CHEMISTRY COMMUNITY

Janna Shakiba

Thank you guys for all this great advice! It really helped me calm down before taking the final, which I think went okay! And now it's time to move on to the next final...story of our lives

Janna Shakiba

I want to take 14C but there aren't any spots right now :( I'm hoping to get in, though!

Janna Shakiba

Hi there, I don't know about anyone else but I am really starting to feel nervous about the final tomorrow, like a prolonged panic attack. I've been studying a ton so I think I'll do okay, and I know it's not the end of the world if I don't, but I just can't seem to calm down. I'm worried I'm going ...

Janna Shakiba

Dr. Lavelle, thank you for making me enjoy chemistry for the first time in my LIFE!

Janna Shakiba

I am really inspired by all you freshman who have been hanging in there for so long now and just patiently waiting for your ~real~ college experience to begin.

I promise it will be so so worth it! :)

Janna Shakiba

This Wednesday from 4-5pm is a kinetics review! I've attached the zoom link.

https://ucla.zoom.us/j/94056295996?pwd= ... 09#success

Janna Shakiba

The key is to figure out what equations to use, based on whether or not the reaction is zeroth order, first order, or second order. From there, it's pretty easy!

Janna Shakiba

I suggest using the outlook calendar on your laptop/phone. This helps me stay organized, but it also allows me to visually see chunks of time during my day that are empty for me to do whatever I want with.

Janna Shakiba

I'd recommend that every morning you figure out what you NEED to get done that day, and what you want to get done that day. The key here is to recognize that you will live if you don't get everything you want to get done today done. When you take a second to think about it, there are few things we a...

Janna Shakiba

[quote="Mitzy Garcia 1k"]For Cl2O7(g)+H2O2(aq)⟶ClO−2(aq)+O2(g): 1. Multiply 4 to H202 and O2: Cl2O7(g)+4H2O2(aq)⟶ClO−2(aq)+4O2(g) 2. Balance Cl Cl2O7(g)+4H2O2(aq)⟶2ClO−2(aq)+4O2(g) 3.To balance O atoms balance it by adding 3 H20 Cl2O7(g)+4H2O2(aq)⟶2ClO−2(aq)+4O2(g) +3H20(l) 4. Balance out ...

Janna Shakiba

Hi! I need help balancing this.

Janna Shakiba

Janna Shakiba

The unbalanced equation for the reaction of gold with aqua regia is given. Add the stoichiometric coefficients to the equation to balance it.

This is what I got but it's wrong:
Au(s)+3NO−3(aq)+6H+(aq)⟶Au3+(aq)+3NO2(g)+3H2O(l)

Can someone please show me their balanced equation for this problem?

Janna Shakiba

Can someone please show me how they balanced these equations? I'm good on finding the oxidizing and reducing agents but I can't seem to get the equations right. Identify the oxidizing and reducing agents in the skeletal (unbalanced) reaction. Then, balance the reaction, including the phase (solid, l...

Janna Shakiba

Please help.

Identify the oxidizing and reducing agents in the skeletal (unbalanced) reaction. Then, balance the reaction, including the phase (solid, liquid, etc.) of each species. The reaction takes place in basic aqueous solution.
Cl2O7(g)+H2O2(aq)⟶ClO−2(aq)+O2(g)

Janna Shakiba

Please help.

Write a balanced overall reaction from these unbalanced half-reactions.
In⟶In3+
Cd2+⟶Cd

Janna Shakiba

I felt so much better about my performance on midterm 2 and boy, did that make de-stressing a lot easier!

Janna Shakiba

Does anyone know if chem 14D is being offered this summer?

Janna Shakiba

I'm not sure if anyone has said this yet, but maybe consider your standards for yourself and loosen them up a bit. I know we are UCLA kids and we are born perfectionists, but recognize that you are being forced to continue your education through an incredibly hard time, and that is no easy feat! The...

Janna Shakiba

I believe weeks 4-6.

Janna Shakiba

Hi, I do not know (sorry!), but I was wondering if you were able to solve the rest of the problem? If so, do you mind sharing your steps? I'm stuck on this one.

Janna Shakiba

Hi so this problem looks really long and intimidating... can somebody please tell me how they started it? I am scared I'll do the whole thing wrong and have to redo it lol. Three liquid samples of known masses are heated to their boiling points with the use of a heater rated at 525.0 W. Once the boi...

Janna Shakiba

Can someone please walk me through the steps for solving this problem? A particular container holds 4.07 mol of neon gas. The volume of this container can be altered by sliding a piston in or out. The volume is changed from 7.60L to 11.00L while at the same time the temperature is changed from 299K ...

Janna Shakiba

Can someone please walk me through how they solved this? For a gaseous reaction, standard conditions are 298 K and a partial pressure of 1 bar for all species. For the reaction 2NO(g)+O2(g)↽−−⇀2NO2(g) the standard change in Gibbs free energy is ΔG∘=−69.0 kJ/mol. What is ΔG for this reaction at 298 K...

Janna Shakiba

Kristine_Aramyan_3K wrote:
Janna Shakiba wrote:
Kristine_Aramyan_3K wrote:does anyone know the amount you have to collect for a P/NP for this class?

You need a 75 to pass.

75%?

Yes, a 75%.

Janna Shakiba

Exactly, so we use enthalpy of fusion!

Janna Shakiba

My family has an ongoing debate if adding salt to pasta water makes the water boil faster or slower. The argument for faster is that adding salt disrupts the surface tension of the water, and contributes to it boiling faster. The argument for slower is that salt raises the boiling point of the wate...

Janna Shakiba

Mari Williams 1K wrote:My brother and I once shattered a glass pan of brownies after putting it on a cold metal table straight out of the oven...truly tragic

Lmao I've done this too

Janna Shakiba

Hey Lillian, I get it! I've been having the same problem where I just feel physically incapable of doing work sometimes, which is... not great. I like to make lists of what I have to do and when the things need to be done by, and I find it helpful to break up large tasks ("study for midterm&qu...

Janna Shakiba

I sympathize with you. It's tough because there are so many different ways of studying/preparing for the midterm, which is a good thing but can also be extremely overwhelming and make you not want to do anything! I would say break it down into small goals: attend one UA session this week, see how yo...

Janna Shakiba

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! When you say outline questions, are you referri...

Janna Shakiba

Awww I love seeing everyone support each other and bond over our shared stress. It makes online learning just a little less lonely :')

Janna Shakiba

Random but is anyone simultaneously taking 14BL right now and want to form a study group?

Janna Shakiba

Thank you for saying this. I studied pretty hard for the midterm and even though I may not have done as well as I wanted to, I'm proud of myself for trying my best and all of you should be too :)

Janna Shakiba

Hi there, I have been reflecting on midterm 1 and I know the scores have not come out yet but I personally feel I did not do well. For me, the issue was not solving the problems, but solving them in the time allotted. What happened with me was I would solve a long math problem and not get an answer ...

Janna Shakiba

So we will need 2 devices to take the midterm like last quarter?

Janna Shakiba

Angel More wrote:Last time we were sent links prior to our exams. I think that is how it is going to be this time as well!

Awesome, thanks!

Janna Shakiba

Kristine_Aramyan_3K wrote:does anyone know the amount you have to collect for a P/NP for this class?

You need a 75 to pass.

Janna Shakiba

Do we use our discussion zoom link to take the midterm next Friday during lecture time?

Janna Shakiba

Does anyone know why it's not open book? Weren't the 14A midterms open book?

Janna Shakiba

Please explain the steps for solving this if you can:

The reaction N2O4↽−−⇀2NO2 is allowed to reach equilibrium in a chloroform solution at 25 ∘C. The equilibrium concentrations are 0.344 mol/L N2O4 and 1.96 mol/L NO2. Calculate the equilibrium constant, Kc for this reaction.

Janna Shakiba

At equilibrium, the concentrations in this system were found to be [N2]=[O2]=0.200 M and [NO]=0.500 M.

N2(g)+O2(g)↽−−⇀2NO(g)

If more NO is added, bringing its concentration to 0.800 M, what will the final concentration of NO be after equilibrium is re‑established?

Janna Shakiba

I believe you need to use the molar concentrations instead of the actual number of moles in your calculations. It helps me to look at the givens in the problem and if they don't give molar concentrations(M) of the products or reactants, then you need to calculate them using moles/liter. In this cas...

Janna Shakiba

Consider the reaction at 500°C N2(g)+3H2(g)↽−−⇀2NH3(g) Kc=0.061 If analysis shows that the composition of the reaction mixture at 500°C is 0.571 mol⋅ L−1N2, 2.77 mol⋅ L−1H2, and 4.40 mol⋅ L−1NH3, what is the value of the reaction quotient Q? Can somebody please walk me through their steps for this p...

Janna Shakiba

I believe you need to use the molar concentrations instead of the actual number of moles in your calculations. It helps me to look at the givens in the problem and if they don't give molar concentrations(M) of the products or reactants, then you need to calculate them using moles/liter. In this cas...

Janna Shakiba

At a certain temperature, the given reaction has an equilibrium constant of Kp=375

PCl3(g)+Cl2(g)↽−−⇀PCl5(g)

PCl5 is placed in a sealed container at an initial pressure of 0.0750 bar. What is the total pressure at equilibrium?

Janna Shakiba

Consider the reaction of NH3 and I2 to give N2 and HI. 2NH3(g)+3I2(g)↽−−⇀N2(g)+6HI(g) K Using two or more of the given equations, determine the equilibrium constant, K, for the reaction of NH3 with I2. H2(g)+I2(g)↽−−⇀2HI(g) Ka=160 I2(g)↽−−⇀2I(g) Kb=2.1×10−3 N2(g)+3H2(g)↽−−⇀2NH3(g) Kc=3.6×10−2 H2(g)+...

Janna Shakiba

At a certain temperature, 0.900 mol SO3 is placed in a 4.00 L container. 2SO3(g)↽−−⇀2SO2(g)+O2(g) At equilibrium, 0.140 mol O2 is present. Calculate Kc. I attempted this a few times now and am stuck. I created an ICE table and solved for x and got 0.14. I then plugged that in to the equation with x ...

Janna Shakiba

Hi! I am wondering if there is a way to solve this kind of question without doing it the long way (aka using the quadratic formula): 26. A mixture initially consisting of 0.250 N2 (g) and 0.500 M H2 (g) reacts to form NH3 (g) which is 0.15 M NH3 (g) at equilibrium. Calculate the concentration of N2 ...

Janna Shakiba

19. Calculate the reaction quotient, QC, from the following equilibrium data collected in a 3.00 L sealed reaction vessel for the reaction: AsH3 (g) ⇌ As (s) + H2 (g) AsH3 = 5.55 x 10-4 mol, As = 3.31 x 10-3 mol, H2 = 1.23 x 10-3 mol. I know this seems like an easy problem but for the life of me I c...

Janna Shakiba

This post made me realize that I probably SHOULD have a pre finals ritual but I don't.

Janna Shakiba

I am going skiing!!!

Janna Shakiba

As a chemist myself, I must say that the temperature does indeed influence the pH of the solution. At high temperatures, the volume of a given solution will expand. This causes the concentrations of solutes to decrease even though the amount of solute remains the same; the opposite occurs at low te...

Janna Shakiba

I completely understand how you feel, but I don't think Lavelle offers extra credit(or at least hasn't in the past). I'm sure you worked really hard throughout the quarter given the unfortunate circumstances. Thank you so much. I just wasn't able to do as well as I'd hoped I would and I have a feel...

Janna Shakiba

Chem_Mod wrote:These posts are points, fairly easy points and credit.

I understand that, but I think given the unusual circumstances this quarter it's not absurd to ask for a separate extra credit assignment :(

Janna Shakiba

I'm confused about how the final will be since everyone is taking it at the same time? Should we still just use our normal discussion link?

Janna Shakiba

It's bidente because it needs to receive two electrons total to get to its ground state.

Janna Shakiba

I am wondering if there is going to be any extra credit offered on the final exam? Or perhaps just an extra credit homework assignment or something? I calculated my grade in the class and I can't get an A in the class even if I get 100 on the final which is very discouraging. I feel like this quarte...

Janna Shakiba

I don't know if you saw, but there's a great table in Sapling that summarizes all of them. If you can't find it email me and I'll send you a screenshot.

Janna Shakiba

If you've read any of my other posts by now, you can probably tell I suck at drawing lewis structures.

Please help:

Draw the Lewis structure of AsO3−4 showing all lone pairs.

Janna Shakiba

Please help:

Draw the structures of
H2CCH2
H2CCCH2
H2CCCCH2
Be sure to include all atoms.

Janna Shakiba

Can someone please help with this question:

Draw the three possible structures of C3H4
. Be sure to include all atoms.

Janna Shakiba

Can someone please help with this question?

An organic compound that is distilled from wood has a molar mass of 32.04 g/mol. Its composition by mass is 37.5% carbon, 12.6% hydrogen, and 49.9% oxygen. Draw the lewis structure of this compound.

Janna Shakiba

It honestly just depends on your learning style. If you hate asking questions and prefer structure, go to the step-up sessions. If you learn better by engaging with someone and like being free to talk about multiple ideas you have on a particular problem, go to the drop-in sessions. Of course, if yo...

Janna Shakiba

A good trick for figuring out which molecule has the higher boiling point is to look for which one has an OH- group (or the most OH- groups).

Janna Shakiba

Will there be a review session for the final exam? I just feel like we've covered so much material and the fact that the final is cumulative is stressing me out.

Janna Shakiba

Is it possible that it's asking you to access the lecture through a VPN? If so, I can give you the steps on how to fix that.

Janna Shakiba

Great question! The fact that you are asking this shows you are very smart. De-stressing looks a little different for everyone, but here are some things that work for most people: - Take a long bath while listening to calming music - Read a book just for fun - Write a thank you note to someone who h...

Janna Shakiba

Should we expect midterm 2's difficulty to be the same as midterm 1 or will it be harder?

Janna Shakiba

If you would like me to show you my work for Sapling hw problem #17, email me!

Janna Shakiba

Hey there! So I took chemistry summer after my freshman year of high school and then took AP chem during sophomore year. In hindsight, this was probably not the smartest decision because I forgot pretty much everything I knew about chem by sophomore year of college. So even though I have a backgroun...

Janna Shakiba

Hi there,

Thank you! I took all this into consideration but I am still having trouble. I'm wondering if there is a glitch in the system because I feel like I've tried every possible combination. Would you mind sending me a picture of your work?

Janna Shakiba

Hi there,

I have been stuck on this seemingly simple problem for a while now and was wondering if I could get some help.

The question is:

Classify each species as a Lewis acid or a Lewis base.

and these are the molecules given:

Cu2+, SO2, S2-, B(OH)3, NH3

Janna Shakiba

Two chemists go to a bar. The bartender asks them for their order. The first chemist says "I'll have H20," and the second chemist says "I'll have H20 too!" The bartender makes them their drinks and the second chemist drops dead. The first chemist accuses the bartender of poisonin...

Janna Shakiba

Taking them at the same time is totally doable! I am taking 14A and 7C right now and my schedule feels very balanced. Also, there are so many pre-med requirements, you're going to have to double up at some point!

Janna Shakiba

Have you checked your chemistry community grade yet on myUCLA? It will be Weeks 1-4, so the max points you can have is 20. If you got a 20, then you're doing everything right!

Janna Shakiba

Can we expect the difficulty of Midterm 2 to be the same as Midterm 1? Or will it be significantly harder?

Janna Shakiba

Oxygen and Magnesium went on a date...OMg!

Janna Shakiba

My TA said we can expect to get our scores by the end of Week 5.

They can't start grading until everyone has finished taking the exam. The last exam was the makeup exam on Friday at 3pm.

Hope this helps!

Janna Shakiba

I am not sure if I'm using the right value for m.

Is it 9.11x10^-31?

Janna Shakiba

Hey guys, thank you for these tips but I am still really stuck on this question. I did:

(6.26x10^-34) / (6.31 x 10^23) (442.4) to find the wavelength. My units gave me my answer in m like the question asks for, but I still keep getting it wrong. I'm not sure what else to do...

Janna Shakiba

The average speed of a diatomic fluorine molecule at 25 ∘C
is 442.4 m⋅s−1
. What is the average wavelength of a fluorine molecule at this temperature? Assume that the molecule acts as a single particle.

Janna Shakiba

You use an electron microscope in which the matter wave associated with the electron beam has a wavelength of 0.0457
nm. What is the kinetic energy of an electron in the beam, expressed in electron volts?

Janna Shakiba

Does anyone know how many questions will be on the midterm? I'm a bit concerned with the short 50 minute time limit... In an earlier post, someone said it will be about 10 questions. I was concerned about the time limit too, but if you have been able to do the post-assessments in under 50 minutes t...

Janna Shakiba

Tobie Jessup Section 3D wrote:Do you guys know if the midterm is all multiple choice?

Yes, it is all multiple choice.

Janna Shakiba

Does anyone know if we can use our ipads to do our work on the midterm? I know this is probably a long shot with how far they've gone to prevent cheating but my TA didn't seem to think it was totally out of the question. Has anyone else's TAs said anything about this? If you are using your iPad to ...

Janna Shakiba

Is there a way to search up if someone has posted something similar to (or exactly the same) as my question? For instance, could I look up "Sapling HW Week 3" somewhere to see what people have already posted about that? I just don't want to keep making new posts for all my questions if som...

Janna Shakiba

Wow, I'm dumb. All I had to do was click "Quick Links" and there it was: "Your posts"

However, if I post in a forum with a huge amount of replies, it's still a little annoying to have to scroll down to find mine. Is there a way to do this other than command f?

Janna Shakiba

I am wondering if there is a way to see which of my posts have gotten replies, because I have to keep going back and searching for the post to figure out if someone has responded yet.

Janna Shakiba

Are discussion sections every week mandatory? Or are they only mandatory when there's an exam?

Follow up question:
Will we take the midterms and final during discussion section?

Janna Shakiba

So we don't have any HW to turn in for weeks 2 through 4 other than our 5 chemistry community posts every week, correct? Since all the Sapling HW isn't due until Sunday night week 4?

Janna Shakiba

The e-textbook is the link that Dr. Lavelle sent in one of his earlier emails. If you click on that and follow the instructions you will automatically get the e-textbook.

Janna Shakiba

The e-textbook is the link that Dr. Lavelle sent in one of his earlier emails. If you click on that and follow the instructions you will automatically get the e-textbook.

Janna Shakiba

Hi Ashley- one question: I am on track to graduate from UCLA with a bachelor's in Neuroscience in 3 years (as in 3 years at UCLA total) and I'm wondering if med schools will look down on this. I came into college with a lot of credits because I did a few college classes in high school and I feel tha...

Janna Shakiba

Thank you, Ashley. I feel like my perspective towards 14A has changed after reading your post. I was terrified of this class because I struggled a lot in high school chemistry. While I'm pretty positive I don't want to study chemistry as a career, I should be more open to the idea of learning it now...

Janna Shakiba

Are these separate from the 10 Sapling HW problems due tonight? If so, where are these problems? My textbook code has come in the mail so I have full access to everything. Thanks!

Janna Shakiba

Thank you so much everyone!

The problem was actually that I was using the molar mass of Cu(NO3)2 instead of CuNO3 which was why I kept getting the wrong answer. Note to self and everyone else: double check your compound formulas!

Janna Shakiba

Consider the nucleophilic addition reaction of 2‑butanone with excess propyl magnesiumbromide, made in situ by reacting 1‑bromopropane with metallic magnesium, to make 3‑methyl‑3‑hexanol. Reaction scheme where 2-butanone (d = 0.81 g/mL), 1-bromopropane (d=1.35 g/mL), and magnesium react to form 3-me...

Janna Shakiba

Caproic acid has the odor of goats. (In fact, Capra is the genus of the domestic goat.) The compound contains only C, H, and O and was experimentally found to have a molar mass of 110±10 g/mol . When a 1.000 g sample of caproic acid is burned in excess oxygen, 2.275 g CO2 and 0.929 g H2O are collect...

Janna Shakiba

If 3.39 g of CuNO3 is dissolved in water to make a 0.580 M solution, what is the volume of the solution in milliliters?

Search found 100 matches