CHEMISTRY COMMUNITY

Lisa Seidl 3H

I was confused about this section too. The textbook just seemed to mention it and not go into more detail but that article really helped. Thanks for sharing that!

Lisa Seidl 3H

This is definitely basic but Grey's Anatomy is my for sure comfort show. The second part of the last season airs tonight!

Lisa Seidl 3H

Why did the white bear dissolve in water? Because it was polar.

Lisa Seidl 3H

This quarter definitely went by so much faster than the last one! One thing I started in January was those little "one second every day" videos so keeping that up motivates me to do something fun everyday like go on a walk or get food or at least leave my apartment so that it's not the sam...

Lisa Seidl 3H

I made a whole list of like 12 clubs I was interested in at the start of the year, but I became very unmotivated and couldn't bring myself to spend more time on zoom than I already do with classes and all that. I will definitely be looking for clubs as soon as were in-person though!

Lisa Seidl 3H

I also agree with organic chemistry tutor. His videos are often pretty short and to the point. I will also occasionally watch some khan academy videos too along with their practice problems.

Lisa Seidl 3H

Chemical equilibrium and coordinate compounds were both kind of fun once I got the hang of it!

Lisa Seidl 3H

Thanks for starting this thread it's actually really helpful to hear about people's experiences in different clubs. I have found it very difficult to commit to clubs when the meetings are over zoom, and it doesn't seem like there's really any events worth my time, but I will definitely be joining mo...

Lisa Seidl 3H

I am pretty sure the value of n will vary, but this also confused me in the lecture on monday since I am pretty sure t=0 and ln[a]o=c but I am not sure if there is a set value for n.

Lisa Seidl 3H

I'm a freshman so I don't know much about what I have to look forward to. Mostly finding fun study places since that has always one of my favorite thing to do (especially going to little coffee shops and studying). Also, I am sooo excited to try like all the foods I've heard so many good things :))

Lisa Seidl 3H

My most effective way to study for this class has been to make review sheets that I try to limit to 1-2 pages condensing all the information that could be on the midterm/final so that I get a chance to go over it all again, write it in my own words and it usually helps me connect the different topic...

Lisa Seidl 3H

I really like the Organic Chemistry tutor on YouTube. I watch his videos often to understand trickier concepts since he is able to explain it differently than we may have learned in lectures or discussions.

Lisa Seidl 3H

What I did is I split the reactions into the two half reactions and then found their simplified forms on the appendix list. Make sure to keep in mind that the value for E^{\circ} is the same whether it is the oxidation half or reduction half even though only the reduction value is given. Then you ca...

Lisa Seidl 3H

I believe you would just use the coefficients from the formula. In other words, if you have aA -> bB + cC you would use the coefficients as the fractions. If a and b were both 2 and c was 3 then you would be able to find a common factor that you could multiply them all by to find these fractions for...

Lisa Seidl 3H

I was having this same problem. Every time that I tried to add the half reactions together they didn't seem to work with the coefficients. I felt like I was doing everything right and I made sure all equations were balanced, so I'm not sure what the right answer here would be.

Lisa Seidl 3H

I definitely had trouble with this one too! My suggestion is to start by balancing the Oxygens first and then the Hydrogens since if you do it the other way around you will end up with much larger numbers than you need. Hope this helps!

Lisa Seidl 3H

These are both deltaU values for mono-atomic ideal gases, so both equations can be used depending on if you want to find the molar internal energy with a constant volume or constant pressure. In addition to this, there are other R values for linear and non-linear molar heat capacity.

Lisa Seidl 3H

Make sure you add the Van't hoff equation to your equation sheet or print the new one for the exam too since he recently added it!

Lisa Seidl 3H

Another thing to keep in mind is that for the Gibbs Free Energy equation, the T must be a constant temperature and make sure your G, S, and H values are all in either kJ or J and your T is in Kelvin.

Lisa Seidl 3H

Did you hear about the man who got cooled to absolute zero?
He's 0K

Lisa Seidl 3H

This is only when no non-expansion work is done and the value for pressure is constant. In this case, if delta H < 0 the reaction is exothermic and if delta H > 0 then the reaction is endothermic.

Lisa Seidl 3H

I'm definitely feeling more nervous for this one too. I feel like I have a basic understanding of the equations and concepts but not like the "big picture" if that makes sense.

Lisa Seidl 3H

Im taking 14C and anatomy and communications and then debating on whether I should take an additional GE

Lisa Seidl 3H

I would also say to use your first pass! I don't know if they'll be offering 14C next quarter.

Lisa Seidl 3H

I tutor over zoom but had to limit my hours this quarter because I was having a hard time with this too. I try to plan out my work for the day and set small goals so that I know I will have enough time to achieve all my goals.

Lisa Seidl 3H

I was trying to find it too! Shazam and siri both didnt show any results :(

Lisa Seidl 3H

For the constant-volume molar specific heat, I'm pretty sure it would be given to us, at least the values relevant to the question. I don't think we would be expected to memorize this.

Lisa Seidl 3H

I think we are still on outline 3, it seems like he was going over topics from section 4B/4C in the textbook.

Lisa Seidl 3H

Helium walks into a bar,
The bar tender says "We don't serve noble gasses in here."
Helium doesn't react.

Lisa Seidl 3H

Q: What do you call a tooth in a glass of water?
A: One molar solution.

Lisa Seidl 3H

I'm not sure what you mean in your question, but in relation to work I would know the equations that he gave in his lectures this week (in relation to work) and how to derive them.

Lisa Seidl 3H

Oh wow thank you so much for posting this it actually really helped me feel better about my mistakes on the test too :)

Lisa Seidl 3H

Personally, I try to stay ahead of the lectures with my textbook notes since I find that it helps me understand the lectures better. They are like a review of what I read in the textbook. Then I will go back to that section and do the questions for it since I have all the knowledge from the lecture ...

Lisa Seidl 3H

I would suggest going over some acid/base background knowledge stuff that we didn't review this quarter just to have it fresh in your mind.

Lisa Seidl 3H

I was going to try to post some more chemistry jokes, but all the good ones argon!

Lisa Seidl 3H

I definitely relate to this too. I always try to think of my answer in the context of the problem and try to estimate what the value should be to make sure my answer makes sense. This is just kind of another way to double-check your answers, especially if you are running low on time and can't go ove...

Lisa Seidl 3H

I saw this too and I believe he briefly mentioned it in one of his lectures in week 2, but I couldn't find anything about it in the textbook readings. I would assume it won't be highly tested on since it was not a main focus of the course so far.

Lisa Seidl 3H

He said the midterm would only include everything up until friday of week 3. He also sent an email about which sapling problems and textbook problems would be similar to the ones on the test!

Lisa Seidl 3H

Yes, you can use any calculator (last quarter they preferred scientific but graphing is fine too) and then you will need to print the equation sheet on his website and the specific periodic table he has. They usually let you have 1-2 pieces of scratch paper (depending on the TA) and other than that ...

Lisa Seidl 3H

We will be able to use the equation sheet listed above and a periodic table and calculator so make sure to prepare those too!

Lisa Seidl 3H

Yes, from what I understood from the textbook, it doesn't seem like we would need to use anything more than the first protonation for a lot of them since the later ones are negligible but that would be the easiest way to solve it if you do have to use the other values.

Lisa Seidl 3H

For test questions I would assume that these would be given to us since in this case they are given in the table. But yes, here you use the links to the tables at the top of the question list for any questions that call for Ka or Kb values.

Lisa Seidl 3H

Enthalpy is dependent on internal energy, pressure and volume while temperature is just the intensity of the heat

Lisa Seidl 3H

It seems that we are finishing outline 2 this week since he said we will be moving on from acids and bases so my guess is that outline 3 would be included too but I am not sure. Hopefully we will find out soon!

Lisa Seidl 3H

For this problem, it requires energy to break the X-X bond in x^2 meaning that it is endothermic and absorbs the heat as energy for the reaction, shifting towards the products.

Lisa Seidl 3H

I believe what this means is that equilibrium within an aqueous solution can be shown by multiplying the concentration of cations in the aqueous solution by the concentration of the anions in the aqueous solution and that the solubility of the solvents in the solute can affect the equilibrium consta...

Lisa Seidl 3H

I was wondering if this would be the right place to post about any 14B related acid and base questions since this is in the 14A section. Is there a separate folder for 14B acids and bases?

Lisa Seidl 3H

For part c of 6a.19 on the macmillan textbook site, it lists the value as 3.1 mol/L but in the solutions manual it is listed as 3.1x10^-3 mol/L. I was wondering if this is an error or if I missed something in the steps to solve this problem.

Lisa Seidl 3H

This happened to me too, I closed the tab and reopened it in a new tab in chrome, and then it worked for me just make sure you are accessing the sapling link through CCLE!

Lisa Seidl 3H

Last quarter he posted them for only the first unit, so I'm assuming it will be the same this quarter.

Lisa Seidl 3H

When you are calculating for the equilibrium constant from the thermodynamics table (using Gibbs free energy for example) then you can only use K but other than that you can use Kc if you want to find the equilibrium in terms of molar concentration rather than partial pressure.

Lisa Seidl 3H

Kelly Singh wrote:This would be different than the K value right?

If this reaction is in equilibrium K and Q would be the same, so it depends on if it is in equilibrium.

Lisa Seidl 3H

Kelly Singh wrote:are "bars" an SI unit?

Bars are not an SI unit but they are the unit usually used to represent activity in problems like this

Lisa Seidl 3H

I don't think he would specifically ask about the experiment but definitely know just the general outcomes and concepts related to them since there are questions where you will need to apply those concepts.

Lisa Seidl 3H

Oh wow thank you so much I was looking for something exactly like this!

Lisa Seidl 3H

There's a page in the "Chempendix" in Macmillan listing all the strong acids and bases and how to identify weak acids and bases that really helped me memorize the important ones!

Lisa Seidl 3H

Aww this is so sweet thank you!! Good luck to everyone on the final, we got this :)

Lisa Seidl 3H

I was wondering if the final for 14A will be proctored the same way as the midterms were, meaning we join our TA's zoom and don't use the lockdown browser proctoring system? Also, would this mean that the zooms would have a lot more people in them since it would be all the discussion sections at the...

Lisa Seidl 3H

According to Dr. Lavelle's last email, Calculator, the Constants and Equations, his Periodic Table, and additional blank pages are
allowed.

Lisa Seidl 3H

I am currently taking notes on 9C.1 in the textbook and there is a whole paragraph about the calculations for finding the formation constant when solving for the equilibrium of a complex and it did not seem familiar from Dr. Lavelle's lectures. Is this something that is worth looking into more or wi...

Lisa Seidl 3H

Mine is pretty similar to the one mentioned before, but I use "Kings Hate Dragons Because Dragons Can’t Make Money" for Kilo, Hecto, Deca, Base, Deci, Centi, Milli, Micro.

Lisa Seidl 3H

What I try to do is the week before the exam I will attempt to summarize all the information that will be on the exam but limit it to 1-2 pages so that I have all the important information and then I reference that throughout the week to try to familiarize myself with it as much as possible. I also ...

Lisa Seidl 3H

I believe they had one other final available for international students in your exact situation! I would reach out to your TA and see if they can switch your time for you.

Lisa Seidl 3H

If you imagine a 3D atom, these are atoms that are in the same flat region. So if you laid the molecule on a table, everything that's coplanar would be at the same height if that makes sense.

Lisa Seidl 3H

I believe my TA said it depends on what the class average ends up being. So we would have to wait until the end of the quarter to see what grading "curve" he decides on, but that could be wrong.

Lisa Seidl 3H

I'm definitely having some trouble understanding this too. To my understanding, you just have to focus on what the basic electron density arrangement is (based on the VSEPR model) and then use the formulas to decide what the hybridized orbital state would be. For me, it helped when I understood that...

Lisa Seidl 3H

I had a question that related to this topic. Does the shape/complexity of the molecule not make a difference in the hybridization. Since C2H4 and C6H6 have the same hybridized orbitals (sp^3) does that mean that we somehow have to clarify how many times this repeats and does that change the hybridiz...

Lisa Seidl 3H

There is no school Thursday or Friday so my assumption is there will not be any mandatory discussion sections or lectures.

Lisa Seidl 3H

This is because H2O is a bent shape, as he mentioned in Wednesday's lecture. If it was linear then the lone pairs would be the furthest away from each other at opposite ends, but since an angular/bent shape with a tetrahedral arrangement based off of electron density makes more sense here, the lone ...

Lisa Seidl 3H

I don't think we need to know that equation since he did not go over it in lectures and it isn't on the formula sheet or in the Quantum World outline. From 1D.4 I would just focus on the shapes of the different types of subshells and how many nodal planes they have and you should be fine.

Lisa Seidl 3H

I was confused about this too. I think it has to do with the polarity of the atoms in the molecule and how strong their pull is especially if they don't follow the octet rule (radicals, expanded octets, etc.). Hopefully someone else will answer that can expand on this a little more!

Lisa Seidl 3H

I don't think so, no. At least not yet. We learned about expanded octets, radicals coordinate covalent bonds so if you know those you should be fine for now.

Lisa Seidl 3H

I was going over my textbook notes and reviewing old topics from the quantum world outline that were said to be covered on midterm 2. Within this section, I had trouble understanding the concepts in section 1D.1 (Energy Levels) and 1E.1 (Orbital Energies) and they didn't seem to be in any of the lec...

Lisa Seidl 3H

Yes, I noticed this same mistake. It seems like the bottom of the image was cut off in the sapling version of the textbook but the answer key model should be the right one.

Lisa Seidl 3H

So this is the same thing as an Induced Dipole - Induced Dipole interaction where the two molecules interact with each other and thereby become induced dipoles creating partial negative and positive charges on opposite sides that fluctuate.

Lisa Seidl 3H

I was a little confused about this too. I am pretty sure that this value is the dissociation energy needed to break the bond ( E_{D} ). However, Dr. Lavelle said this value is always positive, so I am not sure why it was negative at the end for Ion-Ion attractions as well as Ion-Dipole, Dipole-Dipol...

Lisa Seidl 3H

An element will have a delta + charge if it has less valence electrons in a molecule than it should according to the periodic table. Since there're fewer electrons there is a positive charge. The opposite is also true where if there are more electrons in the molecule than listed on the periodic tabl...

Lisa Seidl 3H

I was doing the questions for section 2D in the textbook and there were a lot of questions asking about the electronegativity of certain molecules/compounds and you were asked to compare them. Since we have the rule that if the difference in electronegativity must be >2 for an ionic bond and <1.5 fo...

Lisa Seidl 3H

Another way to tell is if the total amount of valence electrons is an odd number since that would mean that there is an unpaired electron.

Lisa Seidl 3H

Chem_Mod wrote:Oxygen is more electronegative than Chlorine, so it wants electrons more, making Chlorine the radical!

Oh got that makes sense thank you!

Lisa Seidl 3H

I had a question about part a of this question which is: Draw the Lewis structure of each of the following reactive species, all of which are found to contribute to the destruction of the ozone layer, and indicate which are radicals: (a) chlorine monoxide, ClO I know that this will be a radical sinc...

Lisa Seidl 3H

I found an inconsistency in my notes about this example, and I was hoping for some clarification. In my notes on the lecture from today, Dr. Lavelle seemed to show the BF3 molecule like this (the handwritten image) However, in the textbook this same example is given, and they explain the correct str...

Lisa Seidl 3H

In the textbook (section 2C.2) it said that atoms can potentially accommodate 10, 12 or more electrons in an expanded valence shell so it doesn't seem that there is a limit it just depends on the element.

Lisa Seidl 3H

Yes, he just mentioned in his discussion section that finals will cover all material from both midterms as well as the material after midterm 2.

Lisa Seidl 3H

I'm not sure what category this would fall under, but I am planning out my schedule for next quarter and will be taking chem 14b, and I was wondering if that class will have the same format with video lectures and Zoom discussions? I really enjoy being able to pause the videos and go back while taki...

Lisa Seidl 3H

Electron affinity is always the change in energy (increase) when an electron is added to an atom (making it an anion). A higher electron affinity means that the element will more readily accept an electron, so yes, you could say it wants to gain an electron more than other elements with lower electr...

Lisa Seidl 3H

For these it seems like we can only shorten them up to the noble gases. So you would say that Carbon has a "helium-like core" and then the additional 2s^2 2p^2 would be the valence electrons. So basically, you can only "simplify" it to the noble gas elements such as He, Ne, Ar, K...

Lisa Seidl 3H

Hi! So n=7 and l=1 means this element is in the 7p subshell and has 6 possible electrons, like you said. However, the ml value is significant, because for the p-subshell there are 3 possible orbitals (-1,0 and +1) This means that since the ml value can only be +1, there is only one possibly orbital ...

Lisa Seidl 3H

What do you call an acid with an attitude?

A-mean-oh acid

Lisa Seidl 3H

The original equation is (lambda)=h/mv
To rearange this, you'd want to solve for v before inputting any numbers since this makes the process a lot easier. After rearranging and solving for v, your new equation should be v=h/m(lambda)

Lisa Seidl 3H

So I was hoping to get a little clarification on the differences between the Rydberg equation from the textbook ( v=R\left \{ \frac{1}{{n_{1}}^{2}} \right \}- \left \{ \frac{1}{{n_{2}}^{2}} \right \} ) and the equation given to us in lecture on Friday ( E_{n}=-\frac{hR}{n^{2}} ) I was under the impr...

Lisa Seidl 3H

I had a question about the general format of the midterms since I believe Dr. Lavelle said in his office hours that the test would be multiple choice, but he previously mentioned that we will receive partial credit for questions so how does this work? Will we have to submit a PDF of our work for eac...

Lisa Seidl 3H

Yes, this helps control any other variables and otherwise the electrons will hit O2 or H2O molecules in the air, and might not be read by the electron detector.

Lisa Seidl 3H

Initially, it was believed that increasing the intensity of light (in photons) would cause more electrons to be removed, but the photoelectric experiment showed that it was the frequency of the light that affected if light electrons were ejected from a metal, not the intensity.

Lisa Seidl 3H

Not sure if you saw this, but he did update his policy! You can log into zoom on another device (like a phone or tablet) and use that as your external camera so that you don't have to buy a new one.

Lisa Seidl 3H

I had some trouble with this question too, so I'm glad you brought it up for clarification. To my understanding, this question was asking about what makes all the values in the Balmer series or Lyman series similar, as in why are they grouped together. After reading section 1A.3 it talked about how ...

Lisa Seidl 3H

I'm not sure if this has been asked yet but I couldn't find anything specifically about this. For the midterms (and eventually the final) are there any calculators that we cannot use. I read something about not being able to use one that can store text but I'm not exactly sure what that would mean. ...

Lisa Seidl 3H

1A.7 (a) The frequency of violet light is 7.1x10^14 Hz. What is the wavelength (in nanometers) of violet light? (b) When an electron beam strikes a block of copper, x-rays with a frequency of 2.0x10^18 Hz are emitted. What is the wavelength (in picometers) of these x-rays? For part b of this questio...

Lisa Seidl 3H

After today's lecture on photoelectric effect I'm trying to wrap my brain around the differences between this and the wave model from last class. Do the findings from the photoelectric effect, about the frequency of light affecting whether electrons are emitted, make the wave model somewhat outdated...

Lisa Seidl 3H

I believe he does want us to write the states of matter since that is how they are listed in the textbook questions and that is where he gets the test questions from. However, I would think that he would probably specify if he wants them or not in the question (for tests), but on the homework I woul...

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