CHEMISTRY COMMUNITY

Krikor_Kevranian_1F

Hi, I talked to several TAs and UAs and they all mentioned that after we get our final grades back, Professor Lavelle will see the averages and put a curve on our final grades if it is warranted. Although we haven't heard anything from Professor Lavelle himself so I'm not exactly sure either. Additi...

Krikor_Kevranian_1F

To add to the other post that covered the answer. A good analogy to help with your question is thinking of a freeway with hundreds of cars in one line. If the slow step is the very first car in that one line and how they are below or maintaining the speed limit. It will slow down all of the other ca...

Krikor_Kevranian_1F

Through the different UA and TA sessions that I have gone to. They always say that an intermediate is thought of as being formed in the product and then used up in another step reactant. The catalyst was used up in the reactant and then formed in the product of another step.

Krikor_Kevranian_1F

To add to the other posts that did a good job of explaining why the catalyst is not consumed in the course of a reaction. A simple way of thinking about it is like having a cookie jar and once you take out a cookie for a reaction then it will get replenished through the product of another reaction t...

Krikor_Kevranian_1F

I know for the most part it should be stated in the given problem. Although earlier today in Gabriel Nitro's zoom he did show us how to tell which one was the slow/slowest step. This was by looking at the activation energy and if one of the reactions was much greater than the rest(takes a long time ...

Krikor_Kevranian_1F

To add to what Patrick said I remember in Gabriel Nitro's zoom, he mostly rounded for each number before continuing. Although he did mention that it would probably be best to wait until the end to round to get a more accurate value for the question. On the other hand, he also said that when you solv...

Krikor_Kevranian_1F

I'm wondering where I went wrong with trying to calculate the constant rate of K and how I do the last part of the question as well. I tried a couple of different ways to solve it but it doesn't seem to be correct. Any help would be appreciated. Screen Shot 2023-03-17 at 9.16.28 PM.png Screen Shot 2...

Krikor_Kevranian_1F

I'm wondering where I went wrong with the last part of this question. I tried a couple of different ways to solve it but it doesn't seem to be correct. Any help would be appreciated.

Krikor_Kevranian_1F

While you are correct with n referring to the moles, it refers to the moles of the electrons transfer instead of the moles of a reaction thus this wouldn't be canceled out the units. So you are left with J/mol as the final units.

Krikor_Kevranian_1F

Yes, I do believe that the anode is the lower concentration of the two. As for the Nernst equation, it is anode/cathode.

Krikor_Kevranian_1F

From what we have seen from our homework, I believe that it should indicate whether or not it is in a basic or acidic solution.

Krikor_Kevranian_1F

For this question, I was first confused as well. What I did was started with the Pb(s) which is on the anode side then the half-reaction is Pbcl2(s) which should be on the anode side too. From there I looked at AgCl(s) and the half-reaction for that is Ag(s) which is on the cathode side. But you can...

Krikor_Kevranian_1F

I've attached an image of my balanced equation. From achieve it said that I balanced the oxygen and hydrogen but I didn't balance the electron transfer correctly. I have tried everything to help balance the electron transfer but I still can't figure it out. So I was wondering where am I going wrong ...

Krikor_Kevranian_1F

For cell diagrams problems I understand that for the cathode side, you have to put Pt(s) for the electrode only when there are no solid metals on that and vice versa for the anode but why do we specifically use Pt(s) instead of something else?

Krikor_Kevranian_1F

Why don't we use w=-P*deltaV for path A? I believe we don't use w=-P*deltaV for path A because it doesn't mention anything about external pressure. It does state the volume at which it expanding but for path B it specifically states external pressure which is when we would use the equation w=-P*del...

Krikor_Kevranian_1F

You would first need to use the equation PV = nRT with the initial volume and R being 0.08206 because it is in units of L atm/mol K. Then plug the moles (n) into the work equation to get your answer.

Krikor_Kevranian_1F

You would have to use the initial volume in the PV=nRT as it is asking for the volume at which we know the initial moles of

Krikor_Kevranian_1F

When Qp is under constant pressure and when the system has no work done. Delta H would be the same as Qp

Krikor_Kevranian_1F

Enthalpy is the total amount of energy a system whereas entropy is the measurement of the change in enthalpy or temperature.

Krikor_Kevranian_1F

When the reaction is non-spontaneous this will result in Gibbs free energy is positive. Thus the entropy is negative and the enthalpy is positive. If the reaction is positive then it will be negative with the entropy being positive and the enthalpy being negative

Krikor_Kevranian_1F

I believe that those types of conversions are going to be on the Constants and Formula sheet that we are allowed to have with us for the exams.

Krikor_Kevranian_1F

For w=∆nRT, the T should be delta T and to find that you need to first find the final temperature and then subtract that from the initial temperature. For question 17 they already gave you delta T which is 18.9 K.

Krikor_Kevranian_1F

In the case that 350 J of work is done by the system. This would be added to U because the energy is being added.

Krikor_Kevranian_1F

From my understanding of what's in an instant ice pack, it has ammonium-nitrate fertilizer in some sort of concealed part in the pack with the water. When you squeeze the pack to make it cold, the water and the ammonium-nitrate fertilizer mix together causing the mixture to become an endothermic rea...

Krikor_Kevranian_1F

"Do work on the surroundings" in this context would be an Exothermic reaction due to the fact that heat is being expelled into the surroundings.

Krikor_Kevranian_1F

Isabella is 100% correct in that the whole system would increase. Both the water and the ice will begin to heat up but it may take a few degrees more for the ice to melt while in the water completely.

Krikor_Kevranian_1F

If you scroll down to the end of the table of contents in the textbook, there is a section called "Back Matter." The "odd-numbered exercises" tab should have the answer to every odd-numbered question in the book. I had the exact same question. Thank you so much for answering thi...

Krikor_Kevranian_1F

I'm not 100% confident on this, but I figure I'll try to do it and explain because I need more practice. You want to start by converting the pH given to pOH. pOH = 14 - 9.325 = 4.675 Next, use the pOH to determine the concentrations of the protonated amine BH+ and OH-. [BH+] = [OH-] = 10^-pOH = 10^...

Krikor_Kevranian_1F

For homework questions 7 and 8. After you get your x value and use -log to find the pOH you can simplify the pH+poH=14 where you can use subtraction to get the pH of the solution. Hope this helps!

Krikor_Kevranian_1F

I believe the issue is that for this equation x^2 - 0.00487x + 9.5452 * 10^-4 = 0 you have the plus and minus in the opposite positions. It should be x^2 + 0.00487x - 9.5452 * 10^-4 = 0 instead and that would work.

Krikor_Kevranian_1F

For this type of question, It is simply where you can choose any of the equations that were given. The ones that I used were 3H2(g)+3I2(g) ↽−−⇀6HI(g) and 2NH3(g)−⇀N2(g)+3H2(g). They give you the K values for them so I balanced the equations to get 2NH3(g)+3I2(g) ↽−−−⇀N2(g)+6HI(g). And so the k value...

Krikor_Kevranian_1F

For this question, you don't need to plug x into -log(H3O+) and get 1.602. Instead, take your x value of 0.0025 and divide it by 0.137 M which is your percent ionization solution. As well as multiply that by 100% to get the percentage. So (0.0025/0.137)*100% will get you the percent ionization. Hope...

Krikor_Kevranian_1F

I would say that looking at youtube videos or channels will greatly help. I know that I used to watch videos on subjects learned in 14A to have a deeper understanding of what was going on. As well as if I was confused about something that I could watch a video on quickly. I would suggest "Ninja...

Krikor_Kevranian_1F

Definitely start studying a while before the exams, and do as many practice problems as you can! Working out problems really helps solidify concepts and makes you prepared. Do not try cramming the night before; it never helps. Exactly. For this type of class doing practice problems will be the only...

Krikor_Kevranian_1F

I got my x value from the quadratic formal but what is the next step to get [NO]final as my answer? Thanks for any and all help.

CHEMISTRY COMMUNITY

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Final Grade Curve

Re: Catalysts and Activation Energy

Re: intermediate versus catalyst

Re: Catalyst Question

Re: How to determine the slow step?

Re: initial rates method

Week 8-10 Assignment Question 7

Week 8-10 Assignment Question 11

Re: Units in Gibbs Equation

Re: Concentration Cell, cathode vs anode

Re: Reaction in basic/acidic solution

Re: Achieve #7

Week 5 and 6 Assignment Question 3 - Where did I go wrong

Cell Diagram

Re: How do you do question 3 on homework 4&5

Re: Achieve Week 5 and 6 Assignment Q 3

Re: Achieve #3

Re: Delta H at constant pressure

Re: Entropy and Enthalpy

Re: Gibbs Free Energy

Re: Unit Conversion for w=-PV Problems

Re: w=∆nRT, use T initial or T final?

Re: Work done by a system

Re: Why are ice packs endothermic?

Re: Week 3 Q3

Re: phase change curve

Re: book answers

Re: achieve assignment, q5

Re: HW 2 Q 7/8

Re: Week 2 Achieve #2

Re: Homework Question #5

Re: Achieve question #2

Re: Rusty on High School Chem [ENDORSED]

Re: Final Jitters

Question 9 on Week 1 HW