CHEMISTRY COMMUNITY

Vivian_Le_1L

I've read the Selection Series so many times and love it more and more each time. Definitely recommend! It's kind of like a cross between The Bachelorette and Hunger Games.

Vivian_Le_1L

I've been in love with Japanese 80s City Pop for the past couple of months! It's literally the best! Here's a compilation I found and love a lot. I literally listen to it everyday. https://www.youtube.com/watch?v=0cxJ4Mg_q1M&t=66s

Vivian_Le_1L

I really hope they do hybrid if they don't go with fully remote. I definitely don't want in-person if theres going to be like 400+ students in a lecture. Plus, I really enjoy the flexibility of having classes online. Also, I don't have to stress about walking and making it to my 8am on time if it's ...

Vivian_Le_1L

I'm trying to take BL and CL during the summer but they got filled up when I tried to enroll. :( Does anyone know what the likelihood of getting off the waitlist is? I think I'm like the third person on the waitlist. Aside from that, I have a whole list of TV shows, animes, and kdramas to catch up on.

Vivian_Le_1L

I love being home, but I also want to get out (I think my family is tired of me too lol). I want to dorm if things with covid get better. However, I've also thought about getting an apartment instead too. Either way, I'm probably not going to be home in the fall (or at least try to).

Vivian_Le_1L

You'll probably have to figure them out yourself, but there are lots of videos on youtube that are really helpful. There are general rules to follow when trying to find the oxidation numbers, but it's pretty simple once you get the hang of it.

Vivian_Le_1L

When it's in an acidic solution, then you use H+. When it's in a basic solution, then you use OH-. However, when solving for a basic solution, some people actually solve it like an acidic solution at first and then add OH- to both sides, turning the H+ into water. There are multiple ways to balance ...

Vivian_Le_1L

They are both the same thing. Different people write it differently, but pretty much the same.

Vivian_Le_1L

Some TAs might have posted on CCLE too, but if you can't find them then I would definitely email. :)

Vivian_Le_1L

Hi! Can someone please help me with 6L.5 d? I looked at the solution manual, and it says that the cell is Au(s)|Au³⁺(aq)||Au⁺(aq)|Au(s). How did they get that answer? Like why is there solid Au on both sides?

Vivian_Le_1L

0th order: [A] vs time (decreasing linear)
1st order: ln[A] vs time (decreasing linear)
2nd order: 1/[A] vs time (increasing linear)

I would look back at Lavelle's lecture. He draws them out on the board and explains them.

Vivian_Le_1L

You can determine k depending on the question. For instance, you can calculate it if you are given multiple rates with concentrations and initial rates. You can also figure out by looking at a graph. I recommend checking out some week 9 worksheets from the UA sessions. They were really helpful with ...

Vivian_Le_1L

Someone already said what the units are above, but you can also figure it out by writing out the equation and cancelling out the units. Reaction rate = Molarity/time Units for k: 0th order: rate = k[A] 0 -> M/s 1st order: rate = k[A] 1 -> rate/[A] = k -> (M/s)/M -> 1/s 2nd order: rate = k[A] 2 -> ra...

Vivian_Le_1L

I didn't have Lavelle for 14A but I really enjoyed learning about Lewis structures and molecular structures. Brought back a lot memories of chem in high school. :)

Vivian_Le_1L

Remember that the units are always concentration per time. Lucy is right when she said that zero order is generally M/s, 1st order is 1/s and 2nd order is 1/M*s, but I would say the best thing to do is just write it out and cancel them out manually if you can't tell.

Vivian_Le_1L

E naught is zero, because at standard condition, the concentrations are equal in the cell.

Vivian_Le_1L

Yes, I'm pretty sure the standard potentials and reaction or at least enough information for us to write out the reaction will be provided for us.

Vivian_Le_1L

Yes, unless otherwise stated, you include the phases. I spent 30 mins on a problem because I was only missing the phases.

Vivian_Le_1L

You add H2O to balance oxygen atoms, so you add it to the side with less oxygen atoms.

Vivian_Le_1L

Usually when a glitch occurs, I either refresh the page, log out and log back in, or change browsers. One of them usually works for me.

Vivian_Le_1L

Probably not the most helpful, but I always thought of the opposites. Oxidizing agents are the things getting reduced and reducing agents are the things that are getting oxidized.

Vivian_Le_1L

In an isothermal process, temperature is constant, so the heat absorbed by the gas equals the work done by the ideal gas on its surroundings. Thus, q=-w and by the equation ΔU = q+w , the net change in the internal energy is 0.

Vivian_Le_1L

Delta G naught is the change in Gibbs free energy at standard conditions (1 atm and 25 degrees Celsius/298.15 K) , whereas Delta G is the change at a specific condition.

Vivian_Le_1L

If Q<K, there are more reactants than products. The formation of products is favored in the forward reaction, because there is more reactants to make products. The opposite is also true. If Q > K, there are more products than reactants. The formation of products is favored in the reverse reaction (f...

Vivian_Le_1L

A closed system is not necessarily insulated, but rather sealed. As a result, matter cannot be transferred, but energy can. An example would be an ice back and how the contents inside sealed within, but the heat between body and ice pack are still being transferred between one another.

Vivian_Le_1L

Kaleb Tuliau 3E wrote:Is it necessary to remember the change of G values of each bond ?

If you are referring to delta G of each compound in a reaction, then I do not think so. It will probably be provided for us in a table or something like that.

Vivian_Le_1L

When ∆G < 0 (negative) the forward reaction is spontaneous. Products are favored.
When ∆G > 0 (positive), the forward reaction is non spontaneous (reverse reaction spontaneous). Reactants are favored.

Vivian_Le_1L

The more negative the delta G, the larger your K value will be. A negative delta G means that the reaction is spontaneous, which favors the formation of products. More products equal a larger K value.

Vivian_Le_1L

Where ∆G is the difference in the energy between reactants and products. ∆G° is at standard conditions (1 atm and 25 degrees Celsius). ∆G° is always the same because it is referring to when the reactants/products are at standard temperature/pressure. As the rxn goes towards equilibrium, ∆G changes b...

Vivian_Le_1L

To figure out which R value to use, you pretty much look at the units involved. See which ones you want to match up/cancel out.

Vivian_Le_1L

Yes, combustion does require energy to break bonds, however, the energy released to form the new bonds is greater than the energy taken in. Thus, the reaction is overall releasing energy and exothermic.

Vivian_Le_1L

q and delta H are not interchangeable unless they are under constant pressure. When they are under constant pressure, q and delta H are equal to each other.

Vivian_Le_1L

Endothermic reactions will always have a positive delta H, because they are taking in heat/energy. Exothermic reactions will always have a negative delta H, because they are releasing heat/energy.

Vivian_Le_1L

A phase change is when a substance changes from one state of matter to another. i.e. solid -> liquid (melting), liquid -> gas (vaporization), gas -> liquid (condensation), liquid -> solid (freezing), solid -> gas (sublimation), gas ->solid (deposition).

Vivian_Le_1L

Yes! Both vapor and gas are the same and interchangeable. :)

Vivian_Le_1L

Hi! It seems like other people already gave you the process on how to solve it, but something to also notice are the phases! HCl is both an aqueous solution and gas here, so you have to make sure you are cancelling out the ones with the same phases. I had some difficulty on this question earlier bec...

Vivian_Le_1L

Dr. Lavelle said that he's going to be going out of order, so he'll probably go over the skipped material but later on. I don't think you should worry too much. :)

Vivian_Le_1L

Hi! I actually have a similar problem. I'm not sure if I should take chem 14BL next quarter with 14C or take 14BL and 14CL during the summer. Does anyone have any advice? Thanks :)

Vivian_Le_1L

The K of the reverse reaction is the inverse of the forward reaction.

A + B <-> C
Forward reaction: K = [C] / [A][B]
Reverse Reaction: K = [A][B] / [C] = 1/K

Vivian_Le_1L

Yes, Kp only applies to partial pressure of gases, while Kc can have concentrations of both gases and aqueous solutions.

Vivian_Le_1L

It's better to check with % ionization. If the % ionization is greater than 5% then you can not approximate even if your K is less than 10^-3.

Vivian_Le_1L

You can approximate when your K value is less than 10^-4. We can assume that x is small enough that we can ignore -x. Remember that this does not mean we can ignore x^2 (I'm just adding this bit b/c someone asked about this on another post). The approximation can be checked by finding the % ionizati...

Vivian_Le_1L

I began by writing out the equation and then made an ice box. I wrote out the Ka expression and solved for x using the quadratic formula. The % ionization is higher than 5%, so you can't approximate for this problem. The value that you find for x is also equal to [H+]. To find the % ionization, divi...

Vivian_Le_1L

Solids and liquids are omitted from the equilibrium constant, because they have a constant concentration. They don't make a difference in the expression, and thus omitted.

Vivian_Le_1L

Hi!

We can use the ideal gas law when we are given values for pressure, volume, concentration, and temp except for one. You can use it to solve for the missing variable. For example, in some of the problems we've done, we've used it to convert from concentration to pressure and vice versa.

Vivian_Le_1L

Pretty sure that Sapling is mandatory, and will actually be collected midnight of the following Sunday, however, is this the only "homework" due?? Yes, I believe Sapling is the only mandatory homework. Professor Lavelle gives us textbook problems as well but those problems are not graded....

Vivian_Le_1L

The K of the reverse reaction would be the inverse. 1/K or K^-1.
EX. [A] + [B] <-> [C]
K_FORWARD = [C] / [A][B]
K_REVERSE =[A][B] / [C] , which is the reciprocal/inverse of the forward reaction.

Vivian_Le_1L

[H2O] is in excess. Because there is a lot of H2O a change in concentration would have minimal effect, and thus it is negligible.

Vivian_Le_1L

Why should you go drinking with neutrons?

Because wherever they go, there's no charge!

Vivian_Le_1L

I love watching Disney movies, especially Mulan, High School Musical, and The Parent Trap. I just love watching these movies so much and find them very comforting. I lowkey also have the entire script for these movies memorized haha. That's literally how much I love watching them. :)

Vivian_Le_1L

The correct answer would be A, because reactions never stop, but they do reach equilibrium when the concentrations of the products and reactants don't change. In order for this to happen, the forward and reverse reaction rates must be the same so there is no net change in the concentrations of reac...

Vivian_Le_1L

Hi!
Yeah you wouldn't need to convert since they are asking for molar concentration and the values you're given are already in concentration (mol/L). If they asked for/given Kp or partial pressures, then you would need to convert using PV=nRT.

Vivian_Le_1L

In terms of steps, I believe it's the same K = [product]/[reactant], but Kc uses concentration and Kp uses partial pressure. You can use PV=nRT to convert concentration to pressure and vice versa. Also, Kp is only for gases, while Kc is for gases and aqueous solutions. I think the values will be dif...

Search found 53 matches