CHEMISTRY COMMUNITY

Kayko Lee 1C

ʅʕ•ᴥ•ʔʃ boost

Kayko Lee 1C

Angelica Soriano 3L wrote:My favorite song at the moment is an anime opening but it's so good!!
Shogeki - Yuko Ando
https://open.spotify.com/track/5QwAdWCn ... zzNnCQbYsg

yessssss the ending for this season for aot is so amazing easily one of my favorite anime op/eds

Kayko Lee 1C

Is there anything about not including liquids and solids in rate laws? Thanks!

Kayko Lee 1C

E naught will be 0 when the cathode is the same metal as the anode. For example, if we were talking about Au and the oxidation was the same state for both the cathode and anode then E naught would be equal to 0

Kayko Lee 1C

As said that you might have to match graphs I would make sure how the reactions look with and without the natural log and for the different orders

Kayko Lee 1C

So since it's not possible for us to automatically know the E o of HF we can calculate that value using the E o of fluorine from the appendix and the given E o for the whole reaction. So, the way we can start this off is +3.03V=2.87-E o . Here, we get that the unknown value is -.16V, which is the st...

Kayko Lee 1C

For 6.57 from the hw problems why do we square root the value K? I just want to confirm if my thought is correct that we have to square root K because it is K_a*K_b and the question is just asking for K_a since I got rusty on acids/bases

Kayko Lee 1C

For part d in 6N.3 why is .55 being multiplied with .277 in the numberator in the solutions manual? I instead multiplied .55 with .867 in the denominator because of products over reactants (anode/cathode) as I thought .55 was part of the reactants and I checked the page that lists which problems hav...

Kayko Lee 1C

When finding the half-reactions without a given cell diagram how do we know which reaction should be reversed when both equations have their electrons added on the same side?

Kayko Lee 1C

Could someone explain the relationship between positive/negative standard cell potentials, K, and reduction of H ions? I read that when the standard cell potential of a redox couple<0 then K<1, and that would cause hydrogen ions to be reduced. However I read a later statement that said "K>1 for...

Kayko Lee 1C

For Sapling problems where can I find the table for different potential differences? Like for section 6L values aren't given for voltages

Kayko Lee 1C

In the self test portion 6L.2A for Sapling where did the H₂⁺(g) come from? I was able to get the rest except for that portion in the problem. Thank you!

Kayko Lee 1C

For finding the number of moles in the equation used to find the gibbs free energy I'm not super sure where it comes from so do the number of moles come from how many electrons are added to both the redox equations? From the problems that I've done so far the number of electrons added to both half r...

Kayko Lee 1C

As for balancing charges in redox equations I had to relearn oxidation numbers in case this is what you need so for example: MnO 4 - you want to know that O has a oxidation number of -2 and there are 4 Os. Therefore to find the oxidation number of Mn since it isn't clear as it's a transition metal y...

Kayko Lee 1C

When I crave something spicy as a snack I definitely love eating tteokbokki! It's a korean dish made of rice cakes and fish cakes with spicy pepper sauce

Kayko Lee 1C

When a problem says that compression occurs on a system I think of the work as positive as the surroundings are doing work on the system. So, when expansion occurs work would be negative since it's the system this time doing the work by expanding.

Kayko Lee 1C

In this question the book asks for the entropy of the whole process of water heating up, turning into vapor, and the water vapor cooling down to the 85 degrees. Realistically the process of the problem doesn't make sense since going below 100 degrees C would be liquid water instead of water vapor bu...

Kayko Lee 1C

I destressed by catching up with shows like AOT and jujutsu kaisen last night n decided to sleep in until like 2 in the afternoon today :>

Kayko Lee 1C

If you're into action/thriller anime I definitely recommend Parasyte on Netflix

Kayko Lee 1C

Would calculating the irreversible work done by a gas vs an ideal isothermal gas be done differently? For example in Matthew's workshop (Q1 Week 6) a question asked to find the work done of an ideal gas in the isothermal reversible process while the initial pressure and volume and final volume was g...

Kayko Lee 1C

In reference to the solutions manual for 4I.5 where did 75.3 J/K*mol come from towards the last couple lines of the calculation? I believe that's the C_p,m value of the temperature change equation of entropy but I'm unable to derive that exact value. Thanks!

Kayko Lee 1C

Can a nonspontaneous process with a negative ΔS become spontaneous if the temperature is increased (assuming that ΔH and ΔS are both independent of temperature)? answer: no
I'm having trouble understanding this question so could someone break it down on what it means? Thanks!

Kayko Lee 1C

When calculating the entropy change of surroundings I'm not sure when the equation should be negative. What are some of the conditions in order for the equation to be negative so that the resulting entropy change in surroundings is negative?

Kayko Lee 1C

For #1 in 4I in the solutions manual why is 40000J positive in one of the calculations? Is it because the reservoir at 200K is gaining the 4000J that it is positive and the reservoir at 800K is having its heat energy transferred away therefore the 40000J is negative? Thanks!

Kayko Lee 1C

You have just discovered two mysterious gases: purple gas (PG) and brown gas (BG). They react to somehow produce water vapor and carbon dioxide via the reaction below. 2 PG(g) + BG(g) → 4 CO2(g) + H2O(g) ΔH = -245 kJ Determine the change in internal energy when 1.00 mol of CO2 is produced by the abo...

Kayko Lee 1C

Could someone explain how temperature change occurs with irreversible reactions? Thanks!

Kayko Lee 1C

I definitely recommend The Book Thief if you haven't read it yet! It centers on people during the holocaust and the writing depicts their narratives really well and it's one of the few books I wouldn't mind rereading anytime

Kayko Lee 1C

Before finals/midterms UA Justin holds a review session since his step-up and workshop are back to back so he just combines the hours

Kayko Lee 1C

Q: Calculate the standard entropy of vaporization of argon at its normal boiling point ΔH vap /(kJ*mol -1 ) for argon=6.5 and boiling point of argon is T b /K is 87.3; answer: 74 J/(K*mol) I used the equation of the stand entropy of vaporization to find the vaporization of argon and divided 87.3 fro...

Kayko Lee 1C

A sample of benzene, C 6 H 6 was brought to 80°C, its normal boiling point. The heating was continued until an additional 15.4 kJ had been supplied, resulting in 39.1 g of boiling benzene becoming vaporized. What is the enthalpy of vaporization of benzene at its boiling point? Answer: 30.8 kJ/mol Us...

Kayko Lee 1C

From last quarter's experience and from this one so far I don't think it's necessary to memorize those definitions since conceptual topics he talks about are definitely discussed at least for a little bit during lectures so I wouldn't worry about it in my opinion since he didn't mention it at all

Kayko Lee 1C

Self-test 4C.1A In an exothermic reaction at constant pressure, 50. kJ of energy left the system as heat and 20. kJ of energy left the system as expansion work. What are the values of (a) ΔH and (b) ΔU for this process? Answers: -50 kJ; -70 kJ My question is why would only the 50 kJ be accounted for...

Kayko Lee 1C

I'm having trouble understanding why the calculations were arranged as it was by looking at the manual for 4A.9. Specifically, I'm not sure why 100 degrees C was subtracted from the final temperature for copper and 22 subtracted from the final temperature of water. If anyone could explain the concep...

Kayko Lee 1C

Personally I'm going to try to take it next quarter since I've heard it's easier online and especially because I think taking 14b and then lab back-to-back would be easier than waiting for a long period of time because I'm definitely going to forget a lot of what I learned this quarter if it's going...

Kayko Lee 1C

Lorena_Morales_1K wrote:Why is bond formation exothermic again?

I believe it's exothermic because the system loses energy to form the bonds and since there's a decrease in energy, the energy is lost as heat and makes the process exothermic

Kayko Lee 1C

Quinton Sprague 1A wrote:Any ideas when we should know our grades? Shouldn't expect any curve right?

Sadly I'd say to not expect a curve on exams for this class but from what happened last quarter we can maybe expect grades to be out around the end of next week since it took about a week for grades to return in 14a

Kayko Lee 1C

Once I catch up with my other classes the past week I definitely plan on going outside for a little bit and practice skating or drive for a little bit! Being cooped up in the house studying for the midterm was really draining so getting fresh air is always a good thing

Kayko Lee 1C

For 6C.9 in Sapling I got the same exact pOHs that the solutions manual gave out and the question was to order the bases in increasing strength. The way I did it was 4.75<8.75<9.25<10.55 since I thought that the higher the number meant a stronger pOH. The answer however put the arrows in the opposit...

Kayko Lee 1C

I was working through the example in 4E.3 for reference and my question is how would we know which bonds have to be broken in a substance, such as CH 3 CHBrCH 2 Br if the question doesn't tell us which ones? Also how necessary would drawing lewis structures in these type of problems be since Lavelle...

Kayko Lee 1C

I really love R&B, alternative R&B and I'm also getting into K R&B so if anyone has recommendations pass them over lol. Some of the artists I love are SZA, Kehlani, Brockhampton, Tyler, DEAN, GOT7, Joji, and the list of course goes on. I'm excited to see other people's music tastes than...

Kayko Lee 1C

For example if the pH was 4, you would do 10^-4 to find the concentration!

Kayko Lee 1C

I was working through a self test that Sapling gave right after 4D.6 and I have no clue on how to write the reaction formula so therefore I can't reach the solution since I'm not sure what chemicals will be produced in order to look up their values for their enthalpies of formation. Do we have to kn...

Kayko Lee 1C

For parts a and b could someone explain the answers? After reading the solutions from the manual I'm still confused on the problem as I don't have a starting point on understanding it. Thanks for any help!

Kayko Lee 1C

Right above exercise one theres 2 links that lead to the equilibrium constants! I'm sure we don't have to memorize these values since that's really extensive

Kayko Lee 1C

For questions 15, 17, and 19 in 6D how would we able to calculate pH? I wasn't able to find the equilibrium concentrations of those acids/bases on the tables it told us to refer to and I'm assuming we shouldn't have to google the concentrations, so are these chemicals conjugate acids/bases? For 6D.1...

Kayko Lee 1C

At a certain temperature, the given reaction has an equilibrium constant of Kp=391 . PCl3(g)+Cl2(g)↽−−⇀PCl5(g) PCl5 is placed in a sealed container at an initial pressure of 0.0640 bar . What is the total pressure at equilibrium? Im having trouble getting the correct answer for this problem. I set ...

Kayko Lee 1C

Calculate the molar concentration of OH - in solutions with the following molar concentration of H 3 O + : c) 3.1 mol/L I was able to get to get the other parts correct as I just divided what was given from 1x10 -14 but I ended up getting 3.2x10 -15 as my answer but the solution manual says 3.2 x 10...

Kayko Lee 1C

Given that K = 6 x 10 3 , calculate the amount (in moles) of NO that must be added to a 1 L vessel containing .245 mol SO 3 to form .24 mol SO 2 at equilibrium. SO 3 (g)+NO(g) -> SO 2 (g)+NO 2 (g) I got confused on how to solve this problem and after looking at the solution manual why would we subtr...

Kayko Lee 1C

The way I discerned the two was whether the question asked for equilibrium or equilibrium *composition* so then I would look at K_c but correct me if I'm wrong on my reasoning

Kayko Lee 1C

Since the images are showing the states of equilibrium, only temperature can change the equilibrium concentration. Therefore, only a) would be the correct answer. For b), I believe it doesn't matter whether you add or remove atoms from a concentration, the equilibrium constant will be the same after...

Kayko Lee 1C

For part d) in 5J.5: State whether reactants or products will be favored by an increase in the total pressure (resulting from compression) or if there is no change on the equilibria. 2HD(g) + H 2 (g) ⇌ D 2 (g) Originally my answer was that the products would be favored because there is 1 mole compar...

Kayko Lee 1C

If you like animated films a popular one is A Silent Voice and personally I really like In This Corner of the World as it covers darker topics really well

Kayko Lee 1C

How do we find which one of two molecules is thermodynamically more stable relative to its atoms? For reference this comes from part c) in 5I.13 and I'm not sure what the specific statements are on how to find out which molecule is more stable in comparison to another one referring to equilibrium. T...

Kayko Lee 1C

I was doing the sample problems that Sapling works out and what does "<<" mean? For example, "make the approximation that x << 3.21 and 6.21, then solve the equilibrium expression for x."

Kayko Lee 1C

a) they switched the placements of the reactants/products so you would just take the inverse of K, so K in this problem would be 1/41 b) the given equation is the given equation in the problem but the coefficients are just divided by 2 so you would take the square root of 41 as your answer (~6.4). N...

Kayko Lee 1C

For #5 on the Sapling hw and 5H.3 in the textbook for reference, how would you add various chemical equations together to eventually reach a new one of those combinations? I'm assuming this is a fundamental skill that I have to brush up on so I'd appreciate any help!

Kayko Lee 1C

From what I understand about the topic for now is that even though solids aren't included in the expression for finding the equilibrium I think it could increase the amount of product being formed if the equation given isn't balanced since even though solids/liquids aren't included in finding equili...

Kayko Lee 1C

Like what people have said the UA sessions are extremely helpful and although Lavelle calls it an extra resource I kind of see it as necessary sometimes because some UAs are really good about going over problems you'd never expect to see Lavelle throw at you but possibly could since many of the prob...

Kayko Lee 1C

I'm definitely going to be sleeping a lot and I'm going to plan on being outside of my house a lot more, like my backyard or whatnot, since I've needed all the time I have to study for finals and haven't gotten fresh air much ;/

Kayko Lee 1C

Personally I find it relaxing when I talk to my close friends! So whenever I take breaks I talk with them because it offers a temporary relief from anxieties and it also helps me not spiral into only thinking about myself and what I can do/ can't do and being in the company of others keeps my perspe...

Kayko Lee 1C

I tried pavloving myself to this one soundtrack (I forgot the name but it was an instrumental that was looped for an hour) so that I could be 100% focused during the hour because I work suuuuper slow and adding distractions too and it kind of worked o.o

Kayko Lee 1C

I'm going to be painting my board once I get the materials and plan it and hopefully and I can finish it over break! Besides that I'm literally gonna snooze

Kayko Lee 1C

By any chance has Katherine posted her slides on chem comm when she went over acids and bases? I'm trying to look for it but so far I haven't been able to find it and in case she hasn't I'd really appreciate it anyone doesn't mind sending their notes from the session!

Kayko Lee 1C

Decide whether an aqueous solution of each of the following salts has a pH equal to, greater than, or less than 7: KF F - + H 2 O -> HF + OH - (greater than 7) How do we know that it's specifically potassium that's left out of the equation? I got confused as fluorine also has a single charge but as ...

Kayko Lee 1C

Write the chemical equations for the proton transfer equilibria of the following acids in aqueous solution and identify the conjugate acid–base pairs in each case: C 6 H 5 NH 3 + when this reacted with water the compound lost a proton to become -NH 2 at the end along with H 3 O + as a product. I tho...

Kayko Lee 1C

I'm still struggling with understanding acids/bases so for neutralization reactions would water only be a product if the reactants are a strong acid and strong base? I was doing the textbook problems and I didn't see H2O come up as a product as there weren't any strong acids as reactants in the form...

Kayko Lee 1C

I think that they pretty much mean the same thing as they both have the same roles, so I believe that we were just introduced to the term ligand when we specifically dove into the topic of coordination complexes and ligands would be a more appropriate term than lewis bases somehow

Kayko Lee 1C

I believe that they are generally the same thing and you can use either name to refer to something but a lewis acid would be anything that accepts electron pairs and a bronsted acid would be something that is a proton acceptor. For example BF3 would be a lewis acid because it doesn't have any electr...

Kayko Lee 1C

I just want to confirm that if for example you had to find the molecular geometry for I3- it would be linear because they're all iodines? I got 3 lone pairs for that and thought it would be bent but it was linear instead

Kayko Lee 1C

I was reviewing past textbook problems and a question was: How many orbitals can have the following quantum numbers in an atom for n=2? and I said 5 but the solution is apparently 4. Why would it be 4?

Kayko Lee 1C

question: Select an acid and a base for a neutralization reaction that results in the formation of zinc nitrite answer: Zn(OH)2+2HNO2 -> Zn(NO2)2+2H2O I was able to get the basic skeleton of this down but I wasn't able to get the full answer because I wasn't sure on how to do the subscripts. This wa...

Kayko Lee 1C

That's right! and if there's 3 regions of electron density it would be sp2 as such

Kayko Lee 1C

Correct me if I'm wrong ofc but I think those are different topics? Because for resonance structures I don't think there's necessarily a coordination number as they're just marked with the sum of the formal charges of the atoms but I believe that for coordination compounds the coordination number wo...

Kayko Lee 1C

For the electron configurations I just keep an eye out if the transition metal in the configuration has 4 or 9 electrons because then you def want to fill it to 5 or 10 electrons by taking away an electron from the s orbital and adding it to the d orbital. As for orbital diagrams it helps when I vis...

Kayko Lee 1C

c) determine the coordination number of the metal ion in each of the following complexes: [PtCl2(en)2]2+
solution: 6 (en is bidentate)
I just want to confirm that the solution is 6 because its 2 bidentates (4) + 2 chlorines? (2)(2)+2=6?

Kayko Lee 1C

Question: If the ligand can be polydentate, give the maximum number of places on the ligand that can bind simultaneously to a single metal center (CO3(2-), carbonate) b) answer: CO3(2-) can bind to a metal through either 1 or 2 oxygen atoms. Therefore, it can be a mono or bidentate ligand. Could som...

Kayko Lee 1C

For part a in the textbook for 9C.3 how were there 3 potassiums in the solution: K3[Cr(CN)6]? The question is to write the formula for potassium hexacyanidochromate(III). Thanks for any help!

Kayko Lee 1C

Yeaaa this seems really iffy I would ask a TA or a UA about this question because I've seen multiple typos in the textbook and sometimes they don't always explain the answers in the manual if this question is one of those cases

Kayko Lee 1C

I remember people saying that sometimes, it really depends, that Lavelle can give points back or such at the end depending on the majority of student performance I believe. I wouldn't count on it too much tho ToT

Kayko Lee 1C

I remember that Lavelle said to expect problems from the textbook on the midterm and for midterm one there was definitely a question from the book and that was one of the few that I didn't do so I'm sure that I missed that one haha :( but def go through all the textbook problems to familiarize yours...

Kayko Lee 1C

I would go to UA or workshop sessions as much as possible! The UAs can be really helpful for refreshers and people who create their workshop sheets sometimes pull old test problems from other years as practice problems.

Kayko Lee 1C

I just read about it in the textbook and I don't believe there is? Since they depend on the number of bonds that form I wouldn't say that there's a trend or a significantly noticeable one in my opinion.

Kayko Lee 1C

My all time favorite show is Bobs Burgers, it's animated but also witty. I also have recently gotten into Naruto. I know that sounds kinda whack but surprisingly its really good, and has an insane amount of episodes to you'll always have another episode to watch. I actually just spent almost 11 hou...

Kayko Lee 1C

I would call out green -_-

Kayko Lee 1C

Wait never mind it said to omit this part of the problem my bad

Kayko Lee 1C

The question says to find the element with the ground state configuration [Rn](7s^2)(6d^2) and it says that it is thorium. How would this be so since there isn't an f block mentioned in the question? I found a previous post on this but it didn't help too much and a ta said it wouldn't be something t...

Kayko Lee 1C

So just to clarify 3d^5 and even 3d^10 will always have a lower energy than 4s^2?

Kayko Lee 1C

On the 2nd part of the question for #9 "Which of the lewis structures of the perchlorate ion are most plausible based on the experimental data" I got it incorrect but on the feedback it told me how to find the average bond length ClO4-. Is that relevant to answering the question? If so how...

Kayko Lee 1C

This new show on crunchyroll started releasing episodes somewhat recently and it's called jujutsu kaisen! If you like action anime it has a lot of potential since it just started and it gained a lot of attention already and I think that it's worth the hype so far. I also just finished this one calle...

Kayko Lee 1C

I'd go ahead and follow green

Kayko Lee 1C

I'd say the bookwork problems are the most relevant so far to the tests that Lavelle gives but the worksheets that the UA provides have been really helpful too and I use them to solidy my understanding or as a means of finding out what I need to study more

Kayko Lee 1C

For Ga on this problem I got [Ar] (4s^2)(3d^10)(4p^1) but the answer in the book for this problem has the 3d and 4s switched to [Ar](3d^10)(4s^2)(4p^1). I followed the Aufbau principle so I just wanted to make sure if I missed anything while doing this problem since sometimes there are typos in the ...

Kayko Lee 1C

How do I find the number of valence electrons for the d-block? (especially for elements in higher periods) I still get confused about this and thanks for any help!

Kayko Lee 1C

I would use de Broglie's for this problem but only for the electron part because an electron has mass but a photon doesn't have mass. For the photon one, your first step would be to convert 2.2 μm into m since planck's constant had meters in it. So, after converting into m you would find the frequen...

Kayko Lee 1C

Just like what was said I would use rhydberg's equation to find the number of spectral lines. From the equation, it solves for v and then you would have to solve for wavelength after that. As for the final energy levels, I think of it as what is the largest range that nfinal could be, and nfinal can...

Kayko Lee 1C

The average speed of a diatomic chlorine molecule at 25 ∘C is 323.9 m⋅s−1 . What is the average wavelength of a chlorine molecule at this temperature? Assume that the molecule acts as a single particle. On the feedback that I get after getting it wrong it says to convert the molar mass of a diatomic...

Kayko Lee 1C

For the f-block why do we go up to 14 instead of 15?

Kayko Lee 1C

So in the first part of the problem, it mentions velocity so you can use that information to find the kinetic energy. You'd also need the mass of an election as well, so Ke = (1/2)(mass of an electron)(velocity)^2. Also, you are given the work function. Therefore, you can use the equation E = Ek (ki...

Kayko Lee 1C

"How many orbitals can have the following quantum numbers in an atom: n=2" I still get a little confused on this topic sometimes and the answer for this was 4 orbitals. How would it be 4 orbitals? This is part c from 1D.23 on sapling

Kayko Lee 1C

For me, I just memorized the specific numbers that go into the lyman and balmer series but I suppose a way you can think of it is that for the lymann series it can fall to a lower level, n =1, than the balmer series, n=2. So, I just correlated the lyman series being able to reach a lower level to ha...

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