The Periodic Table - 2016-09-26

« first day (1614 days earlier) ← previous day next day → last day (2769 days later) »

3:59 AM

5

Q: Reductions with BH3 in THF

I've always known $\ce{BH3}$ as a reagent for alkene hydroboration. Recently in class we talked about its use as a reducing agent for carboxylic acids too (it reduces them to alcohols). Now obviously $\ce{BH3}$ is an electrophile and I don't think it reacts by donating hydrides like $\ce{NaBH4}$ do

organic-chemistry reaction-mechanism redox carbonyl-compounds

1 hour later…

5:06 AM

@BountyHunter Hmm, this question has a really straightforward answer..

I'm not rep-greedy enough to bother with it.. for now

5:21 AM

OP last seen on Jan 2. :(

4 hours later…

9:41 AM

is any hydrocarbon soluble in water?

maybe this? !!img/cyclopentadiene

user image

oops it's insoluble

10:42 AM

!!img/циклопентадиен

No result found.

!!img/cyclopentadiène

No result found.

Heh, English only.

gosh, why delete your comment...?

sigh

10:45 AM

@orthocresol what? :O

O, hi @orthocresol, btw!

@Wildcat haha sorry... just frustrated with this internal energy vs enthalpy question on the front page, the guy deleted his comments

@orthocresol hmmm, thermodynamics...

In the mean time I'm frustrated with this question and answer:

4

Q: A comprehensive list of theoretical approximations that are used in computational chemistry

I am having trouble recognizing all the approximations that are used in computational chemistry. I would like to start an answer list (similar as to the list of resources for learning chemistry) that addresses this question. I will try to answer this question myself. I am hoping that anyone who...

computational-chemistry theoretical-chemistry

11:05 AM

@Wildcat What about it? (It's very ambitious I must say...)

Yes, and too broad.

Martin - マーチン

well....

the resources question was ambitious... and see how well that worked out

well...

taking into account that the current answer is of a very low quality...

I wouldn't be so optimistic in that case.

Clearly, too broad anyway.

Martin - マーチン

@Wildcat it was upvoted quite a lot though.

@Martin-マーチン typical (online) democracy.

Martin - マーチン

11:15 AM

i also have to admit, there are still a lot of missing things in chemistry.stackexchange.com/q/37303/4945 and we planned that thing for quite a while...

There are some areas of human activity (science, for example) where democracy makes more harm than good.

Martin - マーチン

now we are kinda banking on what has been done

@Martin-マーチン certainly

I felt very strongly that it was too broad, but if it is a community effort it can be done well, (point in case being of course the resources thread) so I figured I'd give it a chance.

Martin - マーチン

yeah I agree with that, but it's a big project, and without people backing it up it's not going to work out

11:17 AM

I think we still are lacking a critical mass of professional chemists out there.

Martin - マーチン

i also spent quite some time on re-layouting the whole thing, because it was a mess to read in the first place

@Martin-マーチン yep, we need more humans!

Martin - マーチン

@Wildcat it's usually that the real professionals are working...

@Martin-マーチン Right, but still we have few out there that are quite active. And there should be more somewhere.

We have to find them! :D

Physics.SE is much more rich in professionals in different areas of physics.

Martin - マーチン

@Wildcat gotta catch 'em all!

11:21 AM

@Martin-マーチン :D

Is there any chance the site could be promoted in some journal?

Say, J. Am. Chem. Soc.

Martin - マーチン

because physicists have no live ...

@Martin-マーチン lol, but don't tell them about it!

Martin - マーチン

well... i mean why not

@Martin-マーチン or no jobs in the industry

Martin - マーチン

@Wildcat they wouldn't understand

... anyway

11:23 AM

@Martin-マーチン a wild @Loong appeared

Martin - マーチン

hahaha!

:O

Martin - マーチン

that reminds me... I have not been playing in a long time because of the bs weather we have right now

I stopped after I had got all 145 Pokémon that I could get.

Martin - マーチン

@Loong holy cow I'm not even close to that O.o

11:27 AM

@Loong I have 54...

I don't know how to reply to your "question". Please help! — Curt F. 8 hours ago

:D

Martin - マーチン

@Loong OMG

i kind of desperately want to delete that...

@Loong flagged as parody

11:41 AM

hi everyone

would any hydrocarbon be soluble in water?

11:52 AM

@user34388 Benzene is probably one of the hydrocarbons that are a bit soluble in (warm) water. Maybe 1 g/l or more, depending on temperature.

@Loong what about cyclopentadiene?

Well, now we have a hybrid question...

1

Q: Resources to learn computational chemistry?

I am interested in learning computational chemistry to explore the possibility of postgraduate work in quantum/theoretical chemistry and would like to attempt self-studying. I know the basics of quantum mechanics on par with a p.chem course and have an understanding of linear algebra and differe...

physical-chemistry quantum-chemistry computational-chemistry theoretical-chemistry

A duplicate?

Hybrid of the compchem thread and the resources thread :D

Yeah, probably a dupe.

Martin - マーチン

almost certainly...

11:56 AM

@orthocresol much closer to the second one, I think.

@Wildcat Yes, certainly

Martin - マーチン

I mean that was the whole reason to create the resources q&a so that we have a handle on that

Hmm, what can be improved on the current resources thread?

Martin - マーチン

@orthocresol fill the void ;)

@Martin-マーチン besides, here comes the battle "computational vs. quantum chemistry" one more time! Boy, I already hate this question!

Didn't we have a meta thread on that issue?

Martin - マーチン

11:58 AM

@Wildcat don't forget about theoretical chemistry

We have. meta.chemistry.stackexchange.com/questions/3161/… And... It was me who started it. :O

My memory playing tricks again.

OK, now the fun starts. I'm beginning the downgrade to Win 7 on my PC! :|

Martin - マーチン

@Wildcat I don't have enough lols for that

@Martin-マーチン just couldn't tollerate Win 10... I tried, but... :(

Martin - マーチン

@Wildcat but, but, but.... I read they are bringing BASH to windows

that would be the only reason for me to upgrade

@Martin-マーチン I don't think it's quite that appealing. From what I heard, they're just introducing the ability to run *nix-native binaries on Windows... probably in a special runtime environment or something.

I would be shocked if they implemented a full *sh shell of any type.

Martin - マーチン

12:07 PM

@hBy2Py they do from what I read, a complete implementation of a ubuntu sub system

@Wildcat I cancelled every Win10 upgrade I saw with extreme prejudice. Figured if MS wanted me to upgrade so badly, I probably very badly didn't.

@Martin-マーチン Huh! Well, if so, good on 'em!

Martin - マーチン

not to sure though... just read it on the bus while on mobile... could misremember that

however, when you are somewhat forced to run windows because of office constrains, it's great to have something to run some native linux programs in it

from what i gathered graphical stuff it still quite wonky

yep

Martin - マーチン

but i don't want to risk more pc trouble than i already have just to try it

:D

user228700

12:13 PM

Hello everyone :-) I have a very quick question; do u think that it will be easier for me to grasp the concepts of "Ionic Equilibrium" after having learnt chaps. of inorganic chemistry such as "Chemical Bonding"..?

user228700

Or won't it affect anything..? (Even though I do have some basic knowledge regarding chemical bonding and all, please go ahead and assume that I am learning these topics for the first time for the purpose of this query)

user228700

Anyone..? Please?

user228700

@MAFIA36790: Any thoughts?

user116211

What?

user228700

@MAFIA36790 Um, did u read my whole message?

12:24 PM

I don't even remember what ionic equilibrium is. =>.<=

user228700

@Wildcat Oh, I see :P

user116211

The room is starred; so even if I enter any one of the rooms (presently maths), they show me logged in every room I starred. But I'm practically not here....

user228700

@MAFIA36790 Uh, OK...

user116211

@KaumudiHarikumar In order to understand equilibrium, you need to know thermodynamics, that's it.

@KaumudiHarikumar I quickly google what ionic eq. is, and I would say you don't need to know a lot about chemical bonding to understand it.

user228700

12:26 PM

@MAFIA36790 I mean Ionic equilibrium. There isn't that much thermodynamics involved...

user116211

@KaumudiHarikumar I've noticed that. Whatever it is, you need to know thermodynamics.

@KaumudiHarikumar ionic eq. is just a particular kind of td eq.

eq. is all about td

but it is a relatively simple concept

user228700

Crap. Okay. Thanks, guys :-)

@KaumudiHarikumar That is not a crap. That is chemistry! :D

But what problems do you have in understanding ionic eq.?

@KaumudiHarikumar It's probably good if you know how some simple molecules and ions (e.g. H2O, H3O+ and OH-) look like before you use them in equilibrium reactions.

user228700

12:39 PM

@Loong OK. That much I definitely know :-)

user228700

@Wildcat Hm :P

user228700

Also, as a rule of thumb, organic molecules don't dissolvevin polar solvents such as water, yes?

@KaumudiHarikumar OK. Then see how many ionic equilibrium problems you can solve based on your knowledge. You might want to return to reading some basic inorganic chemistry before you expand the topic of ionic equilibrium reactions to redox reactions.

user228700

@Loong OK, thank you :-)

@KaumudiHarikumar "organic molecules" can be anything. Pentane is an organic molecule that doesn't dissolve in water; however, ethanol and acetic acid are organic molecules that readily mix with water.

@KaumudiHarikumar If you need a rule of thumb, organic molecules with a large hydrocarbon part (e.g. a long alkane chain) don't mix with water.

1:03 PM

What is 0.1 N solution of HCl?

> 0.1 Н раствор HCl (in Russian)

I wonder if "0.1 N solution of HCl" is a correct translation

Equivalent concentration

In chemistry, the equivalent concentration or normality of a solution is defined as the molar concentration ci divided by an equivalence factor feq: Normality = ci/feq == Unit symbol NEdit == The unit symbol "N" is used to denote "eq/L" (equivalent per liter) which is normality. Although losing favor, medical reporting of serum concentrations in "meq/L" (= 0.001 N) still occurs. == UsageEdit == There are three common areas where normality is used as a measure of reactive species in solution: In acid-base chemistry, normality is used to express the concentration of hydronium ions (H3O+) ...

@Loong I found this too.. trying to wrap my head around this

> One liter of a 0.1 N solution of HCl, contains 0.1 mole of HCl.

Is this correct?

It is simply mole/liter?

Not really

In this case, yes, but not really

That wikipedia article says it all.

> In chemistry, the equivalent concentration or normality of a solution is defined as the molar concentration ci divided by an equivalence factor feq.

Clear as day!

@CowperKettle It is a correct translation, and you can still find it in the literature; however, the use of "normality" is no longer recommended.

1:09 PM

So it is 0.1 mole of HCL for hydrochloric acid, but 0.05 mole for a diprotic acid?

The way Wikipedia says it is just Chinese to me.

@CowperKettle yes

user228700

@Loong OK, thank you :-)

Thank you, that's a bit clearer, @Loong!

I'll try reading up on this.

Actually, you should write something like "a hydrochloric acid solution with a concentration of c (HCl) = 0.1 mol/l". However, chemists are lazy writers, and so you often just see the abbreviation "0.1 M HCl", which is not a proper use of quantities and units.

@Loong My table will explode. (0: This is from a pharmacological document, the contents of a vial.

It's inside a table.

It says "input vial contents:"

"0.1 N solution of HCl"

1:18 PM

Since you are just translating a text and not writing your own work, keeping the "0.1 N solution of HCl" from the original is probably correct.

Yay! (0:

BBL!

Tables are hard to translate because they use odd language

Compressed and not confluent with the usual idiomatic forms of the language

"Ouptut vial: Used solution of NaOH (discard)" - for instance, I'm not sure how to indicate that this solution is for "utilization" (should be gotten rid of).

Maybe it's "discard", maybe it's (for utilization) or something else in English.

We washed the electrophoretic capillary under pressure with NaOH and should now discard the NaOH.

hmm.. "for disposal"?

still a bit ambiguous

might be interpreted as "для складирования" rather than "для утилизации"

but "for utilization" is just plain wrong, I think

it means "для использования"

Are you Russian too, @Wildcat?

@CowperKettle yep ;)

utilization is an ambiguous word in English

@Wildcat Great! (0:

1:30 PM

@CowperKettle true, disposal is way better in that contex

BBL, I'll go for a jog until (while!) there is still some light in the sky

@Wildcat Thanks!

just a little bit ambiguous still

4 hours later…

5:41 PM

So one mole of H3PO4 has 6.022 x 10^23 molecules. 2 moles of it has = 1.20 x 10^24. Then you divide that number by the number of atoms, witch in H3PO4 = 8. So you get 1.505 x 10^23 atoms in H3PO4? — Josh Castillo 9 mins ago

sobs

5:54 PM

At least, he no longer includes the molar mass in the calculations.

Poor guy

He's confused.

6:31 PM

> An enzyme present in the ISOQUANT kit (protein isoaspartyl methyltransferase) catalyzes the reaction between isoaspartic acid residues formed from asparagine residues via deamidation (and, to a much lesser degree, from aspartic acid residues) and S-adenosyl-L-methionine.

What's the key difference between asparagine and aspartic acid?

Ah. Asparagine has two HN2 groups, while aspartic acid has one HN3 group

> Isoaspartyl formation reaction of Asn-Gly (top right) to Asp-Gly (at left) or iso(Asp)-Gly (in green at bottom right). here

Does "Gly" mean that the amino acid is connected to glycine?

6:47 PM

user image

Are there two Glycines flanking Aspartic acid in the picture?

1 hour later…

7:55 PM

user image

Windows 7 after-SP1 updates... More that 200 fixes, but the RAM usage is just crazy.

Typical MS stuff, I would say. XD

pentavalentcarbon

Why would a computational chemist use Windows :(

@Wildcat It's during updates - that's why usage was still big

@pentavalentcarbon For gaming :D

@pentavalentcarbon cause Linux still sucks on laptops. :| I spent few days trying to turn the keyboard backlight, tune the fan speed, etc. few weeks ago, but no luck. Battery life still sucks on hybrid graphics as well, unless you turn the discrete card completely off, which is nonsense.

@Mithoron I'm not into games. In the last few years I played only single game and it is available on Linux. :)

8:13 PM

@Wildcat There's more and more games available, on Ubuntu at least

@Mithoron yeah, but these are just few patches. There is obviously some memory leak or completely stupid algorithm in Windows Updates. Installing any single patch requires just a little bit of memory, but installing them sequentially requires few GBs! Something is wrong out there.

@Mithoron which is nice.

pentavalentcarbon

@Wildcat This is unfortunately still very true. If my laptop wasn't a Mac, I'm not sure what I'd do for mobile.

U have a lot of ram so Y not use it ;)

pentavalentcarbon

@Mithoron Oh, of course, but for day to day, you know, actual work...

@pentavalentcarbon ;)

8:17 PM

@pentavalentcarbon best combo for actual work for me is Mac + Windows VM. :)

Linux is great on supercomputers.

0

Q: 2016 Moderator Election Q&A - Question Collection

Chemistry is scheduled for an election starting next week, October 3rd. In connection with that election, we will be hosting a Q&A here for candidates. This will be an opportunity for members of the community to pose questions to the candidates on the topic of moderation. Participation is comple...

discussion featured election

5

8:39 PM

@Wildcat did you see that feed o.O

@Mithoron do you mean previously? No. But it was just created. Or do you mean there is some interesting content there?

@Wildcat I just mean it's surprising (at least for me)

@Wildcat And what content? There's gonna be mod election here in a week!

@Mithoron, so elections just came as a surprise for you? :D

Well, I heard about Physics but...

This year I voted on elections for the first time in my life. I mean, on real elections to our parliament.

Completely meaningless, of course. :D

"If voting made a difference, they wouldn't let us do it."

A quote often (incorrectly) attributed to Mark Twain.

8:53 PM

Well, sometimes it makes a difference

But at least now I have counterargument for political disputes: I was there and voted. And it didn't change anything. XD

Cause some people like to argue "But you didn't even try!" when you say that elections are just a joke.

@Mithoron they do so too rarely

I mean elections make a difference too rarely.

@Wildcat I feel last elections here made quite a difference in quite bad way :(

@Mithoron hmmm... what happened?

@Wildcat Change in parliament from mediocre to bad :( (also government etc)

@Mithoron Wait, did you mean "in Poland" by "here"?

9:02 PM

Indeed

Huh, at first I thought you are talking about the site. XD

@Wildcat :D

Well, I honestly don't know how bad your parliament is, but I bet our is even worse. :|

@Wildcat Yeah it looks like, but talking about site elections is more optimistic, so lets do that one ;)

It may bring bigger change then last one

2 hours later…

11:02 PM

Is it that when i construct LCAO, i can make the p orbitals point in any direction as long as they are orthogonal? Can i make p orbitals of different atoms point at different direction as well?

« first day (1614 days earlier) ← previous day next day → last day (2769 days later) »

Transcript for

Sep '1626

The Periodic Table

Haikus are awesome / Chemistry's even better / So pull up a chair

blowing-the-lab-up german-stuff hullo love-you-all martin table-flipping tre welcome

join this room
about this room

00:00

06:00

12:00

18:00

all times are UTC

site design / logo © 2024 Stack Exchange Inc; legal

mobile