CHEMISTRY COMMUNITY

Levon Grigoryan

It's due today MARCH 14th 12pm and you need 50 posts/replies. However the points for me are glitching. It says I have 56 points then I refresh it and it says 52. (Keep in mind I did not have Lavelle for my first part of Chem so mine is 50, instead of 100 If you took him 14A).

Levon Grigoryan

I honestly didn't think this final was as hard as last quarter's final. A lot of it was plug and chug if you knew what you were doing; the conceptual weren't that hard either. I would say this test is really fair. As for my preferences, I would say online tests are better since they're multiple cho...

Levon Grigoryan

Constance Newell wrote:The questions seemed much more straight forward than the finals

lool.

Levon Grigoryan

Jacquelyn Challis 2B wrote:I'm just praying for a passing grade at this point:) I'm really hoping in person classes resume soon because I don't think I'm learning as well online.

You will pass ! Good luck

Levon Grigoryan

In thermodynamics, entropy contains two conceptually of entropy: a Thermal entropy, STherm = ∫ (Cp / T) dT, due to thermally induced motion of particles, and Residual entropy, S0 due to the arrangement of the particles in a crystal lattice. Though you just need to worry about the first one for now. ...

Levon Grigoryan

How did you guys perform on the final? What was easier and how was it (difficulty-wise) compared to the midterms? For me the final was a little bit simpler than the Midterms especially the first one. And finally, how do you guys feel about remote learning Chemestry? do you guys prefer in-person lear...

Levon Grigoryan

Yes if not given assume room temperature at 25*C, and I think Professor Lavelle mentions that every lecture when temp is not specified.

Hope this helps.

Levon Grigoryan

By upcoming fall classes should open up (in person) or at least that's what I have been told, but in my opinion, this remote learning, though convenient, does not work. Its very difficult to stay focused at home, or stare at a computer screen for hours upon hours every week. This is not good. Well, ...

Levon Grigoryan

Cp = Cv + R, and the R = 8.314 J/K/mol because it is a constant. So If you have one of the other ones Cp or Cv you can easily solve for x to find the other.

Hope this helps.

Levon Grigoryan

Q = [B]/[A]. K = [B]equalibrium/[A]equalibrium

This is the simple way I remember it, so the wording does not get confusing. I think this is more simple.

Levon Grigoryan

The second one is wrong as it should be what I wrote below:
ClO3- + 6e- + 3H2O → Cl- + 6OH-

Hope this helps you just forgot the H2O.

Levon Grigoryan

Hey,
I suggest you not worry about it, as we usually tend to forget that we took a test. And at this point, there is no way to go back. So just keep yourself busy and stress less, because at the end of the day, it's just one class. Stay Safe!

Levon Grigoryan

The purpose of the salt bridge is to act as a source of spectator ions that can migrate into each of the half cells to preserve neutrality. Any charge buildup in the solutions of the two half cells is known as a junction potential.

Levon Grigoryan

This is great lol. Thank You Dr. Lavelle for making chemistry good chemistry.

Levon Grigoryan

This is just something I need to release out of my system as a student during these terrible times. I am so distracted and unable to focus on academics with everything that is going on around me. Some of my neighbors got arrested yesterday for posting slander against the military (Myanmar). And yes...

Levon Grigoryan

The Umbrella Academy, Rick and Morty, Family Guy, But movies I just watched recently some good ones, The Raid (2011), 2001 Space Oddessey, THe Grant Budapest Hotel and many more, movies get more enjoyable during this Pandemic times.

Levon Grigoryan

Why did the Noble Gas cry? Because all his friends ArGon.

Levon Grigoryan

What kind of fish is made of only 2 sodium atoms? .............................. 2Na

Levon Grigoryan

Valerie Tran 2B wrote:What chemistry classes are you guys taking next quarter? Are you moving to the 20-series or starting O-Chem or anything else? Let me know!

No Spaceeeeeeeeeeeee!

Levon Grigoryan

[quote="Mahi Kabra 2F"]Maybe you accidentally used ln instead of log because both are accessed through the same button. I think a common mistake is also using the subtraction sign instead of the negative sign.[/quote I know it is doing the INverse instead of the log. But it says log I pres...

Levon Grigoryan

Has anyone heard anything about getting off the 14CL waitlist? Im one of the last positions but if I dont get off of it I won't be taking enough credits so I was hoping if anyone had advice/has been in a similar situation/knows anything about the waitlist for that class This class is very hard to g...

Levon Grigoryan

Textbook Problems are essential, but what also helps is printing out tests from the previous years and doing them, maybe time yourself and try to be fast and efficient. Maybe even rewatch lectures on topics you are struggling with. The final will be easier in my opinion because we have a longer time...

Levon Grigoryan

#Part 5: The generic rate law is: rate=k [A]^a [B]^b [C]^c k is the rate constant. [A], [B], and [C] are the initial concentrations of the reactants. a, b, and c are the orders of the reactants (A, B, and C). You found the order of the reactant A in part 1: 1st order --> a = 1 You found the order o...

Levon Grigoryan

DO NOT STRESS. This is a 4 unit class and a C is not that bad. And the GPA will not change a lot. And for you to retake a class you will need a D or lower. I suggest you don't retake it and focus on the future. And it's Covid I'm sure you can mention the low grade or grades in your Personal statemen...

Levon Grigoryan

Each Week we should have posted 5. So 5x10 for (Week 10) We would end with 50 posts for a 100%. Hope this helps!

Levon Grigoryan

I have been stuck at this problem for a while now. Thank you for the explanation.

Levon Grigoryan

For this problem, we do not look at the coefficients to find the order of the reaction.

Levon Grigoryan

Part 5 isn't asking for a numerical value. You use the order for each reactant (found in parts 1,2,3) to find the rate law for this reaction: rate = k [A]^n [B]^m [C]^l. (A zero-order reactant just becomes a 1 in the rate law.) Using this equation, you can use the rate and concentrations from any o...

Levon Grigoryan

At constant volume, the heat of combustion of a particular compound, compound A, is −3800.0 kJ/mol. When 1.127 g of compound A (molar mass =115.31 g/mol) is burned in a bomb calorimeter, the temperature of the calorimeter (including its contents) rose by 4.175 ∘C. What is the heat capacity (calorim...

Levon Grigoryan

For me, I watch different videos online alongside Professor Lavelles lectures to understand the types of problems Im solving. If you watch different people explain the same concept, it will eventually kick in. Also, struggling is key, in my opinion. Don't look at how to solve the problem, unless you...

Levon Grigoryan

dont forget however, about the (-) qlost =qabsorbed that the negative represents the heat lost. Then you have your q=m*c*ΔT. (for both sides).

Levon Grigoryan

This is because one degree unit on the Celsius scale is equivalent to one degree unit on the Kelvin scale. So, as long as all your temperatures are in Celsius or all your temperatures are in Kelvin, it doesn't matter which you use. Good point lol. As long as the answer is in one or the other, the a...

Levon Grigoryan

Good question. However, you should see what the textbook questions use. Because I would think professor Lavelle would want us to go off the textbook.

Levon Grigoryan

If I remember correctly week #4 Monday and then some Wednesday. I'm not sure which minute into the exam exactly, but rewatching the video could only help (plus you'll find your answer to the question).

Levon Grigoryan

http://www2.ucdsb.on.ca/tiss/stretton/C ... thal10.htm

Hope this helps. Good Luck!

Levon Grigoryan

a) (1.25mol S8) * (358.8 kJ/1mol S8) = 448.5 kJ b) (197g C) * (1mol C/12.01g C) * (358kJ/4 mol C) = 1471.35 kJ c) (415 kJ/358.8kJ) = (x mol CS2/4mol CS2); x = 4.63mol CS2 The question for the last partt asks for mass of CS2. So the answer needs to be in grams. Just multiply the moles by the grams o...

Levon Grigoryan

What helps is actually starting to write the reaction down before you actually start doing anything. So you have the products and reactants right there in front of you. NH3 and H3O and NH4Cl. So the ice box making becomes easier.

Levon Grigoryan

Hi! When the pH > pKa, the predominant species is charged because the environment around it is more basic (the pH is higher) than the species, so the acid will dissociate and become ionized to make the environment more acidic. When the pH < pKa, the predominant species is neutral because the enviro...

Levon Grigoryan

Also remember that Kw= Ka x Kb
So if Kw is always 1.0 x 10^-14 you can find out the value for Ka or Kb if one of the values is given. For example if Kb is 1.8 x 10^-3 to find Ka you do Kw/Kb (Ka = Kw/Kb). So 1.0 x 10^-14 / 1.8 x 10^-3 = Ka then you can start making your ice table.

Levon Grigoryan

you can always assume and instead of solving the quadratic formula ignore the x for the B and solve the equation and squareroot it to get rid of the x^2. When you get the value of the x and divide it by the initial concentration. (keep in mind the 5 percent rule). So if the value less than 5% keep g...

Levon Grigoryan

after the quadratic equation you get the value of x. Then you take (Ch3CH(OH)COOH) minus CH3CH(OH)COO-) to find the value of (H+). to find the pH you take the -log) of H+ which gives you the value of the pH. And if you have the pH number, you can easily find the pOH which will be 14 - pH.

Levon Grigoryan

To make sure the minor sig fig errors don't occur always put the same number of digits as the other given numbers so instead of 0.001 you would match (or as close as possible) the digits with the previous number. Making your answer 0.001112 and not 0.001

Levon Grigoryan

For the problems we have done, the math is pretty straight forward, however one thing I cannot get right on my calculator is the -log) for a given number on my (Ti-36x Pro). Like I know what to press but the answer never comes out to be correct. I plug in the same number on an online calculator and ...

Levon Grigoryan

I would first start with making an ICE chart and solving for the initial molarity of 2SO3 by dividing the given moles by the given volume. Then you can start filling out your ice chart. The question gives you the final moles and by dividing that by the 3 L, you get the change in molarity/x. With th...

Levon Grigoryan

Talia Leano 2H wrote:When using the quadratic equation to solve for x in ICE table problems how do you know which answer will be extraneous?

Usually, you eliminate the negative answer. but if both are positive Im still unsure, however, my educated guesses have been correct so far.

Levon Grigoryan

Audra Mcleod 3G wrote:Hello!
When both answers for your quadratic equation are positive, you pick the number that is less than the initial concentrations you are given.

I was using this method but was not sure if I was 100 percent correct. Thank you for conforming.

Levon Grigoryan

the ice box is also new to me and what I found the most useful is treating the Initial and the Change as two things being added to each other to result in the equilibrium so let's say: N2 I 0.003 C +x ---------- E 0.003+x this really doesn't make sense as I typed it out. But it helped me to visualiz...

Levon Grigoryan

yes and remember:

pKA + pKB = pKw = -log 10^-14 = -(- 14) and two negatives make a positive so you get 14 at 25 degrees C.

Levon Grigoryan

How do we find the difference in molar concentration using molar ratio? I know he did something with it in the third module, but is there a rule that explains how to convert the molar ratios in the empirical formula to find the difference? In the ICE box, the molar ratio ends up being the ratio of ...

Levon Grigoryan

At equilibrium, the concentrations in this system were found to be [N2]=[O2]=0.200 M and [NO]=0.600 M. N2(g)+O2(g)↽−−⇀2NO(g) If more NO is added, bringing its concentration to 0.900 M, what will the final concentration of NO be after equilibrium is re‑established? I keep getting 0.75 my K is 9 and ...

Levon Grigoryan

If someone could help me with this one I would be so appreciative! I have tried so many times and can't figure out what I am doing wrong so if you could use my numbers that would be great!! at the end to find the answer just take the final 0.800 and subtract it 2x the number you got 0.881 and that ...

Levon Grigoryan

The homework is due on the 17th, hope this helps! Hi, quick question. So does that mean that today (Sunday, Jan 10) is considered to be Sunday of Week 1 and not Sunday of Week 2? Yes, today is Week 1. Hopefully, this is true. Because some Professors say due Sunday Week 2 but mean the end of Week 2 ...

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