CHEMISTRY COMMUNITY

Sana Nagori 2H

I think I'll just skim over textbook chapters which is what I've done for the midterms and it seems to have worked so far (in addition to practice problems)

Sana Nagori 2H

I don't think you're supposed to ever have intermediates in the overall rate law. If the slow step ends up having one we usually do the pre-equilibrium method to get rid of it. I don't know what the case would be if we explicitly know the previous steps isn't fast at equilibrium. Also, the UAs have ...

Sana Nagori 2H

others have explained it in detail but yeah you need to do the pre-equilibrium method

Sana Nagori 2H

They both give the same answer!

Sana Nagori 2H

I don't think temperature changes activation energy, it just increases the rate.

Sana Nagori 2H

It helps to draw the diagram out. This is an exothermic reaction which you know from the enthalpy so you'll draw the diagram going from high to low. The difference between the products and reactants is a magnitude of 49. So this is from one end to another. However, the middle has a little hump you n...

Sana Nagori 2H

Yes this structure has resonance (I think it is benzene). So instead of forming 3 double and 3 single bonds you're actually forming 6 mixed bonds. This is assuming you're breaking all the bonds first and then reforming everything again (which is the method I prefer)

Sana Nagori 2H

Yeah I've been struggling with them too. I think I'll just try to watch some videos and do practice problems to get the hang of it.

Sana Nagori 2H

I think it was just to understand since we spend most of our time doing calculations but it might be helpful for conceptual type questions

Sana Nagori 2H

Just realizing that I'm trying my best and that one grade during such a difficult doesn't define me! We'll get through this, we're almost done! Take some breaks, remember to eat and sleep, take some walks and watch tv when it gets too overwhelming. You got this :))

Sana Nagori 2H

glad you guys were able to put this event on!

Sana Nagori 2H

no new ones have been added as far as I know

Sana Nagori 2H

I am currently not dealing with it LMAO

Sana Nagori 2H

I think you use Nernst equation. So you need to find the Enaught and then plug everything in to the equation. For Q you would do .761 on top and then .01 in the denominator.

Sana Nagori 2H

You use the Nernst Equation so you are given products and reactants molarity for Q. T= 298 and R=8.314. n is the mol of electrons transferred and then F is a constant. Pretty much all you need to calculate is E naught from the table and plug everything into the equation. To calculate E naught do the...

Sana Nagori 2H

does the order of the shorthand notation matter?

Sana Nagori 2H

you might be forgetting to convert to kJ. That's what was happening to me and it took so many tries for me to figure that out.

Sana Nagori 2H

I was stuck on this one too so thanks!

Sana Nagori 2H

doesn't isothermal mean irreversible or is that not always the case?

Sana Nagori 2H

I think you can just divide the number of points earned by the total points possible to find out right? Since it is a straight scale

Sana Nagori 2H

I think it is to find the heat capacity of the calorimeter so that you can use it to find the heat released in another reaction

Sana Nagori 2H

I didn't understand this problem either so I just skipped it

Sana Nagori 2H

Try studying in a similar environment as your exams and build up your concentration by using timers

Sana Nagori 2H

I have to cram for my 7B midterm on Monday but I have been binging episodes of Lucifer in between study sessions

Sana Nagori 2H

I was also stuck on this so thank you!

Sana Nagori 2H

Yeah it's a bit confusing with all the different units going on. I just write out all the units when doing calculations so I can check if they are crossing out.

Sana Nagori 2H

Jalyn Davis 3D wrote:
Sana Nagori 2H wrote:Was friday's lecture part of outline 4 stuff?

Based on Lavelle's email from yesterday, it seems like Friday's lecture was the end of outline 4, so it is the last lecture that includes midterm content.

ah ok thank you! Guess I actually have to watch it now ://

Sana Nagori 2H

Same, it seems like there are so many equations to keep track of

Sana Nagori 2H

K as in Kelvin?

Sana Nagori 2H

I'm currently watching Lucifer and started Supernatural! I'm also looking forward to watching World War 2 in Color once midterms end!

Sana Nagori 2H

Namratha Gujje wrote:I have been watching Teen Wolf which honestly is a really good show. I wasn't expecting it to be this good when I first started it. 10/10 would recommend.

I was obsessed with teen wolf in middle school. I miss those days

Sana Nagori 2H

Ls7c, maybe chem 14c and maybe ls23l. I don't feel like taking any classes tbh

Sana Nagori 2H

Personally doing an absolutely poor job of it. It was much easier to do with in-person classes because there was a clear distinction between classes and your free time. I just try to do my relaxing during the day when I'm most unproductive anyway and then study at night when I feel more awake.

Sana Nagori 2H

Was friday's lecture part of outline 4 stuff?

Sana Nagori 2H

Maybe you need to spend some time focusing on the concepts and understanding what is truly happening. I think it makes approaching problems much easier and is especially helpful if you're stuck on a problem.

Sana Nagori 2H

Janna Shakiba wrote:
When you say outline questions, are you referring to the problems listed in the syllabus?

Yes! They are on the syllabus and also at the top of the outlines that the professor has on his website. It's just the relevant questions in the textbook.

Sana Nagori 2H

This may seem counterintuitive, but sometimes just taking a day off is the best thing you can do for yourself. There are days where I know even if I force myself to study, I won't actually retain anything. I take those days to recharge, do something to de-stress and hopefully bounce back the next da...

Sana Nagori 2H

As most people will say, the textbook and the outline questions are your best friend. I haven't had time to go to any UA sessions this quarter, which are good extra practice, but even doing the textbook problems made me feel better about the material!

Sana Nagori 2H

A Thousand Splendid Suns is one of my favorites but maybe not the happiest read. Station Eleven is also a cool book, especially since it's set in a post-pandemic world.

Sana Nagori 2H

One mistake I was making was that I didn't realize there were solids as the reactants. There will be work done if the products have more moles of gas and since the reaction goes from 0 to 1 mole of gas then it is doing work.

Sana Nagori 2H

I'm still mentally on midterm 1

Sana Nagori 2H

This was my exact same problem. Last quarter I finished the exams at least 10 minutes early but I guess the content this quarter is a little more calculation heavy. I guess we just need to get more practice!

Sana Nagori 2H

pretty sure you can yup

Sana Nagori 2H

It's an inert gas so it won't be taken into account for Le Chateliers principle

Sana Nagori 2H

writing out your units is always helpful in calculations so you can keep track of what cancels out and whether you end up with the correct units needed for you answer.

Sana Nagori 2H

I'm probably taking it in fall or even later

Sana Nagori 2H

It takes about a week to two to get them out usually.

Sana Nagori 2H

I was confused by this too! I just used the Kb equation and ended up solving for [B]

Sana Nagori 2H

That's so nice thanks!

Sana Nagori 2H

Janna Shakiba wrote:So we will need 2 devices to take the midterm like last quarter?

yes pretty much. Most people take the exam on their laptop and then use their phones for the zoom

Sana Nagori 2H

No I don't look at the unassigned ones. The ones on the outline seemed to be good enough for 14A

Sana Nagori 2H

As most people said, I found doing the textbook/outline questions at least twice helped me the most and then looking up random practice problems online for extra practice

Sana Nagori 2H

I've been doing such a poor job of exercising my body but these are all great ideas!

Sana Nagori 2H

Hi! For this one, I would first figure out which equations that were given will give us the reaction at the top. I would focus on getting all of the species on the correct side of the equation to match the one at the top. For example, I would flip N2 + 3H2 <-> 2NH3 so that the species are on the sa...

Sana Nagori 2H

I think delta H is what we look at because it tells us whether the heat of the system increased or decreased with the reaction

Sana Nagori 2H

For this problem, I set up an ICE box and used it to find x. The initial pressure of PCl5 would be 0.0370 bar and the change would be -x, while the other initial pressures would be 0, and the change would be +x. After using Kp and finding x, you would calculate the pressures at equilibrium and add ...

Sana Nagori 2H

I'm also kind of stuck on this one. Should we be adding/subtracting these equations and using the inverse K value when possible?

Sana Nagori 2H

Kaiya_PT_1H wrote:Not sure if this helps, but I spent a long time on this trying to do the quadratic formula when you can just square root the Kc formula and the value for Kc to solve for x.

I wish I saw this beforehand. I also did the whole quadratic formula out haha

Sana Nagori 2H

I find textbook problems and youtube videos help me the most

Sana Nagori 2H

Sapling is our graded homework but it's only graded on completion! The textbook problems given in the outlines are the ones for extra practice and are optional

Sana Nagori 2H

It's just rearranging the equation and realizing that molarity=concentration= mol/L

Sana Nagori 2H

605291562 wrote:On sapling you can find a pdf version you can download which is probably easiest, they also have all the odd answers in the back of the book.

Definitely suggest downloading the pdf if you plan on doing a lot of practice problems.

Sana Nagori 2H

Also he showed that in aqueous solutions even if you included H20 in both the reactants and products it would cancel out.

Sana Nagori 2H

Practice problems are the best preparation! Also on days you're lacking motivation I highly suggest going to UA sessions. You end up getting some extra practice and it isn't as painful as forcing yourself to stare at textbook problems for hours.

Sana Nagori 2H

There is also a free online pdf that you can download. I find it easier to navigate.

Sana Nagori 2H

I don't think it is!

Sana Nagori 2H

I think like NaCl would be other since it is not an acid or base

Sana Nagori 2H

Oxides and Hydroxides of group 1 and 2 elements!

Sana Nagori 2H

Racquel Fox 3L wrote:
Why would N want a +1 charge thought?

It's not that N would WANT a +1 charge but more that oxygen really doesn't want one.

Sana Nagori 2H

Just finished my last exam so that's a big relief! Now I only have an essay left.

Sana Nagori 2H

stronger acids are more stable after they have lost their H+. If a molecule loses a proton and is stable it is less likely to want to pick one up again and therefore will stay completely deprotenated so that's why a stronger acid will have a more stable conjugate base!

Sana Nagori 2H

this might just be me but I actually like listening to songs with words in them. Usually I turn them up loud enough where it just becomes background noise and I don't get distracted but it sounds counterintuitive.

Sana Nagori 2H

I think it's because bases with Nitrogen are weak bases generally. Also the minus charge on BrO- would really want to form a bond with a hydrogen because it's an ion and wants to get rid of that charge and that is why it's the stronger base

Sana Nagori 2H

I think ion-dipole is stronger than H-bonds

Sana Nagori 2H

I don't know about the hydrates part but for determining the pH, the positive charge on the TM cations would want to bond with the partially negative oxygen atom of water thus weakening a O-H bond and releasing a H+ so that is why the pH<7

Sana Nagori 2H

I think because if oxygen donated a pair it would end up with a positive formal charge and oxygens do not want that.

Sana Nagori 2H

do we have to know Kw?

Sana Nagori 2H

I kinda just thought about it where usually nonmetal oxides are acids and that's why SO3 is the acid but I'm not sure if that's correct

Sana Nagori 2H

Thank you! The workshop was really helpful!

Sana Nagori 2H

single bonds are always sigma bonds so they can rotate. However, a double bond has an addition pi bond which limits the rotation and essentially locks the sigma bond in place because they are at 90 degrees to each other (I think). This is why a double and triple bond would not be able to rotate.

Sana Nagori 2H

when naming, the cations outside the bracket like Na or K wouldn't have prefixes and the same with anions like Cl on the outside of brackets. They would just be potassium or chloride.

Sana Nagori 2H

yes! Copper, silver, and gold off the top of my head also have exceptions

Sana Nagori 2H

There is a list on the professors website that has the names of the ligands. However, it doesn't specify the number of bonding sites for each. From what I've heard, the main polydentate ions to know are oxalato (2), carbonato (1 or 2), en (2), dien (3), and edta (6). Someone else can let me know if ...

Sana Nagori 2H

yes you have to check if the TM compound has an overall negative charge. It's easy in these questions because it is just the anion but sometimes when there is a cation (like Na or K) present the negative charge isn't written and you have to look at the two components separately to realize the TM com...

Sana Nagori 2H

some ligands have special names when naming coordination compounds. Water is aqua, not hydro. Aqua comes first alphabetically which is why aqua comes first and then pentacyano. Also, since the compound has an overall negative charge, the TM is named with a "ate" ending- cobaltate- to signi...

Sana Nagori 2H

CesarLec1 wrote:I believe that for our purposes, when we see a molecule with 6 carbon atoms, it will most likely be in a ring structure

Yeah usually when there aren't enough Hydrogens to fill out a zigzag structure I try to fit it into a ring structure.

Sana Nagori 2H

Maybe someone out there has a more definite answer

Sana Nagori 2H

This is actually an interesting thought. Maybe they can briefly cancel but overall it will remain what it dominantly is.

Sana Nagori 2H

When a molecule has resonance where a double/triple bond can be found in multiple locations, the electrons in those bonds are delocalized. If a molecule has resonance, the pi bonds making up those double/triple bonds are delocalized.

Sana Nagori 2H

Marcus Lagman 1B wrote:Hello!

I do think you are correct! Here is an image of where the bonding sites would occur:

this is a really helpful image!

Sana Nagori 2H

If two atoms are "bound", they have a bond between them. If this bond is a sigma bond (a single bond), then the atom can rotate freely. Once the bonds become double or triple, there are pi bonds that inhibit this freedom and the atoms can no longer rotate from the plane they are in.

Sana Nagori 2H

Yes but it still needs to have dipole moments. Molecules with only H-C bonds will never have a significant difference in electronegativity so no matter the shape they will never be polar.

Sana Nagori 2H

I haven't caught up on all the lectures so I don't know what it means in this context but orthogonal just means perpendicular.

Sana Nagori 2H

I think I will probably watch some youtube videos on stuff I'm still confused on and just try to do as many practice problems as I can because I learn better by actually doing problems and not just watching lectures.

Sana Nagori 2H

Yeah you're probably right because an odd number electrons means it is a radical

Sana Nagori 2H

Ground state configuration would be the configuration that you expect to see then following the rules that we learned about in class like Pauli's Exclusion Principle and Hunds rule. In an excited state, you'll see in electron in a higher energy level than expected. For example, Helium's ground state...

Sana Nagori 2H

There's a bit in the textbook that talks about this regarding boiling points where it said that LDFs became more important than polarity but honestly it confused me.

Sana Nagori 2H

I just had mine today and I'm just glad it's over tbh. I've been watching Netflix all day since I took it.

Sana Nagori 2H

I don't think we're supposed to have lecture because on CCLE it says that there's no school.

Sana Nagori 2H

How do we know when to do the lewis structures with the brackets and no lines vs the lewis structures with the lines (for covalent molecules). Would we have to be given the electronegativity and calculate whether the difference is larger than 2 to determine its an ionic bond? Or at least told that i...

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