CHEMISTRY COMMUNITY

Uyen Trinh 3C

I miss being at school and being surrounded by my supportive friends and other motivated students. Seeing ya'll grind put my [censored] into gear. I had to go get my own bread, watching everyone else getting theirs. Also, studying at home just isn't the same. It doesn't give me as much satisfaction ...

Uyen Trinh 3C

Brian Bui 3H wrote:In this case the prime symbol ( ' ) is just used to distinguish k of the forward reaction vs. k' of the reverse reaction. No relation to derivatives as far as I'm concerned. Hope this helps! :^)

This helps. Thank you. I was also confused.

Uyen Trinh 3C

Intermediates are not included in rate laws.

We're also discussing this in another post if you want to check it out!

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=150&t=77103&sid=974283cc5ce1e457df0f1aa6675dcb50

Uyen Trinh 3C

Intermediates do not appear in the overall reaction because it is the product of one step in the mechanism and a reactant in a subsequent step. Therefore, it should not be included in the rate law, and a substitute expression is needed for the intermediate. Usually, it would appear in other steps of...

Uyen Trinh 3C

The question can seem daunting at first but I assume [A] and [B] as equal 1 and work from there. That way, when they say [A] is halved or tripled, I can just assume 1 * (1/2) = 1/2 or 1 * 3 = 3 and apply what others have mentioned in the comments above.

Uyen Trinh 3C

Hi! This question is a little confusing at first, for sure. This is my work for it. https://mail.google.com/mail/u/0?ui=2&ik=339c078b3b&attid=0.1&permmsgid=msg-a:r1964822708285824246&th=177d26f58ab34ccd&view=fimg&sz=s0-l75-ft&attbid=ANGjdJ-C-KnBctkpeW7CtijY0ePFHtcUYMvRzCn...

Uyen Trinh 3C

Also, I just found this fabulous website that helps you balance Redox reactions.

I hope it helps.

https://www.periodni.com/balancing_redox_equations.php

Uyen Trinh 3C

I found this website that helps you double-check your work and walks you through the steps.

I hope this helps!

https://www.periodni.com/balancing_redox_equations.php

Uyen Trinh 3C

I don't see the harm in posting in Chem 14A. If the content you need to know is from 14A then going straight to the source would be most helpful. Also, I'm seeing how 14A, 14B, and probably 14C, are tying all together more and more now. Such as how in finding oxidation numbers, you need to be famili...

Uyen Trinh 3C

Split the reaction into half-reactions: (1) One involving silver (Ag+ and Ag) and (2) the other involving sulfur (SO32- and SO42-) Balance equation (2) using H2O and H+. Add electrons to the side of H+ so that the charge balances out. Leave it as acidic for now. Add the two half-reaction equations t...

Uyen Trinh 3C

OIL RIG!

That is the best. Oxidation is Losing (of electrons) while Reduction is Gaining (of electrons)

Uyen Trinh 3C

You can refer to this post where we also discuss adiabatic processes.

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=128&t=75500&sid=facb94670fd13b8a06a541aed81a4ee3

Uyen Trinh 3C

favorable or stable or spontaneous all imply the same thing: deltaG < 0 (negative) I agree with Tikva. Additionally, if we think of a spontaneous process as a system that releases free energy (usually as heat) and moves to a lower, more thermodynamically stable energy state, then we can think of wh...

Uyen Trinh 3C

You can refer to this post where we also discuss this problem!

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=139&t=75611&sid=facb94670fd13b8a06a541aed81a4ee3

Uyen Trinh 3C

I've noticed that going to UA sessions really helps me feel confident in my knowledge of all the topics. I call it fun studying because technically you are studying for the final, but you are doing it with others who are also on the same boat.

Uyen Trinh 3C

If you want applicable practice on questions containing adiabatic, Kate had one question involving it in her Week 7 Workshop Midterm Review.

I've attached it and her answers for it.

Hope this helps.

Uyen Trinh 3C

This is slightly out of the scope of Chemistry but I was wondering what you guys do when waiting for your results, especially when you start to second guess what you did and self-doubt kicks in. I'm kind of blanking. I don't remember what I did during the test and feel a little nervous about the res...

Uyen Trinh 3C

Jamie Wang 3C wrote:I drink the same tea while studying and taking the test. It helps calm me down and jog my memory. I also use the same pencil

This is actually super smart. Thank you for this tip. I will try this for the final.

Uyen Trinh 3C

I personally found the test to be a little more difficult than I had anticipated. I was able to do all the problems from workshops and the homework; however, the midterm's problems seemed a little harder. Maybe I was just nervous. Can anyone else relate? I really felt the "Maybe I was just ner...

Uyen Trinh 3C

I find it easiest to write out my units alongside my calculations and then cancel them out as I go. This way I know which units are leftover and which R-value to use. You can search up "stoichiometry" on google and look at the images to see what I mean by writing units alongside calculatio...

Uyen Trinh 3C

Generally, whenever there is ° it means under standard conditions of 1 atm and at 298K.

Similarly, standard Gibbs free energy of reaction (ΔG°) and standard entropy (ΔS°) are given to us in tables that are defines as under standard conditions.

Uyen Trinh 3C

You're describing an isochoric process or as you stated, a constant volume process. The formula for work is w=PΔV, and if there is a constant volume, that means there is ZERO change in volume. Because ΔV = 0 , any P value that you multiply it by is going to give you 0 for work. w=P(0) will always m...

Uyen Trinh 3C

Is the best way to go about these types of problems memorizing the oxidation numbers for some elements? You can definitely just have the Periodic Table by your side so that you don't really have to memorize oxidation numbers. Though through frequent and repetitive practice, it'll probably happen an...

Uyen Trinh 3C

OIL RIG was the best thing that has ever happened to me. Saved my [censored] whenever anxiety and stress kicked in and high cortisol levels diminished my retention and recall skills. :)))

Uyen Trinh 3C

I just had the same question and think I figured it out! If ΔG>0, then the products of the reaction are unstable, while the reactants are stable. If ΔG<0, then the products of the reaction are stable, while the reactants are unstable. be sure to see what the question is referring to (usually it say...

Uyen Trinh 3C

My TA said he discussed it in OH. But mine is all there, I hope yours is back now too.

Uyen Trinh 3C

It depends on what the question is asking for but in most cases it is the equilibrium constant.

Uyen Trinh 3C

I'm taking 14BL this quarter and I'm actually really enjoying it. Taking it online takes away from the hands-on, physical aspect of labs but Dr. Casey is amazing. She creates opportunities for us to learn from our mistakes and has one of the best CCLE file organization systems ever. As someone who g...

Uyen Trinh 3C

Hi you guys, I have the worst online-testing anxiety and was wondering if you guys have any tips on how to reduce this stress. Do you guys meditate before? Read to keep your mind off of the midterm? Eat? Drink? Sleep? I am at the point of considering talking to CAE about possible solutions. I don't ...

Uyen Trinh 3C

I think it is also helpful to know that 298.15K or 25 degrees Celcius is room temperature. That is why it is used as the standard temperature.

Uyen Trinh 3C

If you just want a hint, don't look to the bottom of this post - I attached my work for Sapling #12 that has different values but the same calculation process. How I start any question is by writing down all the values I know, so here that is the temperature change (ΔT), the mass of the compound, it...

Uyen Trinh 3C

Entropy is a measure of randomness within a system. Depending on the structure and components of different compounds, entropy could vary. From the problem, we know residual energy is the entropy of a compound at absolute zero that comes from positional disorder since there is no kinetic energy at T ...

Uyen Trinh 3C

Hi! I started by looking at the information given in the problem and then picking out the formulas I will need. I knew that finding the change in entropy for gas will require me to find ΔS and based on the question the formula needed to take into account a change in temperature. We also have the mol...

Uyen Trinh 3C

Because the volume of the gas remains constant, no work is being done in the first step. Gases do expansion or compression work following the equation: work = -PΔV "When reactions or processes occur in a rigid, sealed container such as a bomb calorimeter and there is no change in volume possibl...

Uyen Trinh 3C

Hi, I'm not sure if you need help with this question anymore, but here I am! What usually helps me is looking at other examples and then following it through step-by-step until I understand what to do and why I do it. My Sapling #18 has different values and different chemical compounds but is asking...

Uyen Trinh 3C

Calculate the concentration of CO (g) in mol per cubic meter at 423K and 0.80 atm assuming only CO (g) is present. https://mail.google.com/mail/u/0?ui=2&ik=339c078b3b&attid=0.2&permmsgid=msg-a:r-8364127856167457617&th=17758c69935382da&view=fimg&sz=s0-l75-ft&attbid=ANGjdJ-...

Uyen Trinh 3C

Only liquid and solids are taken out when calculating K because we cannot measure the molarity of solids and for liquids, the solvent is in excess so change is insignificant.

Uyen Trinh 3C

Hi! I try to think of it when you're changing of units celsius to kelvin. When you have 1 degree Celsius, it would be equal to 274 Kelvin. If you have 2 degrees Celsius, it would be equal to 275 Kelvin. Either way, the difference is just 1. Hope that helps! I think of it in this way too! It may als...

Uyen Trinh 3C

I personally found the test to be a little more difficult than I had anticipated. I was able to do all the problems from workshops and the homework; however, the midterm's problems seemed a little harder. Maybe I was just nervous. Can anyone else relate? I really felt the "Maybe I was just ner...

Uyen Trinh 3C

Whether you have to set up an ICE chart depends on the information the question gives you. If the problem already gives you the equilibrium concentration or partial pressure values of the product and reactants, you can simply plug them into the equilibrium constant ratio... and tadah you get K. Howe...

Uyen Trinh 3C

Okie dokie :))

I hope you have a wonderful three-day weekend. Thank you for all that you do.

Uyen Trinh 3C

I find it really helpful to go online and find examples of similar problems to look at and follow. If I'm feeling snazzy that day I'll go on Youtube to watch video examples, if not I just type in "__topic__ worked examples" and many resources will come up. For this particular Sapling quest...

Uyen Trinh 3C

At equilibrium, Q=K . When the value of Q is not the same as the value of K c , the reaction is not at equilibrium. Additionally, when Q is less than K c , the reaction will shift to form more products to reach equilibrium. Vice versa, when Q is more than K c , the reaction will shift to form more r...

Uyen Trinh 3C

Hi!

I was wondering if there are any arrangements for international students for the two midterms like there is for the final? No problem if there isn't. I just want to be as prepared as I can.

Thank you in advance!

Uyen Trinh 3C

HW question 3 asked to find the concentration of HI at present equilibrium. Although I first solved it using the quadratic equation, Sapling showed us a pretty neat way to do it without the need to use it at all. Here is my working for the question in both ways. I've covered my answer, but I hope th...

Uyen Trinh 3C

I'm also struggling on the application of the quadratic equation. I'm not sure how to use it correctly or when to use it :,) There are a ton of online resources you can look into to help with your application of the quadratic formula, such as: https://chem.libretexts.org/Bookshelves/Physical_and_Th...

Uyen Trinh 3C

I set up an ICE table and then worked it out from there. https://mail.google.com/mail/u/2?ui=2&ik=5138982af3&attid=0.1.1&permmsgid=msg-f:1689128969359873984&th=1770fdd9268457c0&view=fimg&sz=s0-l75-ft&attbid=ANGjdJ9ymWiaCDCDcd6U2GSWj3uzbE_FrRw6MlJrO5byPT1qaQxAgUIyhaCxgBPIC...

Uyen Trinh 3C

What helps me get at these chemical equilibrium problems is handwriting everything out. Here is how I did it as well as the way Sapling teaches us to do it. I erased the answers but left all my workings. I hope this helps. https://mail.google.com/mail/u/2?ui=2&ik=5138982af3&attid=0.1.1&p...

Uyen Trinh 3C

0 Kelvin, which is -273.15° on the Celsius scale, is absolute zero. While the Celcius scale is calibrated in terms of the freezing and boiling points of water, the Kelvin scale is calibrated in terms of energy itself. At absolute zero, the substance has no kinetic energy - the lowest possible temper...

Uyen Trinh 3C

Super interesting read! The covalent H-bond hybrid slightly reminds me of the existence of the intermediate structure rather than resonance structures of benzene and other molecules or ions that share their double or triple bonds. For example, instead of there being one double bond and two single bo...

Uyen Trinh 3C

I just wanted to add that when K is any value in between the chemistry-defined cutoffs of 10³ or 10^-3, neither the reactants nor the products are favored. So we do not have a strong statement on whether the equilibrium favors the right or the left.

Uyen Trinh 3C

Using "shifts" can be misleading as it connotes change. Dr. Lavelle clarifies in Lecture 2 that when given a reaction at a specific temperature at equilibrium, the concentration of reactants and products do not change. Thus, equilibriums do not change. However, if you were to compare this ...

Uyen Trinh 3C

I agree with everyone else. But just wanted to add the reason why we do not include water in a liquid state. As aforementioned by Professor Lavelle, anything in a solid or liquid state should not be included in the K expression. When water is in a liquid state, it is omitted because the change in it...

Uyen Trinh 3C

I'm not sure what specific happy memories I associate with Friends, the tv show, but if I am ever feeling anxious and in need of a quiet night, I turn on Friends. I think the uncertainty of the past year has made me feel really disoriented so it comforts me whenever I revisit any movie or tv show I ...

Uyen Trinh 3C

I noticed how there are assignments in addition to the homework without due dates on Sapling right now such as Math Review; Practice Drawing Molecules; and Chemical Equations Training. I was wondering if these are mandatory or just additional practice. If they are graded, how do we know when they ar...

Uyen Trinh 3C

Professor Lavelle does a really good of explaining why you do this in his first lecture (I think it's 3/4 of the way through the lecture). Because the equilibrium constant is the ratio of the concentration of product to that of reactant, when you "flip" the reaction, you are "flipping...

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