The Periodic Table

orthocresol

1:58 AM

@Loong I saw the physics nomination page yesterday... half of them didn't seem serious ._.

orthocresol

2:38 AM

I don't really follow other SE sites much, but there seems to be a really bad split somewhere.

user116211

@orthocresol Apart from ACM, Jim- the King, and the fluid-dynamics messiah tgp; all are joke candidates.

user116211

There is hell lot of drama going in the election; oh man....

user116211

Even they attacked me too!!

user116211

They think my single close vote closed their post.... damn ;(

user116211

11

Q: Can we try to cut the vitriol during this election?

Well, we're a day into the nomination phase of Physics Stack Exchange's third election. We already have 8 candidates for the two positions available, and no doubt we'll get plenty more. A pattern has begun to emerge, and it's not hard to see where it's leading. In both nominations and comments, ...

orthocresol

2:42 AM

@MAFIA36790 Has this not been a problem before the election?

user116211

@orthocresol There was always a scattered protest against our reviews; but we didn't expect their airing of the grievances in the nomination page.

orthocresol

3:05 AM

0

Q: Beryl is a mineral which contains 5.03% Be, 10.4% Al, 35.5% Si and 53.58% O. What is the simplest formula for beryl?

So I tried to follow a 3 step rule to solving this equation: Divide each % by it's own atomic mass Dived each of those by whichever is smallest Find the lowest whole # Be = 5.03% / 9 = .558 moles Al = 10.04 / 26.98 = .372 moles (smallest number) Si = 31.35% / 32 = .979 moles O = 54.58%...

homework stoichiometry

I really wish we had a too localised close reason. And I regret answering this because it only encourages more of such questions.

Nobody learnt anything from this, except for two very lousy takeaways: 1) Your book is wrong 2) Press the buttons correctly.

Martin - マーチン

5:12 AM

@orthocresol lol... one thing i'd really like to add to the hw policy: Quote the source! In that case we at least know which books are false.

orthocresol

6:14 AM

@Martin-マーチン Heh, even Atkins has "incorrect" answers:

1

Q: Temperature dependence of reaction enthalpy

Estimate $\Delta_\mathrm{c}H^\circ(500\mathrm{~K})$ for methane by using the data given on the temperature dependence of heat capacities. $$\ce{CH4(g) + 2 O2(g) -> CO2(g) + 2H2O(g)}$$ My working First, heat capacities as functions of temperature. $$\begin{align} C_{p,m}(\ce{CO2}) &= 4...

homework physical-chemistry thermodynamics

The question specified to use data from the appendix, but the answer provided uses data from elsewhere in the text. Not quite incorrect, but led to a lot of head-scratching.

So, what can one expect from a textbook written for an exam syllabus, for example... They are quite often wrong (in my limited experience). :(

Martin - マーチン

@orthocresol At least Mr Atkins is often conceptually right. Filling in the numbers is just the last piece...

orthocresol

Worst case I remember off the top of my head, is this

well, this thing is somehow confusing link — user466672 Dec 8 '15 at 16:49

Quite a reputable text, as well. as.wiley.com/WileyCDA/WileyTitle/productCd-EHEP002932.html

Martin - マーチン

6:34 AM

It happens. Those books are written by people, people make mistakes. You can check one exercise a lot, if you do tens of thousands of them, you'll have a fowl one in there. A typo, a missed minus or plus ... so common. That's why you usually have a revision. It's pages like ours, that would help to correct such mistakes.

I think the erratum is one of the most important tags on the whole site

@orthocresol $\displaystyle \int\limits_{298\mathrm{~K}}^{500\mathrm{~K}} f(T)\mathrm{d}T$ \limits looks a bit better when you have such a long thing there... i think

orthocresol

Hmm, I didn't know you could do that o.o

Ooh, that's ten times nicer.

Martin - マーチン

6:56 AM

I always thought it would pich that by default for the display style, but I was wrong O.o

after all $\displaystyle \int_a^b$ typesets quite nice, but if you use real values it becomes a pain... integrals are quite always a pain though...

user228700

7:49 AM

Hello everyone :-) Is anybody especially familiar with the Lewis and Brönsted concepts of acids & bases..?

orthocresol

@KaumudiHarikumar What about it?

user228700

@orthocresol How are they the same and how are they different..?

orthocresol

8:23 AM

@KaumudiHarikumar Have you learnt the definitions? They are not the same thing at all. Perhaps the only thing they have in common is that they are both definitions of acids and bases.

user228700

@orthocresol We're having a discussion about this at the PSE chat(and not here :P). Can you please share your knowledge there? We're having a tough time :/

user228700

And yes, I have learned the definitions...

orthocresol

Sanya is correct; HCl is not a Lewis acid.

It is tempting to say that Lewis is a generalisation of Bronsted, and that is perhaps true to some extent (all Bronsted bases, which can accept protons by virtue of their lone pairs, are necessarily Lewis bases), but I don't think this works very well with the acids.

user228700

@orthocresol Yes! See, that! Can you elaborate that point a little more?

orthocresol

"Lewis is a generalisation of Bronsted because both involve donation/acceptance of electrons" - that is not correct at all. Bronsted theory deals with proton transfer.

HCl is not a Lewis acid. It can react with Lewis bases, but I would hesitate to call it a Lewis acid, because it does not have a low-lying empty orbital which can accept an electron pair from a Lewis base.

The reaction HCl + NH3 -> NH4Cl involves breakage of the H-Cl bond.

I would say that HCl is capable of generating a Lewis acid, i.e. H+, however HCl is not the Lewis acid in itself.

@KaumudiHarikumar So, I would agree with what you said - the sets of Lewis and Bronsted acids do overlap, but neither is a subset of another.

user228700

8:33 AM

@orthocresol Ah, I see!

user228700

Great!

orthocresol

It is probably a bit debatable. This is my stand on it though.

(Would be a good question for the main site, by the way :))

John Rennie

Hi

2

orthocresol

Ah - the legend himself.. :)

user228700

@orthocresol Oh, do you think I should post this..?

orthocresol

8:36 AM

@KaumudiHarikumar You may want to hear a second opinion. :)

user228700

@orthocresol Hm. But now that most of my confusion is gone, dunno what I'd ask :/

John Rennie

Seems like I arrived just in time for the discussion to be over :-)

orthocresol

@JohnRennie You are right. It is quite a petty distinction.

user228700

@JohnRennie Yes :P Also, I'll ping u here now onward, in case of doubts regarding Chem. Is that OK?

John Rennie

Just as well really as I specialised in physical chemistry. My recollection of the inorganic chemistry PhDs is that all looked like they had heavy metal poisoning :-)

orthocresol

8:39 AM

@KaumudiHarikumar Well, asking on main site will let future people benefit as well. It is a good question, one that I dealt with myself not-so-long ago as well.

user228700

@orthocresol While that may be, I still wanted to have it because I needed this to be crystal clear in my head because it's so important...

John Rennie

@KaumudiHarikumar I think you stop being pingable two days after you last visited a room, so unless you want to ping in the next two days it's probably best to ping me in the PSE. But I suggest that next time we immediately move here to continue the discussion.

user228700

@JohnRennie Yes, OK.

user228700

OK, you guys, thanks so much! :-) I'll try and post a question later today.

Martin - マーチン

9:33 AM

We are having elections! Do you have a question for the candidates? More information on meta.chem.se.

3

DHMO

What is hydrogen bond?

Is it covalent or ionic?

Wildcat

Neither, nor.

It is just a word to describe some orbital interactions in a molecule.

Dipole-dipole electrostatic interaction + donor-acceptor interaction.

orthocresol

Time to write up another self-answer! This time on org chem :D

Wildcat

@DHMO goldbook.iupac.org/H02899.html

Linux still sucks. Completely & terribly wrt to having different version of software side-by-side and supporting software which is few years old.

This is where Windows excels.

DHMO

@orthocresol i would be looking forward.

orthocresol

9:47 AM

Is it just me, or do a lot of organic chemists use OS X?

DHMO

@Wildcat thanks

Wildcat

@orthocresol Hi! Another? Is the one on HUP already written?

orthocresol

@Wildcat Mmhmm - chemistry.stackexchange.com/questions/59822

DHMO

Can anyone please look at what I said 10 hours earlier here? I cannot quote now.

@Wildcat

orthocresol

@orthocresol I was told that ChemDraw was originally produced for OS X, and that the Windows version was buggy - but I've never actually had issues on Windows...

Wildcat

9:51 AM

@orthocresol OS X is good OS, Macs are just too expensive for me right now. :| My old MacBook is slowly dying and is just too slow, so I replaced it with a PC.

DHMO

@orthocresol could you help me?

orthocresol

@DHMO What about?

DHMO

@orthocresol about what i said 10 hrs earlier. cannot quote now.

Wildcat

@DHMO, was it the question about tables for SALC?

orthocresol

@Wildcat I'm hoping that my current MacBook Pro can last awhile more. It's four years old this coming January but I really don't want to buy a new laptop

They are expensive!... I got my current one secondhand, so it was a little better :D

Wildcat

9:54 AM

@orthocresol my Air last for 5 years.

@DHMO, symbols in the first table here chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/…

orthocresol

Mine still seems quite OK, still pretty fast, so..

Wildcat

are the so-called irreducible representations of a point group

you need to know group theory pretty well to understand the SALC business...

Why do even bother about SALC?

Rubisco

@MAFIA36790 Physics?

Why would I be eligible for that?

Oh wait

HOLY SHIT

user116211

@Rubisco No.

Rubisco

OH NO OH NO OH NO

Wildcat

10:04 AM

LOL

Rubisco

This can't be happening

orthocresol

I love how everybody is so surprised :D

Rubisco

This shouldn't happen

user116211

@Rubisco Didn't you know that?

Rubisco

NOOOOOOOOOOOO

@MAFIA36790 Well, what does it seem like?

user116211

10:05 AM

@Rubisco My reaction?

Wildcat

@orthocresol @Rubisco would be surprised even more, once we tell him that we decided he is already participating. XD

orthocresol

@Wildcat Hahaha ;)

user116211

yesterday, by MAFIA36790

@Jan NO WAY!!

Rubisco

Rubisco is going to be killed by Mart since I didn't fulfill a problem . . . promise

orthocresol

yesterday, by Jan

Waitwot? We're having an election? O__O

Rubisco

10:07 AM

@JohnRennie Yo

user116211

@Rubisco One day guest ;P

orthocresol

yesterday, by orthocresol

Gosh, what, we are also having mod elections?!?!

user116211

We are insanely surprised at this ;))

Rubisco

I have something better to quote

Mar 22 at 13:30, by IͶΔ

Jun 14 '15 at 12:13, by M.A.Ramezani

So I'll nominate three years later, with a rep of 463846388274828k, and all of the badges, so I'll get a candidate score of 41/40.

user116211

@Rubisco ;P

Rubisco

10:11 AM

Wait

This isn't three years later . . . so I can still not run \o/

orthocresol

@Rubisco You figure it is better I leave that question out of the questionnaire?

Rubisco

@orthocresol It's a bit too big to be in an unformatted blockquote the candidates will answer.

It'd be really hard to follow, and make the already humongous candidate answers humongouserer

orthocresol

I'll repost on meta after elections, then.

Rubisco

It also merits a philosophical babble of itself

orthocresol

;)

Rubisco

10:14 AM

@orthocresol But it's tomorrow, before meta goes in exile

I mean the tomorrow of the elections

orthocresol

Huh?

Rubisco

I mean exactly after the elections end.

-1

Q: How to thicken salicylic acid solution without changing pH

Salicylic acid 17% w/w in vinegar (5% acetic acid) creates a clear liquid that has approximately the viscosity of water. I would like to thicken this liquid to a gel so it can stick to a surface of application without changing the pH. One preparation I saw included castor oil and nitrocellulose...

acid-base viscosity

This question was edited after it was closed. Should it be reopened? (more)

user116211

The question is.... Who will RUN then in the election?

orthocresol

@MAFIA36790 <---

Rubisco

Ron?

user116211

10:19 AM

@Rubisco Ah!

Rubisco

@orthocresol Noice

@MAFIA36790 He won't; I was just making a pun

user116211

@orthocresol I didn't do it in Physics and even after that I faced attacks; now imagine what would have happened if I went for a run..... now you are naming me?

Rubisco

@MAFIA36790 Sites usually boil like kettles around the elections

As Kit, one of ELU's mods said, elections are held to reduce mod work.

They actually increase it.

John Rennie

@Rubisco Hi :-) I am actually a physical chemist by training (solid state photochemistry then colloid science) but these days I've been seduced away by theoretical physics. I was just here briefly attempting to say something intelligent about Lewis acids.

user116211

@Rubisco yep T__T

user116211

10:22 AM

@JohnRennie \o/

DHMO

@Wildcat yes but what does a1 a2 b1 b2 represent?

Rubisco

Which brings me to the my question

user116211

As slereah says, @JohnRennie is a soap scientist ;P

Rubisco

. . . have mods experienced an increase in daily modding work?

@MAFIA36790 That's the only physicists I felt were useful

All the other ones make bombs and kill chemists. Out of spite.

orthocresol

@JohnRennie My tutor is also a colloid scientist. :)

user116211

10:23 AM

@orthocresol He is from Cambridge ;))

orthocresol

@MAFIA36790 WHAT? HOW DARE YOU MENTION THAT PLACE?

John Rennie

@orthocresol it's a wonderful area to work in because it's so varied and so relevant to everyday life. Though general relativity is fun, I think you'd have to say its impact on everyday life is pretty limited.

user116211

@orthocresol O.o

Rubisco

@MAFIA36790 This is an awkward Bollywoodian moment

Wildcat

5

Q: Symmetry labels for orbitals

What are the symmetry labels for the p and d orbitals of $\ce {[PtCl4]^{2-}}$ ? I understand the concept of symmetry labels for molecules. some explanation of how it applies to orbitals would be helpful.

homework orbitals coordination-compounds symmetry group-theory

user116211

10:25 AM

@Rubisco :(

Rubisco

@MAFIA36790 :!

DHMO

@Wildcat the labels are still unexplained?

user116211

@JohnRennie, tell them you were from Cambridge ;(

John Rennie

@MAFIA36790 Peterhouse for my degree then Jesus College for my PhD. Why, is the C word inflammatory around here?

user116211

Don't know ;/

Wildcat

10:27 AM

@DHMO do you know what irreps are?

orthocresol

@JohnRennie Nah, I'm from the other side, that's all haha

John Rennie

@orthocresol Oxford?

orthocresol

Mmhmm.

DHMO

@Wildcat not really...

Rubisco

O-word. O-word!

Please keep the conversation without any insults

Wildcat

10:28 AM

@DHMO well, then learn the group theory first.

orthocresol

I actually think Cambridge is a little more beautiful though. Although I may be biased, Oxford being a "working place" and Cambridge being more of a "holiday place" for me..

DHMO

@Wildcat I know what C2v means though

Somehow the labels are supposed to be elements of the C2v group?

orthocresol

the elements of the group are the symmetry operations, E, C2, sigma, sigma'

DHMO

then what are a1 a2 b1 b2...

orthocresol

irreducible representations

DHMO

10:29 AM

no visualization available?

Wildcat

In short, any two symmetry operations for a point group could be "combined" to give another symmetry operation of the same group.

DHMO

so abstract to me

orthocresol

It's really maths. a1, a2, b1, and b2 do not represent any specific object.

Wildcat

There are infinitely many ways to combine symm ops, and one "standard" way of doing it.

user116211

@orthocresol What made you conclude that I wonder ;)

Wildcat

10:31 AM

@DHMO visualization of irreducible representations?

Rubisco

@MAFIA36790 Cambridge people make more edible food

user116211

@DHMO; You should read Group Theory and Abstract Algebra a bit.

user116211

@Rubisco okay!

Rubisco

I was koking

DHMO

@Wildcat and then?

Rubisco

10:32 AM

i.e. kidding and joking

user116211

@Rubisco gotcha.

Wildcat

@DHMO If I say that A stands for a symmetrical rotation (around the principal axis) while B, to an asymmetrical does it helps with "visualization"?

DHMO

@Wildcat so A is basically C2?

Rubisco

@MAFIA36790 No you did not. I'm too small to catch

DHMO

what is asymmetrical?

Rubisco

10:34 AM

Something that isn't symmetrical

DHMO

can you specify which asymmetrical rotation are you talking about?

Wildcat

@DHMO ahhh... No. You have to read about group theory first.

orthocresol

@DHMO there's no shortcut to magically understanding character tables, without going through the requisite background.

DHMO

@orthocresol but I do understand C2v...

orthocresol

No you don't.

DHMO

10:35 AM

eh what

Wildcat

Look at the C2v character table then!

Consider the row that describes A1 irrep.

C2v E C2 σv(xz) σv'(yz)
A1 1 1 1 1

Rubisco

Did he accomplish in confusing you?

Wildcat

See, A1 is the representation of C2v group that is leaved unchanged when any symmetry operation is applied.

DHMO

what is a representation?

(sorry)

Wildcat

Thus, an orbital belong to A1 irrep if it is also leaved unchanged on any symmetry operation of C2v.

@DHMO a mathematical concept which could be hardly defined in common words.

I tried above.

user228700

10:38 AM

Hello again! :-) I was reading about the properties of water and came across the fact that the molarity of water if 55.55 M. I was wondering how it makes sense for us to talk about the molarity of water when it has nothing dissolved in it..? In this sense, we could talk about the molarity of literally anything. Help please..?

DHMO

@Wildcat Is representation a matrix?

orthocresol

@DHMO a representation is a set of matrices

one for each symmetry operation

DHMO

@orthocresol then what is the matrix for A1?

orthocresol

the character under each symmetry operation, is the sum of the diagonal elements of aforementioned matrices.

Wildcat

@DHMO representation describes a particular way how matrices that describes some symmetry operations of a point group are combined to form some other symmetry operations of the same group.

user228700

10:41 AM

@JohnRennie: Thoughts..?

orthocresol

@Wildcat i think we're just getting worse and worse..

Wildcat

@DHMO, seriously, all these doesn't make a lot of sense. Learn the group theory first.

Rubisco

@Wildcat Define . . . "."

John Rennie

@KaumudiHarikumar it's normally the activity of the water that matters not its molarity, and the activity is always 1.

Rubisco

Study group theory only to realize math isn't supposed to make sense

DHMO

10:43 AM

What is x^2 + y^2 supposed to mean?

orthocresol

I hope that CSE chat does not become a substitute for a series of university-level lectures.

Wildcat

@Rubisco you'd better start answering Q&A for candidates! :D We all here are counting on you!

Rubisco

You are counting on me?

user228700

@JohnRennie I questioned that a few days ago and ran into trouble so I'ma say "okay".

Rubisco

Then wildcats are about to become extinct

orthocresol

10:44 AM

@Rubisco Me too :(

DHMO

god i'm not even finished high school and i'm reading post-grad stuff

Rubisco

@KaumudiHarikumar Oh well, if you tell me my oxygenase sucks THEN U SUCK!!!!!!!!!!!!!!!!!!! Math people think of their theories like that

user228700

@Rubisco Um, what?

user116211

@DHMO Group theory is not a post-graduate topic, if you are talking about that ;)

Rubisco

Nathing

@orthocresol Nah, you're gonna run

orthocresol

10:45 AM

@DHMO There is nothing wrong with that, but at least trust us, who have been through these stuff, when we say that you need to read something properly from the ground up.

Rubisco

You're gonna save you paws

DHMO

@MAFIA36790 but irrep is?

orthocresol

@Rubisco Seals can't run.. We can only flop.

And roll around and be cute. `(.•.)´

user116211

@DHMO Not at all. But of course not high school stuff; but that's irrelevant.

Rubisco

@orthocresol And win hearts and not be hunted

DHMO

10:47 AM

@MAFIA36790 alright

user116211

@orthocresol The Iconic seal!!

DHMO

@orthocresol sure

Rubisco

OK OK

If you promise not to smooch me, I say yes

I'd run

orthocresol

@DHMO reddit.com/r/chemistry/comments/52lh92/…

Rubisco

I mean, it's gonna be some epinephrine

DHMO

10:48 AM

@orthocresol thanks

user116211

Jun 9 at 13:43, by Brian

Bishop's Group Theory and Chemistry

orthocresol

@Rubisco It's up to you, really.

Rubisco

Heh, but I don't think my candidate score even reaches 20

user116211

@DHMO check @hBy2Py's link above.

DHMO

@MAFIA36790 thanks

Rubisco

10:50 AM

@orthocresol I've spent the past two years telling that to people on different, unrelated occasions so don't you give me that

orthocresol

@Rubisco It's up to you, really.

Rubisco

@orthocresol IT'S UP TO YOU, REALLY

orthocresol

@Rubisco $\mathbf{It's\ up\ to\ you,\ really.}$

Rubisco

Of course it's not up to me

I have to save two species now.

And grow a mustache

Or prolly become bald

Or just Martin in a package

user116211

@Rubisco Martin has few hairs still left ;)

DHMO

10:53 AM

How do you guys remember the principles of different chemical cells...

Like, I am supposed to know that zinc-carbon cells use MnO2

orthocresol

@Rubisco It's 21, actually. data.stackexchange.com/chemistry/query/298418/candidate-score

Rubisco

@orthocresol O.O

I am genuinely surprised

But a site . . . I dunno

Hmm, with a candidate score of 21, I could manage to mod my laundry.

orthocresol

@Rubisco Mine is marginally higher, although it is only because of rep on main site.

Hahaha

Rubisco

@orthocresol This message is a self-righteous insult on all rep-farmers.

user116211

@Rubisco ;P

Rubisco

10:56 AM

33 mins ago, by Rubisco

. . . have mods experienced an increase in daily modding work?

user116211

Sep 14 at 15:59, by orthocresol

As for me, I am greedy for rep.................

Rubisco

I still wonder it at a rate of three wonders per minute

I haven't sensed an increased reviewing workload.

user116211

@Rubisco Maybe Mart needs more hands ;)

Rubisco

Well, obviously, last year we were playing with review balls like wildcats.

And this year we can haz a lot of CV reviews in one day

But that's that, I guess

Even these days, I feel the queues are emptier.

DHMO

Isn't dichromate toxic? Why is it used for testing alcohol in breath?

Rubisco

10:58 AM

That might only be because I'm usually absent these days

user116211

@Rubisco Mart is really busy too lately.

Rubisco

Really busy having fun

I nearly missed his visit to pH13.

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