CHEMISTRY COMMUNITY

Charlie Russell 2L

Thank you, Lavelle. Super fun two quarters!

Charlie Russell 2L

I agree that it may be important to memorize the trends covered in lecture and sapling.

Charlie Russell 2L

I think we are more likely to solve for k rather than ln(k). They are both similar.

Charlie Russell 2L

For future reference, look at the units you are using to see which ones you want to cancel to choose which R to use.

Charlie Russell 2L

Yeah, we definitely are!

Charlie Russell 2L

He went over a couple applications in one of the lectures. I briefly studied those.

Charlie Russell 2L

I think if both molarities are in mmol it's fine because the units cancel out in the Q ratio form

Charlie Russell 2L

I don't think he does

Charlie Russell 2L

Thank you, good luck to you too

Charlie Russell 2L

pre med gang yeet

Charlie Russell 2L

140 pts

Charlie Russell 2L

Yeah, Gibbs Free Energy! It's in Lecture 16, I believe!

Charlie Russell 2L

Probably only use the equations on the equations sheet because I don't think you will need anything off the eq sheet for the test!

Charlie Russell 2L

As Katie said! Also, if Q<K, reaction will continue to shift towards products, if Q>K, reaction will shift towards reactants.

Charlie Russell 2L

Does the direction of the particle matter? Does that count as another state?

Charlie Russell 2L

Also, qrev is just for reversible process with constant temperature!

Charlie Russell 2L

Q: What do chemists call a benzene ring with iron atoms replacing the carbon atoms?

A: A ferrous wheel.

Charlie Russell 2L

Oh good, this was a helpful reminder: I took AP Physics but for some reason forgot.

Charlie Russell 2L

Yeah, I think you can only use that equation when the process can be interpreted as reversible and at constant temperature.

Charlie Russell 2L

A photon checks into a hotel and is asked if he needs any help with his luggage. He says, "No, I'm traveling light."

Charlie Russell 2L

The real joke: my grade after this midterm.

Charlie Russell 2L

I think it just means to be able to use the Van't Hoff Eq that we talked about in Lecture 16!

There's the two different versions on the equation sheet!

Charlie Russell 2L

It's not a perfect isolated system since that doesn't exist in real life but it's pretty close! The long the heat stays in that mug, the closer to a perfect isolated system it is!

Charlie Russell 2L

hey guys just a reminder that if you're reading this, go treat yourself! we had our first midterm today and it wasn't the easiest, personally. so just a reminder to always keep going and never give up! and yes, it's okay to treat yourself after a very long and hard few weeks. yeah omg. preach. than...

Charlie Russell 2L

Ah, I'm scared to leave Lavelle's nest like I feel homeostatic right now with how I'm learning chem!

Charlie Russell 2L

:( there were definitely a few that I wish could've predicted would be on there and not had to overthink about but idk, I did everything I could so I'm hoping for the best for all of us. I just wanted that to feel like a breeze because I studied so much but eh. Anyways we live, we learn so hopefully...

Charlie Russell 2L

I mean, was that what I expected? No. But did we get through it? YES. I had felt like I prepared really well but then there were 3 really hard questions for me and I was just literally calculator scrambling (literally anything to get a correct answer that made some sorta sense - it was a lot of deep...

Charlie Russell 2L

Exactly! Thank you for this!!!

We really do have bumps but we will be better prepared for future classes!

The MCAT too!

We got this and we work really hard!

Charlie Russell 2L

Alvin Lai 3J wrote:In step 2, you need to do the -5000 kJ divided by -2878 kJ/mol, not the other way around. Everything else looks good, so try what I said instead.

Yes, I figured that out after playing with things! Thank you!

Charlie Russell 2L

In Module 2 Post-test Question 32: 2NO 2 (g) + 7H 2 (g) ---> 2NH 3 (g) + 4H 2 O (l) I thought because no other molecules are aqueous, that therefore H 2 O IS included in the K calculation because it isn't a solvent??? Can someone explain if/why I am wrong? None of the answers include H 2 O in the nu...

Charlie Russell 2L

Help, I'm having some trouble on this question :) Consider the combustion of butane gas C 4 H 10 (g) + O 2 (g) ---> CO 2 (g) + H 2 O (g) \delta H c = -2878 kJ/mol If 5000 kJ of heat is released, how many grams of oxygen were consumed? -----------------------------------------------------------------...

Charlie Russell 2L

(a) Well first write your balanced equation of the acid, HCl: HCl + H 2 O <-----> Cl - + H 3 O + Well all moles are at a 1:1 ratio with each other, this means you can use the given molarity of the desired HCl solution to find the pH: -log(H 3 O + ) (molarity of H 3 O + is the same!) (b) MOLARITY ini...

Charlie Russell 2L

I second this question, does anyone know?

Charlie Russell 2L

anything under K<10^3, it strongly favors reactants

anything above K>1, it strongly favors products

because K = [products]/[reactants]

Charlie Russell 2L

OMG THIS IS FANTASTIC! Thanks for sharing your application to chemistry!

p.s. Aliya and I are study buddies!

Charlie Russell 2L

I think kJ/mol is for standard reaction enthalpy of and enthalpy of formation!

Charlie Russell 2L

Summer_Corona 3L wrote:
Charlie Russell 2L wrote:Week 1 - 3!!

I'm scared! Is anyone else scared?

I'm definitely nervous and ready to just get it over with lol.

No same tho!

I paid my tuition a day after the deadline and got kicked outta all my classes last week :( I finally just got caught up with Chemistry!

Charlie Russell 2L

Week 1 - 3!! I'm scared! Is anyone else scared? I definitely feel nervous for the midterm but I would recommend going to UA sessions especially if you’ve finished all the textbook practice questions! I feel that the worksheets and practice problems they have are really helpful in prepping for exams...

Charlie Russell 2L

I think it just falls under ICE Charts and Equilibria stuff.

14A was a different story but for 14B, that's all we should have to know tg!!!

Charlie Russell 2L

No picture of work, I don't believe. He has offered partial credit in the past for choosing answers that were wrong but closer than blatantly wrong, though. But as for showing work, that is not a part of his midterms or exams! Oh, and one more thing! Lavelle doesn't offer any extra credit in his co...

Charlie Russell 2L

No picture of work, I don't believe.

He has offered partial credit in the past for choosing answers that were wrong but closer than blatantly wrong, though.

But as for showing work, that is not a part of his midterms or exams!

Charlie Russell 2L

I'm pretty sure they are run by different UAs so therefore, they are different. I would just try to find a UA that is good and works well with your studying so you can get the most out of it! I think it may be a but redundant to go to multiple a week. I find much more help in self-study once I feel ...

Charlie Russell 2L

Olivia Yang 3J wrote:Lavelle also said that the relevant week 3 problems in the textbook are 4D.15, 4D.17, 4D.19, 4D.21, 4D.23, 4E.5, 4E.7, 4E.9, 4.29, and 4.31

Oh wow, thank you!!!

This helps a ton for prep!

Charlie Russell 2L

I don't think there is...

Older year students may have old exams but I'm not positive if that's against the rules or anything!

Charlie Russell 2L

Marry me?

Like, literally thank you so much!!!!

Charlie Russell 2L

Oh wow! Very interesting to see you put Chem to action and apply it to real world stuff!

I suck at cooking but maybe once I get a little further in Chem, I'll be the next Gordon Ramsey???

Charlie Russell 2L

GUYS!!! I'M LATE BUT LISTEN TO THE MISEDUCATION OF LAURYN HILL ALBUM!!!!

IT'S ON ANOTHER LEVEL OF ARTISTRY!

Charlie Russell 2L

Steam stays 100 degrees as it turns back into a liquid whereas water immediately decreases in temperature.

If you look at the picture of the curve it may make more sense!

Charlie Russell 2L

TEXTBOOK PROBLEMS ALL THE WAY!

Me and my study buddy for the class do them each week to review materials!

We save the harder end of unit textbook questions for before the final!

Do your sapling! Communicate on Chem Comm! And go to those step up sessions if you need more help!

Charlie Russell 2L

You're gonna wanna learn them all in case a problem gives you given that only support that one method!

3rd method is most accurate, 2nd method is least accurate!

Charlie Russell 2L

Yeah, I think it means that the other atoms in a molecule can have an effect on one bond's enthalpy.

And so, they take the average of all the different varying enthalpies!

Charlie Russell 2L

Week 1 - 3!!

I'm scared! Is anyone else scared?

Charlie Russell 2L

To be safe, only consider the X to be super small if the K value is less than 10^-4!!!

Hope this helps!

Charlie Russell 2L

Hey guys,

Can someone help me understand Standard Reaction Enthalpy?

What does it mean, tell us? What's its purpose?

Hopefully you can explain in more simple terms because the lecture tripped me up a little.

Thank you!

Charlie Russell 2L

Sorry for the late response but I figured I would answer, regardless:

Yes, you are correct the the same logic does apply and the triple will have, in total 5 "points of contact."

Charlie Russell 2L

Chem_Mod wrote:They are present in large excess compared to reactant concentration.
I'll review this again in Wednesday's class.

Okay yes, I now understand after last Wednesday's lecture, thank you!

Charlie Russell 2L

Probably not, I'm curious though that Dr. Lavelle might consider making his prerecorded lectures the modules for next year.

I think that would be smart since pre-recorded lectures/modules certainly have their benefits!

Charlie Russell 2L

No, I think it will actually be during Friday lecture time of I am not mistaken.

Charlie Russell 2L

Since everyone has the required calculator which would have that program on it, I would say it is fine but that's a good question for Lavelle!

Charlie Russell 2L

You have forgotten to balance your equation: 2OH!!!

Charlie Russell 2L

Yes, I believe you are correct in saying that in the reactants, their total pressure does not change because, as mentioned, the partial pressures of the reactants have a direct relationship with each other, and an inverse relationship with the product partial pressures!

Charlie Russell 2L

1. To determine K c : K c = each concentration of product divided by each concentration of reactant ***remember put these values to the power of their stoichiometric coefficients*** Example: 2H 2 O <---> OH - + H 3 O + K c = [OH - ][H 3 O + ] / [H 2 O] 2 Just plug n chug to get K c ! 2. Q is the val...

Charlie Russell 2L

Wait... so why do pure liquids experience basically no change in concentration during a chemical reaction? I understand that pure solids do not have the "liter" aspect of molarity = mol/L thus a "solid concentration" does not exist but I am getting tripped up by the concepts surr...

Charlie Russell 2L

The single bonded oxygen atoms can make a coordinate covalent bond to another transition metal. It would make their formal charge zero if they did, as well, thus making this bidentate because of those two single bond atoms.

Charlie Russell 2L

AHHH LOVE THIS! We all got this, we have to finish strong. Thank you for the reminder! Everybody remember to eat, sleep, stay hydrated and just take care of yourself (I know we can all get caught up studying and grinding during week 10 and finals week.) Good luck to everybody. So true, Meredith! Ev...

Charlie Russell 2L

Just a quick reminder that Lavelle would like us to do the class evaluations ! You can find them in an email sent to your school Gmail account. Also, make sure to take advantage of the review sessions this week: - The review schedules can be found in your school email, in several messages from Lavel...

Charlie Russell 2L

Pi-bonds have 2 areas of contact (the 2 p orbitals line up side to side!). Think of a ladder. If you try to move 1 ring but not the other, the ladder (bond) will break. For sigma bonds, they have 1 point of contact (end to end), think about wringing out a towel (lol), you can twist either way withou...

Charlie Russell 2L

I've heard TA's talking about Lavelle considering making the exam more difficult because the grades were too high (dear [censored], I hope that's a rumor or scare tactic to make us study and not reality). I've heard nothing about extra credit but I'm sure he knows everyone would deeply appreciate it...

Charlie Russell 2L

The two p-orbitals overlap. Think of a LADDER. You cannot move 1 ring of the ladder without moving the other unless you break it (the bond breaks).

Charlie Russell 2L

Any "lewis base" that is directly bound to a transition metal is what I consider to be a ligand.

Charlie Russell 2L

I hope Lavelle offers some EC, it would give me a little room to breathe for this final as every single question counts! So nervous!

Also, some instructors, in fact, HAVE offered extra credit for the evaluations. They're anonymous BUT I think professors can see who completed them.

Charlie Russell 2L

Oh dang, this is good to know!

I'm excited and scared for 14B tbh!!!

Charlie Russell 2L

Go to Lavelle's review sessions this week, he sent them in an email and they are flexible timing. Also, I would study the older material first, theoretically, if you did well on midterm two then you shouldn't have to worry about that as much! Whatever you feel weakest in, that's what you study. Take...

Charlie Russell 2L

Me too! I thought it was my wifi or something so I'm happy to know I'm not alone!

Charlie Russell 2L

The one in the textbook is useful, as well.

Charlie Russell 2L

The photoelectric effect proved that light can act as particles! This was really a revolutionizing discovery about light. So just also know that this experiment contributes to the particle part of the wave-particle duality of light!

Charlie Russell 2L

The given number (in the question) with the LEAST significant figures is the number of significant figures that you use in your answer. This applies to any sort of question.

The second example you gave should have 2 sig figs for this reason.

Charlie Russell 2L

Marco Vivar 3G wrote:My favorite tv show to watch on Netflix is Avatar The Last Airbender. I know this show is popular but it has so much rewatchability!

YES! ngl this show slappppppssssss!!!

Charlie Russell 2L

Killing Eve is very, very good. I highly recommend that one!

Also, Game of Thrones (I started watching but then school started so I had to stop) is also very good.

Rick and Morty omfg, so funny imo.

These are all great shows, I promise you will enjoy!

Charlie Russell 2L

You just gotta Quizlet those out, I think that's the best way and it took me maybe 5 minutes/day for two days until I had them down.

Charlie Russell 2L

Another thing to remember is that elements right next to each other will have closer electronegativity than those directly below elements. So two elements touching in different periods will have greater electronegativity than that element touching one of the same period.

Charlie Russell 2L

Yes, both viscosity and surface tension directly relate to increasing intermolecular forces.

Charlie Russell 2L

Could someone interpret this statement from 1E.5 in the textbook: "Electrons in an s-orbital are more effective than those in other orbitals at shielding other electrons from the nuclear charge because an electron in an s-orbital can penetrate to the nucleus of the atom." I understand that...

Charlie Russell 2L

No, not interchangeable terms. Lewis acids and bases are when one atom or compound (a Lewis base) can donate to another atom or compound (Lewis acid). Cations and anions when bonded are electrostatically attracted enough for an electron to get transferred over in an ionic bond (ion-ion bond).

Charlie Russell 2L

Hey, I just answered a question similar to this one! Here was my answer: Oxidation numbers, also called oxidation states, are the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom. An oxidation number can be assigned to a given element or...

Charlie Russell 2L

Because the difference in electronegativity between H and the electronegative atom (N, O, F) must be strong enough to keep them together, I am assuming. So before the bond, the H has a high positive delta (because if is covalently bonded to a strongly electronegative atom N, O, F) and this H can for...

Charlie Russell 2L

Oxidation numbers, also called oxidation states, are the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom. An oxidation number can be assigned to a given element or compound by following the following rules: - The oxidation number of a f...

Charlie Russell 2L

He's right, there are 8. In addition to what he explained, I would simply offer the advice to draw out both structures next to each other and keep in mind the H-Bond rules, it should make it a lot more intuitive and easier!

Charlie Russell 2L

I have found the answer to be A, B, and E. I understand I2 but I don't understand C2H6 or BF3. How do C and H not have a difference in electronegativity and why would BF3 and NF3 have similar forces applied to them? They both have different electronegativity between the atoms in their molecules and...

Charlie Russell 2L

For Lewis Structures, we TYPICALLY try to get as many formal charges to 0 as possible, as this is the most stable, so if a double bond allows most of the atoms to have a formal charge of zero, we will "exchange" a lone pair for a double bond. But be careful for atoms like F- (fluorine) bec...

Charlie Russell 2L

Coulomb's Law shows that like charges repel and opposite charges attract. If F in the Coulomb's Law Equation is negative, then the charges are attracting and vice versa.

Charlie Russell 2L

Because a compound can be made up of covalently bonded molecules the bind, ionically, to eachother.

Charlie Russell 2L

Will the Midterm scores be posted under "Grades" on CCLE?

Charlie Russell 2L

I like everything music: listening, singing, even making music in my head can be fun. Studying con be relaxing too if you're not studying or cramming under a deadline!

Charlie Russell 2L

ħ is not h/4pi!!! It is h/2pi. 4pi was only in the equation used for the midterm because there was a 2 in the denominator to multiply!

Charlie Russell 2L

In our workshop, the TA said that the midterm was technically supposed to get graded after the last discussion section takes it on Friday, but he also told us to not be surprised if it takes a little longer!

Charlie Russell 2L

Since m is the SI unit, ALWAYS convert to the SI unit unless the problem asks for a different unit.

Charlie Russell 2L

What did the thermometer say to the measuring cylinder?
“You may be graduated, but I have several degrees.”

Charlie Russell 2L

Could you clarify the question?

You can use a spectrometer to find wavelengths of spectra, the spectra would detail wavelengths it could pick up, presumably.

Charlie Russell 2L

You'll be okay, its only one class! And think of how stressful this whole year has been!

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