CHEMISTRY COMMUNITY

Lorraine Medina 3E

i think we can still see all the posts and threads, but i'm not sure if we are still allowed/able to post. hope this helps!

Lorraine Medina 3E · Re: Final on 3/13 the final starts at 9:30 am. hope this helps!

the final starts at 9:30 am. hope this helps!

Lorraine Medina 3E

the final is cumulative. hope this helps!

Lorraine Medina 3E

i would assume this would be the case. hope this helps!

Lorraine Medina 3E

i think we will be ending new material on wednesday and having a review lecture on friday. hope this helps!

Lorraine Medina 3E

yup, it's combined with week 10 and will be due the friday of week 10 (3/12). hope this helps!

Lorraine Medina 3E · Re: Final Exam Time the final is from 9:30 am to 11 am! hope this helps!

the final is from 9:30 am to 11 am! hope this helps!

Lorraine Medina 3E

it's on sunday, march 14th at 9:30 am! hope this helps!

Lorraine Medina 3E

i see my grade on ccle! hope this helps!

Lorraine Medina 3E

Hi Monica! I think we should be finished with new material by Wednesday. Hope this helps!

Lorraine Medina 3E

Hi! I know this is question is geared towards 14BL rather than B, but does anyone know the likelihood of getting off the waitlist for Chem 14BL during Summer Session A? or if they will be adding more spots to the class to accommodate the waitlist? Thanks for the help!

Lorraine Medina 3E

it is cumulative! but i am assuming that the number of questions regarding each section will vary depending on how much time we spent on that section. hope this helps!

Lorraine Medina 3E

i think it depends on your TA, so to be safe maybe continue the 5 posts a week. hope this helps!

Lorraine Medina 3E

i believe those in over-enrollment have priority over waitlist. I am currently waitlisted for a class and this is what MyUCLA told me regarding positions on the waitlist: "For example, if a class has an enrollment capacity of 30 and there are 35 enrolled and there are 5 on the waitlist, your ef...

Lorraine Medina 3E

i would review textbook problems and make sure you really understand why certain steps are taken in solving. also youtube videos are really helpful for review!

Lorraine Medina 3E

check outline 3 and 4 on Lavelle's website! they have a bunch of specific textbook problems that he picked out. hope this helps!

Lorraine Medina 3E

I would just wait it out to see updates, but make sure you're still posting consistently!

Lorraine Medina 3E

Midterm 2 covers until week 6, so it partially covers outline 3 and the entirety of outline 4. hope this helps!

Lorraine Medina 3E

Hi! What bullet point on Outline 3 starts what we need to know for MT2? Thanks for the help!

Lorraine Medina 3E

He said that "8 point questions and 4 point questions, 8 point questions have 4 point partial credit answers" Hope this helps!

Lorraine Medina 3E

it's under grades on CCLE. hope this helps!

Lorraine Medina 3E

I would ask your TA during their OH to review with you as that's how it was for 14a. hope this helps!

Lorraine Medina 3E

they're all updated on CCLE! hope this helps!

Lorraine Medina 3E

i'm assuming it'll just be stuff after midterm one like it was for 14a. hope this helps!

Lorraine Medina 3E

thanks for all the tips y'all! definitely will be using them :) good luck!

Lorraine Medina 3E

Hi! q is negative when the reaction is exothermic (releasing heat) and positive when the reaction is endothermic (heat is added). hope this helps!

Lorraine Medina 3E

Work is negative when a system does work on its surroundings. A larger negative number means more work was done. Hope this helps!

Lorraine Medina 3E

Closed systems don't allow for the exchange of matter. hope this helps!

Lorraine Medina 3E

Hi! N is the number of molecules in the system. Hope this helps!

Lorraine Medina 3E

Hi! From what I understand, Work is the energy transferred between a system and its surroundings. Hope this helps!

Lorraine Medina 3E

I would use the R constant that matches the units given in the problem. Hope this helps!

Lorraine Medina 3E

Hi! Can anyone explain the definition/differences of open, closed, and isolated systems? Thanks so much for the help!

Lorraine Medina 3E

since you’re from a different class last quarter, you only have to do the 50 for this quarter. hope this helps!

Lorraine Medina 3E

i believe some will come from the textbook but not all. hope this helps!

Lorraine Medina 3E

i do not believe there is a reset button, but you can look at your previous attempts. hope this helps!

Lorraine Medina 3E

i think an A is 93-96% while A- is 90-92%

Lorraine Medina 3E

only the amount of posts!

Lorraine Medina 3E

Hi! Up to which lecture number is going to be on midterm 1? Thanks for the help!

Lorraine Medina 3E

Yes, I think it is the same procedure as 14a. Hope this helps!

Lorraine Medina 3E

I think the closer you are to the correct answer, the more partial credit you will receive. Hope this helps!

Lorraine Medina 3E

Dr. Lavelle said x is assumed insignificant when it is less than 10^-4. Hope this helps!

Lorraine Medina 3E

I think it is kj/mol. Hope this helps!

Lorraine Medina 3E

As everyone already said, I don't think we'll have to memorize them considering Dr. Lavelle looked them up during lecture, so I am assuming they will be given during the exam. Also, this link from the Chempendix was given while I was working on Sapling homework: https://sites.google.com/site/chempen...

Lorraine Medina 3E

Hi! For #5 on Sapling, I was confused on why we flip equation 4? Is it simply because the MCL3(s) is needed on the product side rather than MCl3(aq) in the final reaction? I hope this make sense, thanks for the help!

Lorraine Medina 3E

They are on CCLE and MyUCLA, however, I think chemistry community grades are updated just at the end of the week unlike Sapling, which tracks your progress as you do it. Hope this helps!

Lorraine Medina 3E

Maybe the way you input the password was wrong? LL14B21 is the password for his site, hope this helps and you are able to get in!

Lorraine Medina 3E

You can click quick links on the upper left corner and check "your posts" to see if people have replied to your questions. Also, under the submit button for a question/response, there is a box for options where you can click "notify me when a reply is posted." Hope this helps!

Lorraine Medina 3E

The different gas constants are given on the constants and equations sheet that we are allowed to use for tests, and I would decide from there which constant to use by looking for the relevant units. Hope this helps!

Lorraine Medina 3E

Hi! the concentrations of solids and liquids do not change, therefore we omit them. Hope this helps!

Lorraine Medina 3E

Hi! the gas constants are on the constants and equations sheet found on Lavelle's website, and we can use that sheet during tests. therefore, you don't necessarily have to memorize all of them if they are on the sheet, but I guess use the one that has the correct units for the problem. Hope this hel...

Lorraine Medina 3E

I don't think they will be covered in this class, but maybe in other future classes or series. Hope this helps!

Lorraine Medina 3E

Temperature is important, but I think it'll matter more as we move onto more complicated questions. If a temperature is not stated, my TA said to assume it is at room temp which is 25 degrees C. Hope this helps!

Lorraine Medina 3E

Inert gases are non-reactive gases, such as noble gases. Hope this helps!

Lorraine Medina 3E

When K is reversed, it becomes the inverse of the forward reaction, therefore 1/K. Hope this helps!

Lorraine Medina 3E

Kc is used for concentrations while Kp is used for partial pressures. Hope this helps!

Lorraine Medina 3E

yes! we will take our midterms during our lecture time that we picked when signing up for classes. hope this helps!

Lorraine Medina 3E

we get points for both posting and responding! hope this helps :)

Lorraine Medina 3E

we use kelvin when plugging in for the ideal gas law! hope this helps :)

Lorraine Medina 3E

all lectures are asynchronous, and discussions are live (so they are unfortunately are not recorded) but not mandatory. they are pretty helpful though in going over practice problems from the homework! hope this helps!

Lorraine Medina 3E

nope! you are not penalized for incorrect answers, and we have unlimited tries to get the right one. hope this helps!

Lorraine Medina 3E

Hi! How do we know whether to use the forward or reverse reaction and K-forward or K-reverse? I'm not sure if this question is too vague/confusing, but the best example I can give is this question from Sapling: "At equilibrium, the concentrations in this system were found to be [N2]=[02]=0.300 ...

Lorraine Medina 3E

Hi! How do we know whether the change in the C part of the ICE is negative or positive? Like how do we know whether the x (or 2x etc.) is positive or negative? I thought the general trend would be that the reactants have a negative change while products are positive, but I am not sure if I am correc...

Lorraine Medina 3E

you don't have to change the username itself, just your alias that you use so that it has your updated discussion section! just click "register alias and password" on the top and the only thing you have to change is your alias. hope this helps :)

Lorraine Medina 3E

Hi! Our posts stay up as long as chem community stays up! Hope this helps :)

Lorraine Medina 3E

Ka is the measure of the strength of a weak acid. That is, it measures the amount a weak acid will dissociate. The higher your Ka, the stronger your acid and the lower your pH (they're inversely related). pKa is the negative log of Ka just as pH is the negative log of [H3O+]. They too are inversely...

Lorraine Medina 3E

What are pKa and Ka, as in the actual definition of them? Also, how would we calculate them?

Lorraine Medina 3E

Chem_Mod wrote:Only 12 pt questions in MT 1 had partial credit.
8 pt questions in MT 1 did not.
7 pt questions in MT 2 did not.

The final has only 6pt questions.

All the best with finals.

Thank you so much!

Lorraine Medina 3E

Hi! Lewis acids/bases and Bronsted acids/bases are basically saying the same thing but just have two different focuses. Bronsted acids/bases focus on protons, where the acids donate protons and the bases accept protons. Lewis acids/bases however focus on electrons, where the acids accept electrons a...

Lorraine Medina 3E

Hi! This happened to me with the Week 10 Monday lecture, but I was able to instead watch the video 2 option and it worked. Hope this helps!

Lorraine Medina 3E

Hi, does anyone know if we will be receiving partial credit for questions for the final like we did for midterm 1? I remember this being brought up to various TAs for the past couple weeks, but I do not remember if they or Dr. Lavelle ever confirmed nor denied it. Thanks for the help!

Lorraine Medina 3E

wednesday is the last lecture for new content but the friday lecture will be all review. hope this helps!

Lorraine Medina 3E

Yes! If a solution is alkaline, it means it is basic and therefore a pH higher than 7. Hope this helps!

Lorraine Medina 3E

Water can act as both. Hope this helps!

Lorraine Medina 3E

NH4Cl is a salt that can lower the pH by dissociating and donating a proton to H2O. Hope this helps!

Lorraine Medina 3E

A longer bond means that it is a weaker bond, thus making the acid stronger because the atoms dissociate the protons way easier. So basically, the longer the bond, the stronger the acid. Hope this helps!

Lorraine Medina 3E

It's cumulative! So everything we've learned in the course. Hope this helps!

Lorraine Medina 3E

Hi! Does anyone know the cutoffs for letter grades in this class? The only one I know is that "50% or higher is required to pass with a C- or higher," as stated in the syllabus, however I do not know which other percentages correspond with the other letter grades. Any help is appreciated, ...

Lorraine Medina 3E

Hi! What is the difference between weak and strong acids and bases? Thanks!

Lorraine Medina 3E

Hi! I'm just a bit confused on exactly what a Bronsted acids and bases are? Any help is appreciated, thanks!

Lorraine Medina 3E

Sigma bonds are always single bonds while Pi bonds are always involved in double, triple, or more bonds. In a single bond, you only have a sigma bond. In a double bond, you have one sigma and one pi bond. In a triple bond, you have one sigma bond and two pi bonds. Hope this helps!

Lorraine Medina 3E

Hi! Dr. Lavelle said that the textbook specifically uses -ido, and we are free to use either that or -o, but he will be using -o in class and for Sapling. Hope this helps!

Lorraine Medina 3E

Yes, a lone pair counts as a region of electron density. Hope this helps!

Lorraine Medina 3E

I'm pretty sure we will have to memorize the shapes as well as the bond angles. Hope this helps!

Lorraine Medina 3E

You can use bent or angular for the name. Hope this helps!

Lorraine Medina 3E

I'm pretty sure we'll have to memorize the shapes and bond angles. Hope this helps!

Lorraine Medina 3E

The dipole moments cancel out. Hope this helps!

Lorraine Medina 3E

The 60 degree angle bond comes from the triangle that the 3 carbons make. Hope this helps!

Lorraine Medina 3E

We would look at intermolecular forces in order to understand what is occuring between molecules. Hope this helps!

Lorraine Medina 3E

I'm assuming it'll take about the same amount of time as MT1, so hopefully we will get it by next week. Hope this helps!

Lorraine Medina 3E

Hi! The central atom is always the least electronegative and in this example it is carbon. Since Carbon in CH3CL is bonded to each atom, the molecule consequently has 4 bonding regions with no extra electrons/lone pairs. Therefore, its VSEPR notation must be AX4 since the structure describes a cent...

Lorraine Medina 3E

Hi! Today in lecture, Dr. Lavelle said that VSEPR notation uses the letters A, X, and E meaning the central atom, bonded atom, and lone pair respectively. He said that both CH4 and CH3CL are AX4. I understand why CH4 is equal to AX4, but I'm confused as to how CH3CL is equal to AX4. I get that AX4 i...

Lorraine Medina 3E

I remember Dr. Lavelle only using the first diagram during the lecture so maybe that one? I could be wrong though. Hope this helps!

Lorraine Medina 3E

Hi! Couple of questions: An expanded octet is an exception to the octet rule right? Is there a way for us to tell if an element has an expanded octet, or is that just something we kind of have to just memorize which atoms have it and which atoms do not? Also, does anyone have a list of elements that...

Lorraine Medina 3E

Hi! It says in the week 2 outline that we need to be able to " Describe the interpretation of atomic orbitals in terms of probability." Did Dr. Lavelle ever go over this in lecture? I feel like I don't remember probability being talked about at all this course. Thanks for the help!

Lorraine Medina 3E

Hi! Couple questions: What exactly are induced dipoles? Are dipole-induced dipole interactions the same as dispersion/London forces/Van der Waals, or does it have to be induced dipole-induced dipole to be considered the same as dispersion/London/Van der Waals? Thanks for the help!

Lorraine Medina 3E

Hi! Is what was covered today (11/13) in lecture going to be included on MT2? Thanks for the help!

Lorraine Medina 3E

Hi! Will we be asked to draw the resonance hybrid structures for this midterm, or this class in general? Thanks for the help!

Lorraine Medina 3E

Yes! The last 8 bullet points of outline 2 as well as all of outline 3.

Lorraine Medina 3E

Electronegativity and and electron affinity follow the same periodic trend where they increase as it goes up and across the periodic table. Electronegativity is the atom's ability to attract electrons while electron affinity is a neutral atom's likelihood of gaining an electron.

Lorraine Medina 3E

Hi! Does anyone have like a good resource for conceptual questions for this class? I just wanted to know because I know our first midterm had conceptual questions that confused me for a little bit, and since our second midterm is going to mainly be conceptual (I'm assuming?? since there are less cal...

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