterm? Haven't all discussion sections taken it as of today? I have not received my score yet and I don't think they are out currently, but they probably be released soon because all of the discussion classes have taken it. They might just be sortin...

Anna Martin 2l

I also struggle with staying focused on homework and assignments or even in class having online instruction. I have found what helps is to remove any distractions, such as my phone, and place them out of reach so I will not be inclined to stop what I am doing. Also, I find that setting a schedule fo...

Anna Martin 2l

Hi! I agree with what Sean said about not needing to know the specific cutoffs of the EM Radiation Spectrum. You should mainly focus on trying to comprehend the main concept of it and the inverse relationship between frequency and wavelengt as well as the Lyman and Balmer series. Hope this helps!

Anna Martin 2l

In Lecture 12, Professor Lavelle was discussing the concept of ionization energy across the periodic table. I was just a little bit confused and wanted a little bit of clarification of why the ionization energy increases left to right across the periodic table but decreases down a group. If anybody ...

Anna Martin 2l

The Balmer series is the visible light region, where n=2, and it has wavelengths between 400 and 700nm. On the other hand, the Lyman series is the UV light region, where n=1 and has shorter wavelengths than the Balmer. I believe it is important to understand and remember these characteristics that w...

Anna Martin 2l

For #9 on 1B for the textbook homework it asks this: A lamp rated at 32 W (1W = 1 J.s^-1) emits violet light of wavelength 420 nm. How many photons of violet light can the lamp generate in 2.0s? How many moles of photons are emitted in that time interval? I was just a little confused about how to fi...

Anna Martin 2l

Hi! So the equation is V= R[(1/n2 - 1/n2], but the problem asks for wavelength instead of frequency. Because we know that c = wavelength x frequency, we know that V =C/wavelength. So, they just simplified it by replacing V with C/wavelength and isolating the wavelength by dividing both sides by C (2...

Anna Martin 2l

I believe you should round to 2.719 for sig figs!

Anna Martin 2l

When you are finding the wavelength of something that has mass is when you should be using de Broglie, like an electron or an object. Therefore, you cannot use this to calculate the wavelength of photons because they have no mass and must use the other equation to find the wavelength of light.

Anna Martin 2l

I also had the same question as you and was a little confused about this. But, I believe that in the lecture, he talked about how the energy of the photon must be greater or equal to the energy needed to remove the electron. So, as long as it is at least equal to the energy, then it should be able t...

Anna Martin 2l

I agree with everyone above to take advantage of the resources available, such as the modules as well as the step-up and workshop sessions. Entering this chem class with having little chemistry knowledge, I have found that continuing to practice and put my time into attending these UA sessions have ...

Anna Martin 2l

Hi! In the lecture, the professor was talking about how the energy gaps get smaller, for example the energy gap between n=1 and n=2 is the largest, while between n=2 and n=3 it gets a little bit smaller and every gap after continues to get smaller. I was still just a little confused about this topic...

Anna Martin 2l

I may be wrong, but I thought that as long as the energy of the photon is equal to or greater than the energy needed to remove the electron, then the electron would be ejected. But I also had the same question!

Anna Martin 2l

Hi! I agree that iPad notes are a very easy and useful source to organize your notes and have everything all in one place, but it really depends on what your learning style is! I love physically having my notes in front of me to flip through as well as writing down the notes and drawing the diagrams...

Anna Martin 2l

In questions E9 of the fundamentals unit, I was just confused about when it asks in question b to determine the formula units. I remember learning about them in high school chemistry, but I was just wondering if anyone could help clear about the definition and the difference between formula units an...

Anna Martin 2l

You are able to do this because in the problem because it is given that there is 1g of the original sample, made up of carbon, hydrogen, and oxygen. Because of the law of conservation of mass, matter cannot be created or destroyed in chemical reactions, therefore, 1g of that sample carries on to the...

Anna Martin 2l

When balancing chemical reactions, is there a specific order that you should go in or does the order not really matter and does it mainly depend on the reaction itself? I've heard that it is a good strategy to go in the order of balancing C, then H, then O, but I am not sure If that is completely ne...

Anna Martin 2l

I am assuming a periodic table and information needed will be available to us in an online version during exams, similar to how the Sapling website gives us access to those resources. But, I am sure your question will be answered by the professor when we get closer to the exam!

Anna Martin 2l

For question 9 of the sapling homework, I seem to have completed the beginning steps of the problem correctly, but I cannot figure out how to calculate the empirical formula at the end. I think where I am lost is when I have found the correct number of grams of C, H, and O, but I need to convert the...

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