The Periodic Table

user228700

12:13 AM

Hi, everyone :-)

user228700

I've a quick question. I came across the following question on CSE:

user228700

chemistry.stackexchange.com/questions/32450/…

user228700

When I saw the four options, I didn't think of actually adding a hydrogen to each compound or anything. Rather, I used this definition:

user228700

> "Heat of hydrogenation of alkenes is a measure of the stability of carbon-carbon double bonds. All else being the same, the smaller the numerical value of heat of hydrogenation of an alkene, the more stable the double bond therein."

user228700

So I tried to figure which of the given alkenes would be most stable.

Zhe

12:15 AM

Stable relative to what?

user228700

It is clear that trans-2-butene is the most stable of all of them because in the first place, it has 6 $\alpha$ hydrogen atoms, so it has 6 hyperconjugative structures. Secondly, it's trans → less dipole moment, compared to the cis alternative.

user228700

Is this reasoning OK for a question like that?

user228700

@Zhe I...dunno .__.

Zhe

You have to be careful here

When you talk about stability, are your comparing them to each other?

Or to the corresponding alkane?

Also, why is dipole moment important?

@Kaumudi

user228700

@Zhe To each other, I think.

Zhe

12:27 AM

Then that doesn't work unless all of the alkane are the same energy

user228700

:-/ We haven't been taught exactly what it is we're comparing to. (Does it help to know that I've only just graduated high school?)

user228700

Dipole moment, hmm. We had been taught that the trans isomer is more stable than the cis isomer because the dipole meant in trans is basically 0 but not in trans.

user228700

...and I just learned that dipole moment doesn't really have anything to do with stability.

user228700

Awesome.

user228700

OK, I did find s'thing that matches what my teacher once taught me:

user228700

12:42 AM

> "Dipole moment tells about the nature of the bond. Higher is the dipole moment, higher will be the ionic character of that bond and lower will be the covalent character of that bond.
If the ionic character is higher, then the reactivity will also be higher and ultimatly stability will be lower.
e.g hydrocarbons have no reactivity due to zero dipole moment while carbonyls are highly reactive (have dipole moment). Many aldehydes are very unstable."

user228700

1:11 AM

I...have a quick question again.

user228700

user228700

^ Why is that correct? (Given in my textbook)

user228700

1:33 AM

Does anybody know the relation b/w solvation and inductive & mesomeric effects?

Melanie Shebel

1:59 AM

So I'm anosmic but there are a few things I CAN smell on occasion. Since smells are highly based on biological receptor things (not a biologist) and the odorous chemicals that are picked up by these receptors, I was wondering if there would be a way to determine links between the chemical structures of what I CAN smell. (I wanted to phrase this question on chem.se, but didn't how.)

orthocresol

3:09 AM

@MelanieShebel It should be possible to list everything you can smell, but whether you could find a link between them would not be guaranteed. Furthermore to identify its binding to a specific receptor, you would first have to identify the receptor, characterise its structure (usually X-ray crystallography afaik), then either carry out some experiments to determine whether there is binding (there are many) or do some in silico molecular docking.

Proteins are really tough creatures to work with ;)

We like to talk down to biologists (xkcd), but you have to respect the work they do - biological experiments are a hundred times harder than chemical ones.

CowperKettle

3:38 AM

@paracresol Cossack song of the day

Ой розвивайся та сухий дубе - Ukrainian folk song // by "Chervona kalyna"

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I tried to translate it, because it is beautiful, but it's very hard

CowperKettle

3:50 AM

Як за дальнім небосхилом (Ukrainian folk song)

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Another one, much like the first

Гей ви, Стрільці Січовії _ Ukrainian song

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A funny march song. It starts all nice and patriotic about a captain and his soldiers. Soon the listener learns that the captain squandered the soldiers' money on booze and gipsey women.

"Sich Riflemen Song"

I translated it quite quickly

Melanie Shebel

5:17 AM

I can only smell roses, freshly made toast, and things cooked in butter. It's weird.

ffahim

6:00 AM

Hlw

I would like to know that do both AgOH and Ag2O precipitate ?

ffahim

8:11 AM

Anyone there

user116211

10:16 AM

Thanks @ortho; the comments are insightful; will check the link later.

orthocresol

@MAFIA36790 No problem, sorry for the delayed response.

user116211

No worries; sorry from me for bothering you; but the comments seem to be beneficial to the post. Thanks.

orthocresol

Well, it's not a bother!

And thus @MAFIA36790 vanished into thin air...

0

Q: How to draw hyperconjugating structures?please do help

how to draw hyperconjugating structures? Please explain

organic-chemistry

If MAR was here, he'd have a field day with this question

koolman

10:43 AM

I am comfused in below problem

Somebody can help me in that

In the above clainsen condensation reaction
Why the reagent marked does not attack the carbonyl carbon of other compound (given reactant)

DHMO

12:47 PM

Biting Sodium Metal?!?!

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CowperKettle

12:57 PM

> Whoever bites sodium, he is quick to learn chemistry the worst way possible; whoever learns chemistry the worst way possible, enters Heaven pretty quick. Thus, let us drink beer.

2

hmm

> The pH was kept at the needed level during culturing by feeding CO2 through the sparger when the medium turned alkaline and a 7.5% solution of NaHCO3 if the medium turned acidic.

organic chemistry

Chemobot

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