The Periodic Table

DHMO

11:19

@gavin where does the radical come from?

Gavin Machell

No idea. These are half cell potentials from the list of standard electrode potentials and this involves peroxide, so I guess you'd start with that.

DHMO

11:46

alright

Rubisco

Hullo @Gavin! Welcome to chat!

Gavin Machell

@Rubisco Hi there

Rubisco

How're ya doing?

Gavin Machell

Am fine thanks for asking - how're you?

Rubisco

Great

I'm having Trumps.

Gavin Machell

11:56

I wish there was a supository for that.

Rubisco

i.e. cheetos

Gavin Machell

Oh, I thought you were being political

Rubisco

Well, it's kinda a political joke

Gavin Machell

Gotcha.

Rubisco

Downvoted thingy of the day

-18

Q: Should people answering questions be allowed to vote on other answers [to same question]?

Personal experience: I answer a question that had too little attention with a problem I found compelling, so I spend some time reproducing the problem and propose what I think is an applicable solution. More than 48 hours later with absolutely no activity during that time except a second potentia...

feature-request

I see three very different answers, none of them being really ALL the differences between the two compounds. If half of the questions on this site were like yours, all the experts you seek answers from would've packed on and moved. In other words, you're misusing the site, not using it. — Rubisco 6 secs ago

This guy is really, I MEAN REALLY, getting on my nerves

Jan

12:12

@Rubisco I thought I said yesterday I would post something yesterday? I didn't hear any immediate complaint …

Rubisco

@Jan . . .

YOU MISUSED MY ATTENTION SPAN

Jan

I beg your pardon =C

Rubisco

I don't remember you saying you'd post something right away

So either I was careless, or I was careless

Jan

16 hours ago, by Jan

@Rubisco I was thinking of doing that. I’ll do it later today =3

Rubisco

Shit.

DHMO

12:17

@enzyme what's your new name?

Rubisco

Not yet decided

DHMO

i'll call you cyanide then

Jan

Btw, I deleted the question.

DHMO

@Jan whyyyyyyyyyy

Rubisco

2 mins ago, by DHMO

@Jan whyyyyyyyyyy

As Lord Mart says, this site is slooooow

Jan

12:21

@Rubisco Please decide whether it was too soon or not ô.o

Rubisco

It wasn't

Undelete it

Jan

*facepalm*

Rubisco

Unnerving is not that profitable a business but it's fun.

Jan

There you go, undeleted.

Should I now go and delete it again?

Rubisco

Add an answer of your own

CowperKettle

12:34

Afternoon!

> Sheath Gas Flow Rate: 40 arb
Aux/Sweep Gas Flow Rate: 20 arb

What could this "arb" mean?

DHMO

@CowperKettle context

arbitrary unit

CowperKettle

@DHMO MS ionization source

DHMO

Source:

Arbitrary unit

In science and technology, an arbitrary unit (abbreviated arb. unit, see below) or procedure defined unit (p.d.u.) is a relative unit of measurement to show the ratio of amount of substance, intensity, or other quantities, to a predetermined reference measurement. The reference measurement is typically defined by the local laboratories or dependent on individual measurement apparatus. It is therefore impossible to compare "1 arb. unit" by one measurer and "1000 arb. unit" by another measurer without detailed prior knowledge on how the respective "arbitrary units" were defined; thus, the unit is...

CowperKettle

@DHMO so I guessed!

@DHMO thank you!

DHMO

How many double bonds maximum for chromium?

CowperKettle

12:36

Dunno

DHMO

is CrO3 hypervalent?

20 valence electrons

CowperKettle

@Rubisco To me, everything above 24C is "frying" (0;

Jan

@DHMO Cr^6+ and 3 O^2- ;)

DHMO

@Jan why are they depicted as having double bonds?

pentavalentcarbon

@orthocresol That's all it is, IIRC. There is a J Chem Ed somewhere out there about how the inversion is actually mediated by tunneling through a barrier.

DHMO

12:41

@Jan I guess this is more accurate:

this actually obeys the 18-electron rule

Jan

@DHMO Yes! =)

@DHMO Because Linus Pauling hated formal charges.

DHMO

@Jan do you happen to know why it is not planar?

it is C3v instead of D3h

on the other hand, sulfur trioxide is planar.

Jan

Nope, I don't. I would've assumed D3h, I think.

DHMO

@Jan on the other hand, its dimer is bonded like diborane...

(D2h)

the O=Cr=O angle is 113.3 deg

slightly less than 120 deg (planar SO3)

@Jan another clue: CrO3^- is planar

Jan

12:57

CrO3- has a different oxidation state than CrO3 and thus is irrelevant ;)

DHMO

:o

CowperKettle

13:27

I don't understand what "tube lens" is - and why it is "lens"

I was told by the Russian author that the Russian phrase "transporting capillary" is translated as "tube lens"

O_O

So "transporting capillary voltage: 85 V" is "tube lens voltage: 85 V"

I thought that "lens" meant "concave or convex item for focusing or defocusing rays"

orthocresol

@Jan I don't know. I thought it was too soon and that it might affect the election itself.

CowperKettle

0

Q: What is a "tube lens" in a mass-spectrometer ion source and what does it do?

I came across the Russian phrase "Transporting capillary voltage: 85 V" in a text I was translating. The paragraph was describing the operating parameters of an electrospray ionization-based ion source in an MS system. The author told me that the proper English translation is "Tube lens voltage...

terminology mass-spectrometry

orthocresol

13:43

But, I don't really want to be a spoilsport. And if it affects the election process, then so be it. I'm not going to throw a tantrum and leave the site if I'm not elected, or if someone I didn't vote for is elected.

Which is why I deleted my comment earlier (before I saw your reply actually) :)

Loong

I'd add that using dimensional analysis is a good way to keep things straight until you're comfortably just grinding the numbers. — MaxW Sep 9 at 23:52

sigh

Jan

@Loong So many things that could be interpreted into that sigh there …

Loong

That's one of the reasons why I put this in the example questions:

area51.stackexchange.com/proposals/102351/science-educators/…

btw:

245

Q: Allow downvoting comments

Answers and questions allow both upvoting and downvoting - comments, however, only allow upvoting. I think it would be useful to allow downvoting of comments for two reasons: First, if you accidentally upvoted a comment you didn't intend to Second, if you strongly believe that a comment is dis...

feature-request status-declined comments down-votes comment-voting

Jan

@Loong status-declined

Loong

yeah

7 mins ago, by Loong

sigh

DHMO

14:05

like

how come the dissolution of table salt is endothermic?????????????????????????????????????????????????????????????????????‌???????????????????

Jan

@DHMO The number of question marks is inversely proportional to the question's perceived seriosity.

3

With that, I'm off o/

DHMO

Why is the dissolution of table salt in water endothermic?

orthocresol

@Jan why??????????

:(

Cya

DHMO

@orthocresol why?

Why can beryllium (Be) form covalent bonds?

Aaron Abraham

14:54

@pH13-YetanotherPhilipp Well here's the question anyway:

0

Q: Why does the BET equation take into consideration a multimolecular-layer, even though it deals with Chemisorption?

I came across the Brunauer-Emmet-Teller (BET) equation recently, and one thing that I found strange was an implicit reference to the formation of molecular multi-layer. In the BET equation (according to Wikipedia ) $\mathrm{Q_{L}}$ refers to the heat of adsorption of the second and higher lay...

surface-chemistry adsorption

@DHMO You're still here?

DHMO

@AaronAbraham yes

Aaron Abraham

(talk about stamina...)

DHMO

stamina is the ability of an organism to exert itself and remain active for a long period of time, as well as its ability to resist, withstand, recover from, and have immunity to trauma, wounds, or fatigue

Aaron Abraham

extend that argument to molecules too...

DHMO

??

I have to go now

CowperKettle

16:57

Can you bind your analyte in the column by pipetting?
in the microcolumn
I got a description of a microcolumn pre-MALDI procedure where a 0.1% TFA-acidified sample is "bound by repeated pipetting (10 repeats)"

Loong

@CowperKettle The pipetting doesn't bind anything itself; it just transfers the solution. That microcolumn is probably used for some kind of solid phase extraction. So if you pass your solution through that column, the column gets loaded with the sample.

pH13 - Yet another Philipp

@Rubisco last 2 hours to throw in the towel

CowperKettle

17:13

> We washed a microcolumn with 80% acetonitrile, then with 0.1% TFA in water. We next bound the samples acidified with 0.1% TFA by multiple pipetting (10 repeats). Then we washed the column again with 0.1% TFA, then eluted the samples onto the MALDI plate using 20 mg/ml matrix (2,5-dihydroxybenzoic acid) in 50% acetonitrile in 2 mM sodium acetate.

@Loong what is "solid phase extraction"?

It is used to prepare the sample before MALDI

They write: "we used the ZipTip C18 microcolumn for the application of the sample"

And then goes this long sentence

Loong

@CowperKettle Do you know how liquid–liquid extraction works?

CowperKettle

@Loong vaguely

I don't understand this procedure at all.

Loong

@CowperKettle In principle, if you shake an aqueous phase with an organic solvent, the polar compounds stay in the water, the nonpolar compounds dissolve in the organic solvent.

9-BBN

If there is someone you knows how to use a ternary diagram I have question

CowperKettle

@Loong I see!

9-BBN

17:20

(Hello)

Loong

@CowperKettle Then you can separate the liquid phases and thus separate the compounds.

@9-BBN hi

@CowperKettle Now, imagine that only one of the phases is a liquid and the other phase is a solid resin.

CowperKettle

@Loong So you think they used the microcolumn to get rid of unnecessary components of the sample?

Loong

@CowperKettle Either that or they used the column to preconcentrate the sample.

9-BBN

OK so let me start, I have trouble reading those diagram the teacher have not explain "because it not really used" (big lol) hum, in a book (design of equilibrium stage processes) to find the composition choosing one point inside the triangle they make the perpandicular to the sides of the triangles from the points and they read the numbers on the side-scales. In my lesson the teacher do it drawing parallel of the sides and then reading. What's the difference ?

(In the book)

In my lesson

(How to stop a chat lol)

Loong

@9-BBN That diagram is correct for mixtures (alloys etc) of three components. The sum of the three values is always 100 %.

@9-BBN I am not sure what quantities are shown in this diagram and how the scales are supposed to work.

9-BBN

17:32

On my lesson it is molar fraction in %

CowperKettle

I found this: " PREISLER, Jan. Coupling of microcolumn separations to MALDI MS. Vienna: University of Vienna, 2007. Mass Spec Forum."

Loong

@9-BBN Your lesson is ok. I don't know what we can see in your book.

9-BBN

This is the percentage of concetration

of one

and the sum of all is 100

CowperKettle

Found something similar:

> Oligosaccharides released by PNGase F are separated from peptides and glycopeptides using a C18 Sep-Pak, and their methylated derivatives are characterized by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS).

ncbi.nlm.nih.gov/pubmed/19277556

So the microcolumn might be used to separate the stuff from peptides and glycopeptides (what are they? who knows)

Glycopeptide

Glycopeptides are peptides that contain carbohydrate moieties (glycans) covalently attached to the side chains of the amino acid residues that constitute the peptide. Over the past few decades it has been recognised that glycans on cell surface (attached to membrane proteins or lipids) and those bound to proteins (glycoproteins) play a critical role in biology. For example, these constructs have been shown to play important roles in fertilization, the immune system, brain development, the endocrine system and inflammation. The synthesis of glycopeptides provides biological probes for researchers...

CowperKettle

17:58

> The most common matrix for the analysis of glycans is 2,5-dihydroxybenzoic acid (DHB).

Now I understand what it was for in the procedure

The matrix absorbes laser energy and helps the analyte ionize

CowperKettle

18:13

> In our lab, we have chosen
to stabilize sialylated oligosaccharides using permethylation.

Now I understand what permethylation is for.

Nice

CowperKettle

18:30

Why would an empty column be washed with acetonitrile water 80:20?

Rubisco

18:44

5 hours ago, by Loong

7 mins ago, by Loong

sigh

@CowperKettle To clean it?

What do they wanna do with it?

orthocresol

19:15

This guy tried to assign an NMR spectrum before making sure that the total integration was equal to number of protons. :/

0

Q: Help assiging a 1HNMR of a Rh half sandwich complex

The complex I would like help assigning: This is the information from the 1H-NMR spectrum: I know that the relative intensity 15 is from the Cp* ligand (Pentamethylcyclopentadiene). I think H2 and H6 are equivalent and are the shift at 2.88ppm and that H1 and H5 are equivalent and are the...

inorganic-chemistry nmr organometallic-compounds

Rubisco

@orthocresol Can someone edit that 'help' out of the title, PLEASE

orthocresol

Go ahead.

It seems we have 56 questions with "help" in the title.

111 with "question".

Rubisco

@orthocresol If I go ahead, I'll fall off the sofa

orthocresol

26 with "doubt".

Rubisco

That's not much

Something to consider for TRE

orthocresol

19:18

Yeap.

Rubisco

I was thinking

SOCVR was a room intended for closing stuff

but in the end, they ended up doing everything

orthocresol

What does "everything" entail?

Rubisco

So I guess TRE will only remain TRE in the name, and turn into something bigger

@orthocresol Everything moderation-related

Loong

@Rubisco yeah, math.stackexchange.com has 74000 not-an-answers with "hint".

orthocresol

Just change what "R" stands for. It can be... refurbishment.

Rubisco

19:20

2 mins ago, by Rubisco

That's not much

orthocresol

Renovation. Repair. Rejuvenation. Restoration

Rubisco

We can just nuke the site and be done with it

Loong

36 mins ago, by Rubisco

5 hours ago, by Loong

7 mins ago, by Loong

sigh

Rubisco

@orthocresol What a poetically creative seal

The only thing @Ortho lacks right now is fluffiness

Diagram thingy of the day

More answers are welcome! :D It would help me to understand it more clearly. Thanks — Daksh Shah Feb 24 '14 at 18:18

This flaggable as too chatty?

Loong

@orthocresol and now the (η4-buta-1,3-diene)chlorido(pentamethyl-η5-cyclopentadienyl)rhodium(I) disappeared?

orthocresol

20:00

@Loong Seems so.

Loong

20:12

hi @ToddMinehardt

Now let's see how many users vote.

Todd Minehardt

hey @Loong!

i just cast my 3 votes

Loong

Last election, only 61 users voted.

@ToddMinehardt very good

Todd Minehardt

wow! that's all???

pH13 - Yet another Philipp

@ToddMinehardt I was also very surprised

Todd Minehardt

it's sort of like voter turnout here in the u.s. now that you mention it -

like 7% or something pathetic, i forget the stats

hi @pH13-YetanotherPhilipp -

Loong

20:14

This election, already 13 users voted.

user116211

The sixth one to vote \o/

user116211

@Penta is the first one to vote.

Todd Minehardt

where can you see how many people have voted? or is that a 10k thing? @Loong

Loong

@ToddMinehardt look at the badges: chemistry.stackexchange.com/help/badges/81?page=1

Todd Minehardt

@Loong - got it, thanks!

orthocresol

20:16

I don't dare to vote.

Loong

@ToddMinehardt subtract 60 (the old value before this election started)

Todd Minehardt

right, got that

user116211

This man asked Donald Trump a question and became a meme

pentavalentcarbon

20:32

:D :D :D

The whole election thing should be rewritten so you're forced to look at the questionnaire.

The nomination page is basically just a scientific abstract and we know how garbage those can be.

orthocresol

Which is why I tried to TLDR myself

I really don't want to make a choice.

:/

pentavalentcarbon

eh, just get it over with...I don't think anyone will get offended

DHMO

21:51

why is CrO3 C3v but CrO3^- D3h?

the O=Cr=O bond angle is 113°

the Cl-P-Cl angle in PCl3 is 109°

but the double bond causes extra repulsion

so indeed it might follow VSEPR..

i think the bond order is indeed 4 following the 18-electron rule

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