CHEMISTRY COMMUNITY

Rayna Irving 2C

Can you do anything to affect the frequency factor in the Arrhenius Equation of a reaction (like increase the in temperature), or is it just seen as specific to each reaction?

Rayna Irving 2C

Quick question, do we ever include water when writing a rate law equation?

Rayna Irving 2C

What are the main differences between a galvanic cell and a concentration cell?

Rayna Irving 2C

I still don't really understand what a salt bridge does, can someone please explain it?

Rayna Irving 2C

Under what circumstances does ΔU = 0?

Rayna Irving 2C

I've heard that we should be done early with the material, which I assume means by Wednesday, and if it's anything like 14a Friday would be a review lecture going over material we learned over the whole quarter.

Rayna Irving 2C

How does the rate constant, k, depend on activation energy? For example, if the activation energy for a reaction is high, what does that tell us about k?

Rayna Irving 2C

What's the difference between something being kinetically stable vs something being thermodynamically stable?

Rayna Irving 2C

Conceptually, what makes something a slow step verses a fast step? Does it have to do with activation energy or something else?

Rayna Irving 2C

I've been feeling the same way for a while too. The best advice I could give you is to try and go outside even if it's only for a couple minutes just to get some fresh air and not feel so trapped inside. I also like to give myself small rewards (whether that be watching a show, playing a game, or bu...

Rayna Irving 2C

Step-ups make sure that you have the basics of whatever topic that we're focused on that week, while workshops are more application and problem-solving based. If you think that you're still shaky on a certain topic, I'd recommend going to step-ups and once you think you have it down, try out a works...

Rayna Irving 2C

In general, what are some of the key characteristics to look for when trying to differentiate which substance is the anode and which is the cathode?

Rayna Irving 2C

On sapling question #17, why is it that we can use the partial pressure and the concentration in the same Nernst equation when calculating Q?

Rayna Irving 2C

I'd definitely prioritize textbook questions and studying as early as possible so everything doesn't feel so overwhelming on the last week. UA sessions also help to get used to the variety of questions and to make sure you can strengthen any weak spots.

Rayna Irving 2C

Why is it that when using standard reduction potentials, we do not multiply that value by the coefficient in the equations we are given?

Rayna Irving 2C

I would guess in about a week but he usually emails us to give an exact date and time so I'd keep a look out for that.

Rayna Irving 2C

Since we didn't do that many problems that had to do with the Van't Hoff Equation, I was wondering in what situations would we use it? What do we use it to find?

Rayna Irving 2C

How do you know if a system is thermodynamically stable or unstable? What do I look for to determine my answer and how does Gibbs Free Energy factor in?

Rayna Irving 2C

I try to go through the outline and find the concepts that I don't understand and review notes and YouTube videos on that particular topic until I understand it. I usually do this before I start doing actual problems so it's less pure memorization and more focused on application and truly understand...

Rayna Irving 2C

Congrats and good luck on the next couple of weeks !!

Rayna Irving 2C

Most of what we've been studying, like enthalpy and Gibbs free energy, have been state functions, so I was wondering if there was anything for this midterm that we need to know isn't a state function?

Rayna Irving 2C

I don't think so because I think we have to just know how to derive it using the equations we're given on the equation sheet.

Rayna Irving 2C

Thank you so much for the tips! I do the same thing with the textbook problems because I find I forget the problems and how to solve them if I do them too early.

Rayna Irving 2C

What's the difference between an isothermal process and an adiabatic process?

Rayna Irving 2C

Quick question, how is G°different from just G?

Rayna Irving 2C

What's the key difference between a closed and an isolated system and can you give examples of each?

Rayna Irving 2C

I'm feeling the same way, I'm going to focus more on trying to make room for more UA sessions and to do the textbook problems as I go instead of waiting until the end.

Rayna Irving 2C

On one of the sapling problems, there's a hint that asks what the relationship between Cv and Cp is, and I was wondering if we went over it in class or if someone knew what it was, and when to use one vs the other.

Rayna Irving 2C

How do you know when to use the w=-P(ext)*(deltaV) equation and when to use the w=nRT(ln(V(final)/V(initial)) equation? Like, are there any key phrases or information I should look for when trying to decipher which to use?

Rayna Irving 2C

Quick question, how do you know when work is a positive or negative value?

Rayna Irving 2C

Hi, I haven't really been understanding the material for thermodynamics lately, so does anyone have any recommendations for outside resources to help me comprehend it better?

Rayna Irving 2C

Can you guys name some ways to tell if a compound is a weak acid or a weak base just by looking at the formula when trying to calculate equilibrium concentrations, I've been having some trouble with that.

Rayna Irving 2C

Why is it that we can add pka + pkb to get pkw but we have to multiply ka and kb to get kw?

Rayna Irving 2C

I feel the same way. I've found planning out my work schedule including breaks and journaling my feelings in a stream of consciousness way helps a lot with balance. Doing something I enjoy for some time in between each assignment or class has also helped bring down my overall stress level. Don't fee...

Rayna Irving 2C

I totally agree with the textbook thing. I find myself rereading sections over and over again because I can't seem to focus with that much information on one page lol. Thanks for the study tips too, I try to incorporate them into my study routine!

Rayna Irving 2C

I don't think I did that great either but I also realized that this one midterm doesn't determine my future. To unwind I mostly just watched some of my comfort shows and chat with my friends.

Rayna Irving 2C

Kelvin because in this case the rate, R, is a value that corresponds with the unit Kelvin.

Rayna Irving 2C

There should be a section on Lavelle's website that gives both the equation sheet with equations and other info we are allowed to use on the test, and the periodic table we can use, so I suggest printing that out before Friday.

Rayna Irving 2C

Yup I'm pretty sure we can use any calculators because I haven't heard about any restrictions regarding this so far.

Rayna Irving 2C

I'd definitely focus on reviewing your notes and doing as many textbook problems as possible.

Rayna Irving 2C

Would it be better to always calculate the % ionization instead of just relying on k being less than 10^-4 when checking if you can approximate concentrations?

Rayna Irving 2C

Do we only use the ionization constant for water, Kw, when trying to find the concentration of [H30+] and [OH-] of strong acids/bases, or are there other uses for it?

Rayna Irving 2C

The R value we use just depends on what units the question gives, and I believe we will be given a list of all the possible R values and what units they correspond to on our equation sheet.

Rayna Irving 2C

When simplifying quadratic equations, which value of K signals that it is okay to do instead of the quadratic equation: 10^-3 or 10^-4?

Rayna Irving 2C

I usually just try to keep track of my posts myself because we don't know when exactly TA's will update chemistry community grades (weekly vs. all at once at the end) but you can keep checking on the grades tab in CCLE in the mean time.

Rayna Irving 2C

Just checking but is temperature the only thing that can change the value of K?

Rayna Irving 2C

Q and K are found the exact same way with the ratio of products/reactants, but K is just specifically referring to the value when the reaction reaches equilibrium.

Rayna Irving 2C

I'm pretty sure we use atm because its units line up with the R value we are given on the equation sheet so the units can cancel, but in the lecture he said that 1 atm is also pretty close to 1 bar if you're wondering.

Rayna Irving 2C

One thing that helped me a lot was studying consistently throughout the quarter instead of cramming all the info in my head right before finals and midterms, because it helped me feel a lot less overwhelmed and stressed in the long run.

Rayna Irving 2C

For me, doing textbook problems, going to UA sessions when I'm not completely sure about a topic we went over, and watching chemistry review Youtube videos are the three things that I found help me the most when studying.

Rayna Irving 2C

I'm pretty sure we don't start using them unless we take the higher level chemistry classes in the future.

Rayna Irving 2C

I usually just search studying or reading music on Spotify (and it's most likely on other streaming services too) and a lot of good playlists come up that help me stay focused.

Rayna Irving 2C

I mainly try to use the textbook when I'm unsure about a certain topic in lecture, because it often goes into more detail and nuance. I also like to use it for practice problems as a kind of benchmark to see if I am retaining and comprehending the information.

Rayna Irving 2C

Definitely textbook problems and UA worksheets for specific topics have been the most useful for me.

Rayna Irving 2C

I would definitely keep your notes and save the outline to your computer with it worked out while you still remember the info so you can look back later.

Rayna Irving 2C

Thank you so much and good luck you and everyone else, as well!

Rayna Irving 2C

This month as definitely been overwhelming so far with trying to review for all my classes at once, but I'm pushing through and very excited for break!

Rayna Irving 2C

I watched this video too and it really helped me fill in the gaps of what I didn't understand about coordination compounds! Thanks for spreading the word

Rayna Irving 2C

I was wondering if there was any place that specifically lists all the polydentate ligands we have to memorize for the final as well as the number of bonding sites there are?

Rayna Irving 2C

Mainly, I'm going to try to review as many textbook problems as I can and try to re-read the textbook sections we went over so I can pick up any small details I may have forgotten. I also plan to go to as many review sessions as I can, especially for the fundamental part because it's been a couple w...

Rayna Irving 2C

Yeah I'm not sure what's happening either. I tried logging out and logging back in several times and it still isn't letting me watch it.

Rayna Irving 2C

Textbook practice problems help me the most with studying, but I would also go to as many step-up sessions and workshops as possible because they always give great examples that help a lot with the tests. As far as equations I would just stick with anything that looks familiar on our formula sheet w...

Rayna Irving 2C

I feel kinda okay about the material so far, but I just wish the tests weren't so high-stake where missing a few questions could drop you a whole letter grade. While this is true, I do really appreciate all of the resources he provides us to solidify our knowledge on the material.

Rayna Irving 2C

Yes, just remember that each single, double, triple, etc. bond still only count as one region of electron density and each lone pair also only counts as one region of electron density.

Rayna Irving 2C

I usually take a few breaths during the test and plan out how much time I have for each question so I don't feel so rushed. I also make sure I've done practice problems before and stop studying at least 10 minutes before the test so I have time to get everything together and calm down.

Rayna Irving 2C

I'm definitely going to try to look through the book again as well as redoing the practice problems because some questions always seem to pop up on the test. I also am going to try to go to as many step up and review sessions as I can so I can get a stronger understanding of the material. I would al...

Rayna Irving 2C

Since the last holiday we had a lecture, I'm assuming this time will be no different but I don't think we're still having discussions.

Rayna Irving 2C

Yes I'm pretty sure it is cumulative having all the material from midterm 1 and 2 plus whatever new things we learn by the end of the quarter.

Rayna Irving 2C

I usually like to take a nap if I don't have anymore classes at the time and binge watch my favorite shows that I needed to catch up on. I suggest taking time to do whatever hobby you like while you have free time to do so before more tests and homework problems are due.

Rayna Irving 2C

Is it correct to make the assumption that hybridization of orbitals only happens in covalent bonds and not ionic bonds because, with ionic bonds the atoms don't share electrons, they take them, but in covalent bonds they do share electrons?

Rayna Irving 2C

I was wondering how do we know that triple bonds have two pi bonds and one sigma bond, rather than two sigma bonds and one pi bond?

Rayna Irving 2C

In order to find out how many hydrogen bonding sites there are, you first count how many hydrogens there are bonded to F, O, or N atom, and then count the lone pairs on an F, O, N atom and that's it or are there any other steps to go through?

Rayna Irving 2C

I'm not sure whether this midterm will be harder or easier than the last one, but I know there will be more questions worth less points and the questions will be more conceptual rather than math-based since we didn't really do much math besides formal charges since the last test.

Rayna Irving 2C

No, I don't think we're expected to calculate bond length as of right now, just know certain trends and ideas like triple bonds are the shortest while single bonds are the longest, and the bigger atoms have longer bond lengths when bonded with another, etc.

Rayna Irving 2C

I don't really understand how you decide if a molecule has ample ___ bond character or overwhelmingly ___ bond character. I know you have to compare the lewis structures, the observed bond lengths and the expected values together but I don't really know what I'm looking for to choose the right answer.

Rayna Irving 2C

It was mentioned briefly in the Wednesday lecture last week, but I didn't really understand why a molecule with high polarizability and dispersion force strength will most likely be a solid, while a molecule with low polarizability and therefore lower dispersion force strength would most likely be a...

Rayna Irving 2C

Single bonds are longer than triple bonds because there is only one shared electron so the force that brings the atoms closer together is weaker than in a triple bond.

Rayna Irving 2C

Yes because you have to take into account the number of bonded electrons an atom has in order to calculate the formal charge.

Rayna Irving 2C

To be honest, this week hasn't been going that great because I'm trying to study for multiple midterms, attend as many office hours as I can, finish writing an essay as well as stay up to date with all the lectures, homework, and labs so it's a lot to juggle. Hopefully it will all be worth it though...

Rayna Irving 2C

I was just wondering If there was any particular reason why oxygen can be drawn with 7 electrons (6 lone electrons and one shared) instead of 6 when drawing the Lewis Structure for NO3- even though I thought oxygen can't break the octet rule without a d-orbital?

Rayna Irving 2C

I was worried about this too but I found out that if it isn't a metric unit, then we will be given the conversion factors to help us figure out the answer.

Rayna Irving 2C

I think the issue might be in the accuracy of your answer. I just plugged it in and got 12373 as an answer. maybe this answer would work? Thank you so much! I plugged this answer in and got it right. I think my calculator wasn't accurate enough and that was the issue but thanks again! Can someone h...

Rayna Irving 2C

I agree with everyone here in saying in order to not have a rounding error ruin my answer I usually keep my work and numbers in my calculator and then look for sig figs in the final answer as my last step.

Rayna Irving 2C

AliAsh 1H wrote:I think the issue might be in the accuracy of your answer. I just plugged it in and got 12373 as an answer. maybe this answer would work?

Thank you so much! I plugged this answer in and got it right. I think my calculator wasn't accurate enough and that was the issue but thanks again!

Rayna Irving 2C

Just checking, when a Sapling problem asks how many spectral lines there are when an electron returns to a lower level from n=7 for example, is the answer 6 because a line appears between the drop from 7 to 6, 6 to 5, 5 to 4, etc. all the way to 1?

Rayna Irving 2C

Thanks for asking this, I saw it too and I wasn't sure exactly what it meant so these answers are very helpful!

Rayna Irving 2C

I agree with what was said, if you end up with a fraction in your empirical formula, multiply it by whatever number gets the fraction to a whole number. Then don't forget to multiply all of your other numbers in the empirical formula by that same value to make sure everything is equal.

Rayna Irving 2C

I've been having trouble with the sapling problem: The electron in a hydrogen atom is excited to the n=7 shell and emits electromagnetic radiation when returning to lower energy levels. Determine the wavelength range in nanometers when returning to lower levels. I got the lower range of 93 nm (which...

Rayna Irving 2C

Yes, because it has a measurable mass, even if it seems really small, therefore the equation is applicable here.

Rayna Irving 2C

I usually make sure I can do all of the homework problems up until now because sometimes I forget some of the concepts that we went over in the beginning of the year, and I also go to step-up and workshop sessions to ask any questions I have and get more practice.

Rayna Irving 2C

My TA also said that they had a meeting with Dr. Lavelle and decided that graphing calculators wouldn't give students any advantage over non-graphing calculators since we are given an equation sheet already, so they ruled that any type of calculator is fine for this midterm.

Rayna Irving 2C

I agree with everyone above, from what we have learned so far, c is always a constant used in equations to represent the speed of light.

Rayna Irving 2C

If the Lyman Series is ever mentioned in a problem should we just assume E(final) is 1?

Rayna Irving 2C

I suggest reading over the textbook and going to step-up sessions and any other office hours that fit your schedule so you can be with other people who might come up with questions that you might not have thought about on your own to enhance your comprehension of the material.

Rayna Irving 2C

Usually, I use the same amount of sig figs in my answer as the number with the least amount in the problem. If the tests happen to be multiple choice, however, I don't know how much making an error in this process would affect our grade, but I would stick to this method just to be safe.

Rayna Irving 2C

I was wondering if there was a clear cut off of what wavelength is officially too small to be measured or should we just stick with the idea that anything smaller than around a picometer to 10^15 is too small, like discussed in the de Broglie module video?

Rayna Irving 2C

In general, when a question gives you the frequency in Hz of the light a hydrogen atom emits and the energy level the light reaches, how do you find what principle quantum level it started at? (Question #42 on this module)

Rayna Irving 2C

When considering significant figures in a number, is the (10^x) part also included when using scientific notation or does that part not count?

Rayna Irving 2C

I agree with all of the previous posts in saying that while it probably isn't required it does help me a lot to keep track of my work and make sure I'm not missing or confusing any units. At the very least I believe it can possibly open up the opportunity for partial credit even if your final answer...

Rayna Irving 2C

The way I usually do it is I copy exactly what is written on the periodic table when calculating molar mass and wait to deal with significant figures until I get my final answer for the problem. Usually what I've found is that any rounding errors are so small they're insignificant and don't really a...

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