CHEMISTRY COMMUNITY

Joslyn_Santana_2B

W2010 Q4B

1.) How do you know "the cell emf was +0.060V." means Ecell and not E*cell?

2.) How do you know n=1? I thought n=2 from Q4A, which was the redox reaction where 2 electrons were transferred.

Joslyn_Santana_2B

W 2011 Q2

Why is 3H2 ignored in the 1st rxn? Why is H2 ignored in the 2nd rxn?
I thought it was because of a phase difference in the 1st one, but in the 2nd rxn there is no phase difference and it's still ignored.

Joslyn_Santana_2B

I was wondering why it is correct, when time is supposed to be in seconds? I got to completely different answers when I converted to seconds as opposed to leaving it in minutes.

Joslyn_Santana_2B

Can you give a molecular formula, or example?

Joslyn_Santana_2B

Yes, Iso- is included for alphabetical order, as is Neo-. Di- is not.

Joslyn_Santana_2B

Since they are attached, you can imagine it based on how many carbons and hydrogens there are. If that makes sense.

Joslyn_Santana_2B

Is it a rule that equatorial is prioritized over trans when choosing the most stable conformation for cyclohexanes?
I had made it trans, making the Chloro equatorial down, and the methyl axial up.

Joslyn_Santana_2B

Step 1: Where is Hydrogen that broke off from the H30? I thought the double bond was attacking it, causing it to break off.

Step 2: How are there 2 H20 molecules? How is there a product of H+/H30+?

Joslyn_Santana_2B

Dear Dr. Lavelle, Thank you for being the most organized professor I've had thus far. I remember 14A was one of my first classes here, and I was relieved to have all the topics available on your website to practice in advance. During the quarter, the abundance of resources you offered were also very...

Joslyn_Santana_2B

1.) When a TA went over this at the review session, they said this question has SN1 and SN2 reactions throughout the steps. Is a question like this one possible to appear on the Final? The whole reaction has 4 steps, which confuses me since we have only covered SN2 and Electrophilic Addition Reactio...

Joslyn_Santana_2B

I was wondering how the Arrhenius Equation would be changed algebraically with the given equation on the formula sheet to the one in the reader?

Joslyn_Santana_2B

Functional group gets priority over the double/triple bonds.

Joslyn_Santana_2B

Leo_Navejas_3B wrote:For substituents do we use common or systematic naming??

I was told common and systematic naming are the same thing.

Joslyn_Santana_2B

What counts when using the alphabetical reference when naming?

I thought Neo- and Iso- counted, while Tert- didn't? Or is it the opposite? Is there a reason for it?

Thanks in advance.

Joslyn_Santana_2B

I wouldn't look at that as a definite rule though.
For example, Exercise 4.1 part d is F by itself, and it is an electrophile.

Joslyn_Santana_2B

Is it wrong if I wrote the condensed formula with the CH3 methyl next to the CH instead of doubling the end?

Joslyn_Santana_2B

What is an example where the general rule does not apply?

Thank you in advance.

Joslyn_Santana_2B

How do you know how many steps are going to be in the reaction mechanism? Or is it just memorizing how many for each type of mechanism?

Joslyn_Santana_2B

Yes, but if there are no labels/values given then there is no other way to know? Unless you're given that information, or a rxn.

Joslyn_Santana_2B

I was wondering why the reader has that the y-intercept starts at the top for 1st Order and the y-int starts a bit below the top for 0 order, but the textbook has 1st and 0 order y-intercepts starting at the same point. The only difference is of course in the variables/values. How would we know the ...

Joslyn_Santana_2B

Starting from M/s you just then divide my M continuously to get the next order units.

Joslyn_Santana_2B

The bar indicates a separate reaction/solution. A TA said the comma means it's in the same solution.
Hope that helps.

Joslyn_Santana_2B

1. Why does solution's manual use positive RTlnQ instead of negative? How do you know which equations to use?

2. The solution states, "Because deltaG is positive, the reaction will be spontaneous to produce I_2. I thought positive deltaG meant non-spontaneous ?

Joslyn_Santana_2B

Why when calculating entropy with a change in temperature are there instances where the equation used is nRln(T2/T1) and then others where we use nCpln(T2/T1)? Does the question have to explicitly say that the rxn is at constant p or v? If it doesn't say then we just assume we can use nRln(T2/T1) to...

Joslyn_Santana_2B

Nvm, someone told me that it was a typo.

Joslyn_Santana_2B

Hi,

For the explanation of the sign of work in this problem has me confused from the solution manual.

Is deltaE the same as deltaU, and that's why q & w switch off signs to balance the internal energy?

Joslyn_Santana_2B

Will we be given the conversion factor from torr to atm on the formula sheet?

Joslyn_Santana_2B

Hi,

I am confused, since it initially states the pump depresses the air, but for part a it says to find work if it is compressed. Are we to assume that it was compressed the same distance that it was initially depressed?

Thank you in advance.

Joslyn_Santana_2B

I am interested as well! My e-mai is jospamsantana@gmail.com

Joslyn_Santana_2B

I think it refers to the work, and which equation you would use in your calculations. You would use W=-nRTln(V2/V1).
It also means that deltaU is 0

Joslyn_Santana_2B

Is there a copy of the solutions manual on reserve at any of the libraries, if so which library?

Thank you in advance.

Joslyn_Santana_2B

It is right after Example 8.1 under "Thinking Point:". I do not have a hard copy of the text, but it says it's page 407 of 1129, but page 265 on the pdf. Hope this helps.

Joslyn_Santana_2B

Does anyone know why the most stable lewis structure for NO₂ has charges on N and one of the O's, when there is a structure where all the FC's can be 0?

Joslyn_Santana_2B

It is actually if it's exponent is less than or EQUAL TO -4.

Ex: K_a= 3e^(-4), you can use the short cut to find x.

Joslyn_Santana_2B

I usually look at all the dipole moments in the molecule's VESPR model, which shows visually if there are any dipole moments that cancel. If they don't cancel, then it will be polar.

Joslyn_Santana_2B

I know that for EDTA it binds 4 times because it has 4 ends where the oxygens are bent, which makes it easier for chelating to occur.

Joslyn_Santana_2B

You use Bis-, Tris-, Tetrakis-, and Pentakis- for Polydentate ligands

Joslyn_Santana_2B

Hi,

Here are some notes I took of a TA's explanation of visualizing the Pi bonds. Hope this helps!

Joslyn_Santana_2B

On the sample midterms, it gives the solution in both versions of calculating. Also, my PLF said you can calculate it either way.

Joslyn_Santana_2B

Here is an example of Xe breaking the octet rule.

Joslyn_Santana_2B

Hi, Does anyone know why for Xenon (Xe) can break the octet guideline?

I wrote out the electron configuration for it thinking it would help me see it visually, but all the d,s, and p orbitals are full. I am not seeing why it can break the octet rule.

Joslyn_Santana_2B

Will we have to know how to write electron configurations for Quiz 1?

I am confused on that topic, and the connections of the diagrams to the atom's structure.

Joslyn_Santana_2B

Oh wow, this whole time i thought Rh was R with a subscript of h. Thank you!

I got how you got energy and combined the two different energy levels to get the change in energy, but I don't get how -7.5539x10^(-20) as the denominator gives you a positive # under the square root.

Joslyn_Santana_2B

Also, how do you know which equation to use? I am confused on the solutions explanation of how they got -2.178x10^(-18) J (Z^2/n^2). At first I was using the equation set up to find frequency, but the realized that wasn't the correct one. Additionally, why is Rh (Rydberg's constant) 3.28984x10^15 on...

Joslyn_Santana_2B

How did you get rid of the negative at the end before square rooting?

Joslyn_Santana_2B

For Quiz 1, then it would not be similar to all the homework questions only certain ones?

Since, in E9 it states: "Epsom salts consist of magnesium sulfate heptahydrate. Write its formula."

Joslyn_Santana_2B

I'm interested!

Joslyn_Santana_2B

Just realized this was covered in the video module.
Sorry about that, and thank you for taking your time with the explanation!

Joslyn_Santana_2B

Are we allowed to screenshot a question from the assessment to post on our question, and use for reference/clarity?

Joslyn_Santana_2B

For question #9 in the assessment states: "8.00g of Vitamin C is analyzed and the results are: C 3.27g, H 0.36g, O 4.37g. Using mass spectrometry its molar mass is determined to be 176.14g*mol^(-1). What is the molecular formula for Vitamin C?" I got lost after you find the ratio for the e...

Joslyn_Santana_2B

In the Pre-Assessment the question is #8, and states: "Xylitol, a sugar subsitute, has a mass composition of C 39.43%, O 52.58%, H 7.88%, and a molar mass of 152.15 g*mol^(-1). What is its molecular formula? " In the answers all the Hydrogens were not multiples of 5, which was the number I...

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