CHEMISTRY COMMUNITY

lauren_tran_1L

Thank you so much Dr. Lavelle! Fall and Winter quarter were great and I learned so much!

lauren_tran_1L

You have to look at the oxidation numbers and how much they change! That's why it's 6!

lauren_tran_1L

E naught is at standard conditions!

lauren_tran_1L

Chemical Equilibrium was my favorite and thermodynamics were my least favorite.

lauren_tran_1L

The final is on Sunday instead of Saturday!

lauren_tran_1L

Last quarter I believe that the last lecture was the review? I'm not sure though!

lauren_tran_1L

Is the final exam time the same for everyone?

lauren_tran_1L

Like in the title! Looking for restaurant/boba/dessert places to try when I move!

lauren_tran_1L

You have to write the half-reactions. For example, when there is a reduction half-reaction with Ag+, it will add an electron then become Ag(s). Which would be a solid that adheres to the metal.

lauren_tran_1L

I really recommend Pachinko by Min Jin Lee!

lauren_tran_1L

Yes because in standard conditions there are standard concentrations!

lauren_tran_1L

I think reviewing the old material and doing the new practice problems will help with confidence as well as going to office hours!

lauren_tran_1L

my fave food would probably be sushi!

lauren_tran_1L

I believe it's 50% and the class is out of 400 so it would be 200 points.

lauren_tran_1L

To take the ln out, you raise everything with a base e on both sides. Hope this helps!

lauren_tran_1L

I'm taking LS7B, I didn't get 14C or 14BL :( my pass was too late but I'm taking psych 10, ls40, and a ge instead.

lauren_tran_1L

sleep and not think about thermodynamics and work LOL

lauren_tran_1L

I believe its cumulative so I think the best thing to do is start studying the earlier material as soon as possible! You got this!

lauren_tran_1L

In the textbook problem 4D.11, I'm a little confused about what they are asking for. They just give the delta H° of the reaction and ask for heat absorbed. I associate heat absorbed or heat in general with q, but in this case they are equal to delta H°. Does deltaH° imply constant volume or pressure...

lauren_tran_1L

Internal energy = q + w. But remember the conditions (like when the volume is constant) when it is simplified!

lauren_tran_1L

When work is being done on the system it should be when the gas is being compressed and the work value would be positive with respect to the system.

lauren_tran_1L

From my experience, it is determined by the values found by calculating the equation!

lauren_tran_1L

Maybe also watch some youtube videos to better understand concepts and problems! That definitely helps me a lot! Also, you should do the UA review worksheets they are really good to go over before an exam. Also, when I go through the textbook questions I circle the ones that are difficult and after ...

lauren_tran_1L

I'm currently watching attack on titan and brooklyn 99!

lauren_tran_1L

It should definitely say directly, but if it's indirect, timing is key, and also diagrams should help if you try to illustrate the scenario!

lauren_tran_1L

You can look at the units for each different R and match it to your problem!

lauren_tran_1L

Going back to equilibrium, we can see that K value changes by changing temperature. But if you look at a biological system, for example yourself, elevating your internal temperature would cause your cells to die. You can also think about it in terms of another thing that makes biological systems pro...

lauren_tran_1L

Spontaneity relies on whether the gibbs free energy of a reaction is negative. In simple terms, this means that the reaction is favored to proceed in the fowards direction. I hope this helps!

lauren_tran_1L

I have other midterms to study for :( but after the midterm I got to take a break and watch some Netflix lol

lauren_tran_1L

You're 100% correct!

lauren_tran_1L

You got this everyone! I believe in us! Hopefully the class average is 100% lol

lauren_tran_1L

Yes! I think of this in terms of concentration. Can you measure a concentration of a pure liquid or solid? No.

lauren_tran_1L

I believe Dr. Lavelle said we are only sticking to quadratic equations right now. But make sure to double check the K value! This would give away when you can make the assumption.

lauren_tran_1L

Giving good vibes to everyone who replied! Good or bad we tried our hardest :)

lauren_tran_1L

I usually do the UA worksheets and review past textbook problems I found difficult or do the unassigned ones from the book.

lauren_tran_1L

scared for the midterm

lauren_tran_1L

Hi all! I found my error! Sorry for being vague. I left a negative sign out out my c value!

lauren_tran_1L

Thanks all for replying! I think I get how it will go on test day now!

lauren_tran_1L

In the sapling homework, there are some problems that necessitate the quadratic equation and are close to the assumption. When I tried to use the quadratic equation, however, the discriminant was negative and I couldn't compute the square root. What am I doing wrong here? For reference: Sapling Prob...

lauren_tran_1L

Hi I was wondering if the midterm will be held similarly to how exams were held in Chem 14A. In the syllabus it says we are taking them during our lecture times, so will there be zoom proctoring by our TA's still? I'm sorry if this has been addressed already! Thank you!

lauren_tran_1L

Remember in this problem as well the mole ratios aren't all 1 so there should be an x^2!

lauren_tran_1L

10^-3! But in Dr. Lavelle's Friday lecture, he talks about this is more detail concerning the flexibility of that value and how we can double check when it comes to % ionization!

lauren_tran_1L

Adding all partial pressures gives way for total pressure in a system!

lauren_tran_1L

K would change when the temperature changes. I believe the 6/7 sapling problems tackle this.

lauren_tran_1L

I want to exercise more! I've been very sedentary recently so I want to go outside and run more for instance.

lauren_tran_1L

Remember that this course is very individualistic so keep up with the assigned problems, lectures, and study sessions because it's really easy to fall behind.

lauren_tran_1L

It doesn't change the volume which means it doesn't change the concentration.

lauren_tran_1L

Yes! For example in a decomposition reaction this would be the case!

lauren_tran_1L

The "quickway" is just showing that you determine the way it shifts when the pressure changes the volume by looking at the number of moles. For example, if you double the pressure (halve the volume) it would go to the side with fewer moles.

lauren_tran_1L

Hi Dr. Lavelle,
Thank you for being a great professor for my first quarter at UCLA! I can't wait for more next quarter!

lauren_tran_1L

I'm pretty sure amphoteric compounds react depending on the molecules around them and since water is relatively neutral it would be hard to tell. I don't think it will be asked!

lauren_tran_1L

It really depends. When I was in AP chem, my teacher told us to only think of a few acids as strong acids and all others as weak, but I don't know if that's entirely accurate!

lauren_tran_1L

If you didn't know b was inherently incorrect you can use the process of elimination! For a, when you have higher intensity let's say a brighter light, it doesn't affect the frequency of the resulting kinetic energy. For C, it is saying that kinetic energy and frequency are proportional which they a...

lauren_tran_1L

what is an iron-deficient female?
just a male

lauren_tran_1L

I feel the same way! But it puts him in a hard position because it seems like many are doing well which would make a curve very small to nonexistent :(

lauren_tran_1L

i'm catching up on lectures! so basically tired lol

lauren_tran_1L

Specific to week 9's homework, it's a bidentate ligand which would mean the coordination number would be different!

lauren_tran_1L

I assume because you are assuming the HCL molar concentration was at 100% which would dissociate and give you 100% dissociation of hydronium ions needed to find pH . After dilution, this would be 12% of that value which means that you can take that 100% of dissociation and convert it to a 12 percent...

lauren_tran_1L

I believe that 90% should be the cutoff for receiving an A of any kind. But in some classes I took in the past they curved the final grades so that there could be a specific percentage of students with an A and a B and so forth. But I'm not sure how he's going to go about that. I also agree that 90...

lauren_tran_1L

Do you like chemistry?
Na

lauren_tran_1L

The bent shape can mean different things! If you look up a chart of all the molecular geometries bent can be used for different electron domain geometries. However, in all of those instances, the molecule would be polar to my knowledge because of the lone pairs. The lone pairs make it so that there ...

lauren_tran_1L

Thank you all for all the responses! I'll definitely study everything then!

lauren_tran_1L

Hi! I had a question about something Dr. Lavelle mentioned in lecture, that if an atom has a double bond, then it cannot move around and it is locked into a position by these bonds. I was wondering how this applies to structures with resonance and if the electrons are delocalized? Thanks! Hi! A dou...

lauren_tran_1L

Anna Martin 2l wrote:Could covalent bonds be a part of this list?

Covalent bonds are intrAmolecular forces! That exist within the molecule!

lauren_tran_1L

Like said above, the molecular geometry really depends on the electron domain geometry which includes lone pairs and bonds. If you look up a chart with the different electron domain geometries with their molecular geometry I think it will make more sense! Hope this helps!

lauren_tran_1L

I'm not exactly sure, I mostly try to estimate my grade based on the points I'm receiving (like getting points for chemistry community, the hw, etc). And then based on how my midterms go, I try to see what range I'm in (like whether I'm passing or not lol). I don't think Lavelle has specifically sa...

lauren_tran_1L

Hi Everyone,
I'm not sure if Dr. Lavelle has addressed this already, but is the final exam cumulative, or does it only cover new material? Thanks!

lauren_tran_1L

Hi everyone,
I was wondering what the exact grade scale for this class is in terms of percentages. Like for instance is an A a 94% or 93%? Thanks!

lauren_tran_1L

There are also different notations for double or triple bonds. See a molecule of benzene for more information. Hope this helps!

lauren_tran_1L

I'm confused about how we are going to draw the lewis structures if the test is online. Are we uploading pictures of our drawings? Sorry if this is has already been answered. Thank you!

lauren_tran_1L

I would also like to join if there was a study group made!

lauren_tran_1L

Only molecules with H attached to electronegative atoms, such as N, O, and F can hydrogen bond. Yes this is exactly true! Hydrogen bonds are intermolecular forces like said in this example and are the strongest INTERmolecular force. The hydrogen bonds within a water molecule for instance is not the...

lauren_tran_1L

To see if there is a dipole moment, you look at the elements electronegativity and you subtract the bonded elements electronegativities and the difference allows you to know the nature of their interaction: dipole, nonpolar, etc.

lauren_tran_1L

I believe that even though d is a lower energy level it still has them as valence electrons because the shell is incomplete. I might be wrong! Hope this helps.

lauren_tran_1L

Use hund's rule! This is the diagram with the arrows and boxes to denote orbitals and electron spin! Hope this helps!

lauren_tran_1L

Some tricks I use for finding valence electrons are looking at the electron configuration and seeing which electrons are in the highest energy level and which have incomplete shells, checking that with the element's point on the periodic table, and finally checking that with the electron domain geom...

lauren_tran_1L

Use the kinetic energy equation and de Broglie equation to find the velocity!

lauren_tran_1L

When I watched the lectures I took really thorough notes and I did all the practice problems and the UA worksheets! I'm not sure how I faired yet, but that's what has worked for me.

lauren_tran_1L

There is a proportional relationship between amplitude and intensity in terms of light.

lauren_tran_1L

This is a special phenomenon! It's because the half shell of the p shape is 3 and atoms like to be in full or half-shells. So it would want to get rid of one electron more!

lauren_tran_1L

Are all the tests the same? Because I thought I had a mistake on my version. Let me know if anyone saw this!

lauren_tran_1L

What is the day/time in PST when participation is counted? Thank you!

lauren_tran_1L

Use the equation sheet!

lauren_tran_1L

thank you to everyone who answered my post I really appreciate the help!

lauren_tran_1L

Hi!
I was wondering if we will have to turn in our scratch paper for the midterm and if we have to show our work for each problem. Thanks!

lauren_tran_1L

I usually watch Netflix, read a book, take a nap, hang out with my dogs, or go on a walk! Usually, time away from the screens are the most relaxing for me.

lauren_tran_1L

Yes in his most recent email he sent two links: one to a periodic table and one to a formula sheet that need to printed by the exam. I'm not sure if they're the same on the website, but possibly! Hope this helps!

lauren_tran_1L

Yes I agree that the oxygen in the air is the same as oxygen gas. Naturally, oxygen appears in a pair just like H, N, Cl, Br, etc. Hope this helps!

lauren_tran_1L

There are other factors that affect electrostatic potential energy including the shielding effect by the inner energy levels since the electrons repel the other electrons. They also repel those in the same energy level.

lauren_tran_1L

I think Dr. Lavelle sent an email regarding this question! He attached a periodic table and a constant/equation sheet that we need to be printed before the exam. I hope this helps!

lauren_tran_1L

Could someone explain how 1 mol = 6.022 x 10 23 atoms but can also equal 6.022 x 10 23 molecules? Also, there is a problem in the textbook that says to "Calculate the amount of urea molecules, OC(NH 2 ) 2 in 2.5 x 10 5 g of urea," but gives the answer (3.8 x 10 3 ) in moles. If 1 mol = 6....

lauren_tran_1L

From the E = -hR/n^2 equation we know that the greater the n, the closer E gets to 0. How close is close enough to be considered as 0? In other words, after how many levels does an electron have to move up in order for it to be considered as no longer interacting with the atom? Also, is it differen...

lauren_tran_1L

what is batman's favorite element?
sodium! na na na na na na na na!

lauren_tran_1L

For the hydrogen Bohr model, I was a bit confused about the conservation of energy. Does the electron always start at n=1 since it is a Hydrogen atom? If so, how can the electron end up at a different energy level other than n=1? For example, if the electron is excited to n=3 and drops back down to...

lauren_tran_1L

Shana Patel 1C wrote:Thank you so much, that was so helpful! I'm still shocked that both of you used the same one. Did you learn it in high school, or did I miss something during class?

Yes I learned it in high school!

lauren_tran_1L

Yes. You need to multiply it by it's stoichiometric ratio to the other ion. For instance, 10 H20 molecules for every molecule of Sodium Carbonate Hydrate. Hope this helps!

lauren_tran_1L

I remember it as K.H.D.U.D.C.M : King Henry Doesn't Usually Drink Chocolate Milk. Or Kilo, Hecto, Deca, Unit (for example: gram), Deci, Centi, Mili. Hope this helps!

lauren_tran_1L

It really depends! I rely heavily on the significant figure rules I've learned in high school. Try to read up on significant figures in the textbook. The way I solve problems is by not rounding as much as possible as this can make your data inaccurate. Do your calculations then find the needed signi...

lauren_tran_1L

I believe that the sun emits all forms of electromagnetic radiation. If we had a different sun (a different star) I believe we may have found different amounts of each radiation, as our sun emits an unequal amount of each portion of the spectrum. Hope this helps!

lauren_tran_1L

I'm not 100% sure if it's mandatory, but I have used the free trial and completed the Week 1 homework and it showed up it in the gradebook on CCLE. And I'm pretty sure on the syllabus it makes up a part of the grade percentage. Hope this helps!

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