CHEMISTRY COMMUNITY

Yinhan_Liu_1D

It is not methylene because methylene refers to a group in the middle of the carbon chain (-CH2-). The CH3 attached to one of the carbons in the double bond is a substituent by the rule that is discussed in this section, and is therefore called a methyl group. There is no "ethyl" in the n...

Yinhan_Liu_1D

On our intro organ textbook, page 54, at the very top I don't understand why we need to put an "E" in front of the compound name in this molecule. Is it because the geometric isomer (the bond between the third C and the fourth C could be in the other direction)? But if we just write But-2-...

Yinhan_Liu_1D

On our textbook, page16, rule 5: the group that bounds to the second Csp2 is CH2CH3. Why is it Z-1-chloro-2-methyl-1-butene but not Z-1-chloro-2-methylene-1-butene or Z-1-chloro-2-ethyl-1-butene?? If it counts the group that directly bounds to C, it should be "methylene"; if it counts the ...

Yinhan_Liu_1D

I looked at one of the question posted here before, it says it's common name is diisopropyl, is that right? Is there another common name for this?

Will we be asked to name the structure that would be like this (requiring dividing the structure into multiple iso/neo groups)?

Yinhan_Liu_1D

On our green textbook, page 10, the structural formula is given as (CH3)3CCH2CH3.

I am wondering, given the line structure on the side, could the structural formula also be CH3C(CH3)2CH2CH3?

If not, why?

I would appreciate your help.

Yinhan_Liu_1D

#2, it asks us to draw a structure, when we are drawing the line structure, do we specify (draw out) the carbon where the parent chain is branched? Or we just draw a branch?

Yinhan_Liu_1D

On the organic textbook, page 156, when it is discussing the S/R isomers, it mentions the priority in drawing the structure: Nu> CH2CH3>CH3>H.

Where does this come from? Is the priority according to the number of carbon?

I would appreciate your help.

Yinhan_Liu_1D

We know that in this process delU=3/2 nRdelT, isothermal, so that we could use delS=q/T=-W/T=nRln(V2/V1)

But does anybody know why we can't use delS=kB*ln (V2/V1)? It gives us a very small figure, which is not the same as that calculated in nRln(V2/V1)

I would appreciate your help.

Yinhan_Liu_1D

I don't quite understand why we use K=[H+]/[OH-]

Are we using H2O->H+ + OH-? Then why aren't they both in the [product] part?

Or there is another RXN?

Yinhan_Liu_1D

This was a response by Chemmod a couple of years ago: This reaction is the opposite of Problem 13.11d so to make the comparison easier I will flip this reaction (this does not change the chemistry). In that problem you are given the cell diagram to help in the selection and you then solve for the f...

Yinhan_Liu_1D

Hi, dear all, I find it confusing using the equation given in ln and the equation given in log. For example in HW 14:97: If we use ln: lnK=nE/0.02569v = -12 -->K=6.14*10^-6 But if we use log as in the course reader: logK= nE/0.0592=-5.4 --> K= 3.93*10^-6 And by taking the square root of them, I get ...

Yinhan_Liu_1D

Using O2 in the galvanic cell Can anybody tell me what's been reduced and what's being oxidized in this reaction? Since O2 does not appear in the overall reaction, how does the reduction and oxidation happen? I am really confused about this one, so I would really appreciate your help. Same with Ag+ ...

Yinhan_Liu_1D

Hi, all, We mentioned La Chatelier's Principle today. I understand that adding Mn2+ would result in the RXN going to the right (more Al3+ and Mn will be produced). And I kinda understand that adding more "positive charges" to the right means that there will be a higher difference in E. But...

Yinhan_Liu_1D

I didn't quite understand why the definition of S=0 (H+) determines that the aqueous ions has a negative entropy.

Could anyone kindly explain it?

Yinhan_Liu_1D

For part (b), If the expansion is irreversible and w=0 , how could we calculate the entropy change of the system?

Why does it equal to +3.84J/K, the entropy change in the (a)isothermal reversible expansion?

Yinhan_Liu_1D

That could be a possible explanation, but it would best to draw out lewis structures of COF2 and BF3. By drawing out the structures, you can see that the elements can be in different positions, and whichever molecule has the most displacements, it will have higher entropy. So it is because, the mor...

Yinhan_Liu_1D

COF2 will have a higher molar entropy than BF3. They would both be trigonal planar molecules. The answer says that since O and F will disorder the COF2 by occupying the same location. Is my understanding right that the molecule that has a distorted composition will have a higher entropy than the mol...

Yinhan_Liu_1D

Sweet! Thank you.

Yinhan_Liu_1D

Is it combustion?

Is it opposite to formation?

Yinhan_Liu_1D

We've learned that enthalpy with subscript f is the standard enthalpy of formation.

What does the "c" mean?

I saw it on HW:8.57.

Appreciate your help; )

Yinhan_Liu_1D

Hi, dear class, I looked up the solution manual. It is using the formula involving logarithm (which is on the formula sheet too). However, we have not talked about this in class before. Should we know how it is derived? Or we just need to know and use the formula when it comes to reversible expansion.

Yinhan_Liu_1D

Dear fellows,

Did you get the workbook when you are buying the course reader?

I didn't get the workbook as I had when I was buying CHEM 14A course reader.

I would really appreciate your reply!

Best,

Yinhan_Liu_1D

Professor Lavelle,

You mentioned in the Email that we will finish the syllabus on Wednesday and all material covered will be tested on.

Does it mean that we will finish buffers and titrations?

Yinhan_Liu_1D

I mean the nH20 that is attached after the complex (not within the coordination sphere).

Yinhan_Liu_1D

"Aqua" denotes a coordinate covalent bond between water and the central atom in the coordination sphere, while a hydrate is a water molecule outside of the coordination sphere that is attracted to a ion or polar compound via hydrogen bonds. So, you mean that the water molecule is bonded t...

Yinhan_Liu_1D

Hi, I understand that aqua is the OH2 which is within the coordination sphere (square brackets) while hydrate is not (it is written last after a dot). Does any one have an in-depth understanding of the structural or chemical difference between the two structure? Since they are both neutral and they ...

Yinhan_Liu_1D

Hi, If you're looking at the anionic ligand chart, then I believe SO42- and OSO32- are the same molecule. They both indicate a sulfate molecule which is known as sulfato when it acts as a ligand. The reason why the chart writes OSO32- is to emphasize that it is the oxygen that forms a bond with the...

Yinhan_Liu_1D

Hi, all, As I was go over the naming chart in our course reader, I found that it names OSO32- as sulfato. However, as I was searching on line, all the sulfato structure I have found is centered at "S". 1) Can anyone kindly show me how center at "O" would look like? 2) Do the SO42...

Yinhan_Liu_1D

I am wondering, for example, if the solute is ZnCl2, and in the chemical reaction, its phase is (aq), when we plug in the activity of this part, should we plug in [ZnCl2]^n or [Zn]^n [Cl]^2n?

In the solution, ZnCl2 appears as ions, right?

I would really appreciate your help!

Yinhan_Liu_1D

In homework 17.31 1) Why is the "aqua" in c) written as H20 not OH2? Does it matter 2) Why is it Na[Fe(OH2)2(C2O4)2] but not [Fe(C2O4)2(OH2)2]? I remember in the book, it says that the sequence of naming is different from the sequence of writing them down. (i.e. when writing them down, &qu...

Yinhan_Liu_1D

I tried to figure out what the Lewis structure of this complex would look like, but I can't figure it out, especially the electron distribution and how they altogether make it to 2+.

Is it that because all the OH2 are neutral, but Cu has 2+ ?

I would really appreciate your help.

Yinhan_Liu_1D

In the textbook p140, it mentions that "the four valence orbitals provided by the sulfur atom and the six orbitals of the fluorine atoms that point toward the sulfur atom, a total of 10 atomic orbitals..." 1) Why does sulfur atom has FOUR valence orbitals? Why not 6? 2) Why is the bond ord...

Yinhan_Liu_1D

By calculation it is 2.5.

But what does this mean?

Does it mean that there's only 2 bonds? or...

I would appreciate your help.

Yinhan_Liu_1D

Is it due to the decreased energy level when S character increases?

I would appreciate your help.

Yinhan_Liu_1D

In the solution manual, it mentioned the Cl-Te-Cl bond angle could be approximately 90 degrees and 120 degrees. Since there is a bent on the original see-saw shape due to the lone pair, does the 120 refer to the original 180 degree between the axial Cl-Te bond? Does the 90 degree replace the origina...

Yinhan_Liu_1D

Is it similar to H2O? Since they are bothAX2E2.

Is the Electron arrangement for ClO2- trigonal pyramidal and the Shape angular?

I would really appreciate your help!

The bond angle is also less than 109.5, right?

Yinhan_Liu_1D

According to the text, the greater the difference in electronegativity, the greater the ionic character of the covalent bond.

Li has Higher Electronegativity than K.
Why does LiF have higher percentage of ionic character than KF (in the percentage graph on page 92)?

I would appreciate your help;)

Yinhan_Liu_1D

On textbook p88 self test 3.10B

I would appreciate your help

Yinhan_Liu_1D

When forming cations, the outermost electrons are removed. In Au the outermost electron is found in the 6s state since typically the 6s state is considered to be higher in energy and therefore farther away from the nucleus than the 5d state. This means that it is easier to remove electrons from the...

Yinhan_Liu_1D

Gabrielle Giang 1B wrote:I'm pretty sure that b) is representing the ground state for N. The electron configuration for N is 1s^2 2s^2 2p^3, and that is what's shown. There are 3 unpaired electrons in the 2p orbital.

Thank you. Yes, I think so.
It's just the solution manual which says that it's not the ground state.

Yinhan_Liu_1D

When removing one electron from Au, why is it not in 5d orbitals but the only one in 6s orbitals?
Pt, the one that is directly before Au has 5d^9, right?

I would appreciate your reply.

Yinhan_Liu_1D

Why is the b) choice NOT representing the ground state of N?

I would appreciate your help.
;)

Yinhan_Liu_1D

LOL... I think I get it.
The ionization here happens mostly within the first two groups.

In the first group, when the first ion is removed, we have to remove one ion from the core noble gas, which would be very hard, because it's already a stable formation.

Yinhan_Liu_1D

It's in the thinking point on P54.

I would appreciate your help.

Yinhan_Liu_1D

They describe the locations of electrons in a P-orbital. So instead of saying "these electron are in the front and back," we can say "their positions are on the x-axis" since they are in P-orbital, we state their location as "Px" same idea for Py and Pz Do you know how...

Yinhan_Liu_1D

In the book p37, it asks "How would you expect a 1st-orbital in He+ to differ from the sam orbital in H?"

They have the same wavefunction, right?

I can't figure it out. It would be great if you could help me.

Thanks a lot;)

Yinhan_Liu_1D

Is it because that the zero-point energy is already E1?

Yinhan_Liu_1D

Are the electrons that are very close to nucleus some what "confined" to those level? When delta X is small, delta p is very big. Does it mean that those electrons are extremely "random" in their velocity (they change velocity constantly)? So that they have really high energy lev...

Yinhan_Liu_1D

Hey, class.

I am wondering up to which topic will the first quiz cover.

I would really appreciate your reply.

Yinhan_Liu_1D

Hi all.
I understand how to get the answer.
But I just have a conceptual question: what does the "wavelength of the baseball" mean in reality? Is it the trajectory? Or is it the vibration?

I hope you can help me understand that.

Thank you!

Yinhan_Liu_1D

Will the peer facilitators be holding any review sessions? (i.e. will the session be only in the form of Q&A?)

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