The Periodic Table - 2016-05-03 (page 1 of 2)

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12:13 AM

How easily lives are made complete here … But then, all I need is my target molecule and mine will feel soo~ much more complete.

4 hours later…

4:41 AM

@Jan said like a true organic chemist

Feeds meta.chemistry.se

0

Q: Can a bounty be applied to a year old answer?

Recently I came across the following question:- Fundamental forces behind covalent bonding Here, Terry Bollinger answered the question on July 1 2012. But recently someone bountied(right word?) the question, probably Jan on April 19 2016. And Terry's answer got the bounty on April 26 201...

user116211

5:12 AM

Why not? What rule does prevent someone to award bounty to old answers? If I like someone's answer and want to thank him apart from merely upvoting, I can put up a bounty on the question and award the bounty to the concerned answer. There can be many reason acting behind the purpose; but I'm sure there is no rule that bars us from doing this. — MAFIA36790 1 min ago

user116211

@Jan: You awarded the bounty to Terry's answer for this, right?

5:30 AM

@orthocresol Are you sure about that?

user116211

@PhMgBr: o/

user116211

So early!

user116211

Your timeline is also telling the same....

6:30 AM

@orthocresol benzene on the dance floor

1 hour later…

7:36 AM

@PhMgBr Mmhmm yeah... I'm curious to find out how had is correct :)

user116211

hi @orthocresol....

user116211

I'm dying of seeing people screwing up Clausius' inequality thinking that it violates the Second Law.

user116211

morons ;(

8:12 AM

> We know that the CC atom in acetylene (H−C≡C−HH−C≡C−H) is spsp hybridised and so is more electronegative than alkenes or alkanes.

I wonder how sp hybridization makes carbon more electronegative in acetylene.

Interesting.

user116211

8:26 AM

@CowperKettle what is the percentage of s character in the hybridised orbital? Think about that.....

@MAFIA36790 I was at school.

user116211

@PhMgBr o.O

user116211

Time then?

@CowperKettle Hint: More s character in hybrid orbital means the electrons are closer to the nucleus.

@MAFIA36790 That? Exactly 10 a.m.

user116211

ooh....

8:34 AM

@orthocresol But I'm too lazy !!flip

(ノω・)ノ⌒゛◆

Hah, is he throwing a diamond AKA mod?

@PhMgBr thank you! quite interesting

@CowperKettle Note: The elctronegativities you see in the periodic tables are measured for neutral atoms.

user116211

@PhMgBr ;_;

8:36 AM

Less or more charge on the atom means more or less electronegativity.

nods

Look what I found:

An electride is an ionic compound in which an electron is the anion. Solutions of alkali metals in ammonia are electride salts. In the case of sodium, these blue solutions consist of [Na(NH3)6]+ and solvated electrons: Na + 6 NH3 → [Na(NH3)6]+,e− The cation [Na(NH3)6]+ is an octahedral coordination complex. == Solid salts == Addition of a complexant like crown ether or 2,2,2-cryptand to a solution of [Na(NH3)6]+e− affords [Na(crown ether)]+e− or [Na(2,2,2-crypt)]+e−. Evaporation of these solutions yields a blue-black paramagnetic salt with the formula [Na(2,2,2-crypt)]+e−. Most solid electride...

A salt with an electron as the anion.

Also @Cowp, as an ELLer that knows more than me, is this sentence grammatically correct?

> If you had any questions about the policies of our community, please ‎visit the help center.

user116211

@PhMgBr nope, IMO?

@PhMgBr I'm not sure.

Why, IYO?

@CowperKettle Yes, you're Cowper.

8:38 AM

A 'courteous' second conditional?

Dang it dude, why are you making me ask it on ELL? :'(

The use of had to imply that you, as a visitor, are very smart and are unlikely to have questions?

You might post this as a question on ELL

Leckon Chekon will be glad.

Hah

> One of the main advantages to the use of sodamide is that it is rarely functions as a nucleophile.

How come? An electron donor, a strong base, and not a nucleophile?

Sodium amide is an excellent nucleophile.

Hmm, that sentence is from Wikipedia, lemme see what it has written.

They prolly mean it rarely adds to compounds.

It usually gives off ammonia.

BUZZZ BUZZZ @Jan don't forget to award @Ortho in two days.

8:58 AM

> More electronegative elements are increasingly stable with the extra electron due to higher effective nuclear force of attraction.

Why is that? If the negative charge is tightly focused, that element will be unstable: it will attract protons actively.

That's why I did not upvote that answer.

@CowperKettle No, think of it the other way around.

If the atom is electronegative, it's more cozy with electrons around it.

0

Q: helo with resonance structure

need some help with finding resonance structures to this molecule, all the one I find do not obey octet, can someone help? I'll add the ones I made but I know they are not right and there is something I'm missing:

Hello with resonance structure?

9:13 AM

@PhMgBr It's a typo...He wanted to say "Halo with resonance structure"

@PhMgBr But isn't F(-) a stronger base than acetylene-anion?

> The order is of stability and hence also indicates the strength of these bases.

Fluorine is very electronegative

@CowperKettle No.

Hence the order does not indicate the strenght of these bases.

HF is a stronger acid than HCCH, so F- is a weaker base than HCC-.

F(-) attracts protons less actively than HCC(-)?

9:22 AM

The problem is you're looking at it qualitatively @Cowp. pKa let's you compare them quantitatively.

@CowperKettle Yes, since fluorine is pretty happy with its charge.

But if fluorine is more electronegative, all protons in the vicinity will crowd to connect to it.

Huh

It will attract all the protons, since it has such a big negative charge on itself, due to its high electronegativity

No, electronegativity means something crudely close to liking electrons, not being full of electrons.

So F(-) will have a lesser negative charge than HCC(-)? Why?

It stumps me.

9:26 AM

@CowperKettle No

Of course the charge density is more on fluoride.

But charge density isn't the only reason.

It would've been if you were comparing, like, C- and C 2-.

i.e. the same atoms.

But you're not.

I wonder what could be other reasons that make F(-) less attractive to protons

@CowperKettle It's because it's F. Halogens are pretty happy with their electrons.

They don't want a proton to come and disturb them.

But! The protons will hop on them!

Protons don't care whether the halogen is happy or not!

But! Let's measure an equilibrium constant.

You're wanting this to happen:

F- + H2O <=> HF + OH-

Yes.

9:30 AM

K_eq = 1/Kb(F-)

=Ka(HF)/Kw(H2O)

Which is 10^(-3.2)/10^(-14)

Which is a pretty large number.

Which means it happens close to completion.

Which doesn't make sense. Wait

It's Kb alright.

I should maybe eat this ice cream first.

Are your formulas right? I'll reread 'equilibrium constant' and water ionization constant then (the latter I never was able to grasp)

I remember reading it several times, and then giving up.

Maybe I should ask a question about this on the main site, you'll post these formulas.

Or would it be downvoted as being too simple?

I can explain it to you if you want. :)

@CowperKettle Read kinetics intro first, then equilibrium.

!!daily

22

Q: Differences between phenols and alcohols

I know phenols are more acidic as compared to alcohols, but are they considered different from alcohols? Sure, you can study something as a subset, but are phenols considered a subset of alcohols, or are they considered as completely different from alcohols? My confusion is due to the fact that ...

organic-chemistry alcohols

Bah, that's a boring question.

10:17 AM

@CowperKettle you are right, NH2- is nucleophilic, but it's so much more basic that it'll just react as a base first.

@CowperKettle also, think of it this way: both fluorine and carbon have an extra negative charge that they may or may not be entirely happy with.

that negative charge can be, to some extent, relieved by protonation, because HF and HCCH are both neutral molecules.

however, fluorine, being more electronegative, is happier to have that negative charge than carbon is

remember electronegative essentially means that it wants electrons, and electrons are negatively charged

On an unrelated note: does anybody have suggestions for interesting reactions? I just want an example to use for the ΔG question but I don't want to use the Haber process again...

11:07 AM

@orthocresol Thank you! So fluorine can exist in the anion form and despite there being hydroniums around, not be affected.

@CowperKettle mmhmm

11:20 AM

I'm reading about 'mass action law'. A fifth time. In a different source. Because I understand about 0% of it. Maybe a fifth reading will help.

Nope. Does not help.

user image

Why do we raise each term to the power of its molar coefficient?

Neither of the sources even mentions the reason.

Each description goes like "here are some obvious facts.. obvious facts.. more of them.. Kaboom! An unexplained formula."

11:47 AM

it's just how the maths works out

i'd say, just accept it for now, in the future you will see why it comes about

there should be a question on chem.SE explaining it thoug

h

i'll try to find it

I found some "historical" info in WIkipedia, but it's hard to understand. It nags me that I can't understand why it has those C and D to the power of their coefficients. (0:

Okay..

0

Q: In the Mass Action Law, why do we raise the molar concentration values to the power of the species' molar coefficients?

From ChemWiki: Why are the values [C], [D], etc. are raised to the powers of the species' molar coefficients?

Heh. (0:

I found this:

6

A: Why is the equilbrium constant expressed the way it is?

The answer is both. The formula for the equilibrium constant was first observed experimentally (that is, it's empirical) for many many reactions. Then it was justified theoretically in terms of what is now called the Gibbs energy. The reason the formula is multiplicative is that (very roughly) ...

I can't judge whether this is a true answer.

pH13 - Yet another Philipp

12:29 PM

@Brian afaik, it's written in grimme's paper about pbeh-3c, that it is implemented in orca and will be part of a future release

@Brian The new method was implemented into the ORCA and TURBOMOLE codes and will be available in the next releases. In ORCA, it is invoked with the compound keyword “pbeh-3c” while in TURBOMOLE, it is used as functional name.

12:49 PM

@orthocresol Maybe I have found that exact question. It's incomprehensible to me though. It's clear that one has to get some book on chem thermodynamics and read it first. Until then, one has just to memorize the formulas. (0:

I found this book: The Law of Mass Action

> A. B. Kudryavtsev, Reginald F. Jameson, Wolfgang Linert "The Law of Mass Action", 2001

I might be too dense to read it though.

@CowperKettle yeah, that's the question. Actually there's one more here: chemistry.stackexchange.com/questions/6924/… Sorry I had to go out just now and left it hanging... yes, until then you might just have to accept that that is how it is

1:48 PM

@pH13-YetanotherPhilipp haha, I must not've gotten to that point in the paper yet. :-)

1:59 PM

@CowperKettle In gases and liquids everything is just kind of bouncing around.

There are very many particles, so a statistical treatment of the system is suitable.

On average, any given thing in the system will collide with something else at a roughly constant rate (billions of times per second, typically).

So, take $\ce{A + B \stackrel{k_1}{->} C}$.

nods

For any given molecule of $\ce A$, the more of molecule $\ce B$ there is around, the faster the reaction will go.

As well, the more of $\ce A$ there is around, the faster the reaction will go.

So, $R_1 = k_1\left[\mathrm A\right]\left[\mathrm B\right]$.

It happens to work out that the "The more X, the faster the reaction" relationship is linear.

Now.

nods

Take a different reaction:
$\ce{A + A \stackrel{k_2}{->} D}$.

Which, equivalently, is:

$\ce{2A \stackrel{k_2}{->} D}$.

pH13 - Yet another Philipp

@Brian but I am waiting for that new version ...

2:06 PM

@CowperKettle So, going back to that rate expression,

$R_2 = k_2\left[\mathrm A\right]\left[\mathrm A\right] = k_2\left[\mathrm A\right]^2$.

By direct analogy

@pH13-YetanotherPhilipp Hells yah. DLPNO freaking everything.

nods

@CowperKettle Does that help?

@Brian I get the general idea.

Thank you!

this online TEX editor came in handy to see what your hyerogliphs meant. (0:

12

Q: MathJax in chat (ChatJax offshoot)

This is an offshoot of ChatJax, which enables MathJax along with mhchem on chat. Copy the text below: javascript:(function(){if(window.MathJax===undefined){var%20script=document.createElement("script");script.type="text/javascript";script.src="https://d3eoax9i5htok0.cloudfront.net/mathjax/lat...

discussion mathjax chat

@orthocresol Thank you!

2:11 PM

@CowperKettle D'oh! It did occur that you might not've had ChatJax enabled. Sorry!

No problem!

The same sort of philosophy applies to reactions with more reactants.

But you have to be careful, because it's very rare for any true elementary reaction to be more than second-order.

Most reactions that are more than a total of second order actually involve multi-step reactions.

So if molar coefficients are above 1, this is a second-order reaction?

2A + 5B + 12C --> D +E +F +G + H

Would be a 19-th order reaction

Second order in A

Fifth order in B

Twelfth order in C

19th order total

only if that's an elementary step of course

2:15 PM

@ortho No, that would still be the order

@Brian really?

You just can only infer the rate equation if it were actually elementary

Pretty sure

Autoxidation of NO is multistep:

@Brian i always thought the order was directly related to the indices in the rate equation

$\ce{2NO + O2 -> 2 NO2}$

@orthocresol Hm. Good point.

I want to say there's a dual-use to the term.

i.e. if the reaction is 2A + B -> C, but the rate eqn is r = k[A][B] then it's a second order overall

2:17 PM

But maybe not.

i'm not sure

Maybe the order of the reaction and the order of the kinetics can differ?

"xyz is a third-order reaction that follows second-order kinetics"?

The NO autoxidation overall reaction is third-order, though

$R = k\ce{[NO]^2[O2]}$.

So that's not a good example

I feel like I've used a phrase like, "The reaction as-written appears third-order, but ..."

I forgot what 'order of reaction' meant exactly, but remembered how it's roughly calculated.

user116211

@CowperKettle sum of the exponents....

user116211

remember?

2:25 PM

Yes, I've re-read that, but I don't understand the meaning of it anyway.

user116211

@Brian halp!

No, no need. (0:

user116211

ooh... damn, the session is about to begin; I can't continue here :((

Brian has already helped, I'm very grateful.

@MAFIA36790 See ya then!

BBL

@MAFIA36790 ?

1 hour later…

4:00 PM

> Al(OH)2Cl

Is it a "salt"?

yes, I would say so

A curious combination.

it's what one might call a mixed salt

An amphoteric hydroxide and a clorine

oh no, according to wiki it's called a double salt

4:10 PM

I thought a double salt should contain two "salty" residues like SO4(2-) or Cl(-)

isn't that exactly what your compound has

But "OH-" is a base residue, it's not from an acid

oh, i see

idk then

No problem! I'm just plowing through the textbook's chapter-end problems section. (0:

There's such an active Russian chem forum. I wonder if a Russian Chem StackExchange could be set up. But they blatantly answer homework questions there.

4:39 PM

It's strange. I calculate the pH of 0.001 M HCl solution and get 6. A YahooAnswers discussions says it's 3.

Ah. Got it.

@CowperKettle Pretty sure a double salt is any ionic compound (as opposed to a coordination complex) where either the cation side has two different cations, or the anion side has two different anions.

Potassium alum, potash alum, or potassium aluminum sulfate is a chemical compound: the potassium double sulfate of aluminium. Its chemical formula is KAl(SO4)2 and it is commonly found in its dodecahydrate form as KAl(SO4)2·12H2O. Alum is the common name for this chemical compound, given the nomenclature of potassium aluminum sulfate dodecahydrate. It is commonly used in water purification, leather tanning, dyeing, fireproof textiles, and baking powder. It also has cosmetic uses as a deodorant, as an aftershave treatment and as a styptic for minor bleeding from shaving. == Characteristics...

Chrome alum or Chromium(III) potassium sulfate is the potassium double sulfate of chromium. Its chemical formula is KCr(SO4)2 and it is commonly found in its dodecahydrate form as KCr(SO4)2·12(H2O). It is used in leather tanning. == Production and properties == Chromium alum is produced from chromate salts or from ferrochromium alloys. Concentrated aqueous solutions of potassium dichromate can be reduced, usually with sulfur dioxide but also with alcohols or formaldehyde, in the presence of sulfuric acid at temperatures <40 °C. Alternatively and less commonly, ferrochromium alloys can be dissolved...

@Brian I see! So OH(-) counts as an anion. Thank you!

yep

chem.lapeer.org/Chem1Docs/DoubleSalt.html

I believe double-anion salts are less common than double-cation salts, but I'm not sure.

@CowperKettle You can at least make chatroom in Russian...

@Freddy Just make sure you come up with a really clever name.

4:47 PM

Ru-chatroom maybe

"Markovnikov's"

"Great Mendeleev's Ghost"?

HCl's pH at 0.001 M is 3, meaning its dissociation is 100%.

How could there be stronger acids then?

Ah, probably they have more protons to shed

@CowperKettle Partly, but it's more that they're "more eager to get rid of" their protons.

According to the classical definition, a superacid is an acid with an acidity greater than that of 100% pure sulfuric acid, which has a Hammett acidity function (H0) of −12. According to the modern definition, superacid is a medium in which the chemical potential of the proton is higher than in pure sulfuric acid. Commercially available superacids include trifluoromethanesulfonic acid (CF3SO3H), also known as triflic acid, and fluorosulfuric acid (HSO3F), both of which are about a thousand times stronger (i.e. have more negative H0 values) than sulfuric acid. Strong superacids are prepared by the...

HSO4- is actually a weak acid

4:54 PM

When HCl dissociates, what it's actually doing is "pushing" its proton over onto water

$\ce{HCl + H2O -> Cl- + H3O+}$

They should really get latex up and running in these rooms

Water is pretty happy to get a proton pushed on it, in general.

3 hours ago, by orthocresol

12

Q: MathJax in chat (ChatJax offshoot)

This is an offshoot of ChatJax, which enables MathJax along with mhchem on chat. Copy the text below: javascript:(function(){if(window.MathJax===undefined){var%20script=document.createElement("script");script.type="text/javascript";script.src="https://d3eoax9i5htok0.cloudfront.net/mathjax/lat...

discussion mathjax chat

But eventually water will say "STOP, NO MORE!"

I tried that thing, it does not seem to work in Chrome

and then aqueous solution isn't a useful environment anymore for evaluating acidity

@CowperKettle I had to use Mart's answer to that question -- the code in the question itself didn't work for me either (I use Chrome, too), but Mart's answer's code did.

So, anyways, the experiments get pretty crazy to evaluate acidity

If water says "no more" that means that the acid will regain its H+

It has nowhere else to go

4:58 PM

But acids are ranked based upon, e.g., how strongly they "push" a proton onto other things.

(Or, how strongly they "rip" a pair of electrons off of other things; see Lewis acid)

@CowperKettle Yep

@Brian I'm having trouble with this mathjax thing

Just copy paste into the url?

Yep. I put "ChatJax" as the name, and pasted the script snippet into "URL"

(this is in the course of creating a new shortcut in my bookmarks bar)

"Your client has issued a malformed or illegal request"

OS/browser?

Mac OSX/chrome

5:02 PM

Hrmph. Got me, must be something OSX is grumpy about.

Works fine for me Win7/Chrome

Oh, it has just worked.

Chrome warned me that I'm trying to load something from an un-authenticated source, I clicked 'go ahead', and voila

Ah, yeah, it's suspicious of being asked to pull the MathJax code off of their site, probably.

This is weird... it turns out when I paste the text, the "javascript:" isn't pasted

When I type it and run it on this page it worked, though

Mm, yeah, the leading 'javascript:' is key.

Otherwise I think it'll try to load it as a webpage, which is nonsensical.

alright, I got it figured out

Thanks for the help @Brian

5:11 PM

Any time!

If we make a solution of CuSO4, Cu(2+) grabs OH- groups stronger, and SO4(2-) can exist, to an extent, without grabbing H+, and the solution will be acidic?

!!doubleflip/@orthocresol

ꞁosǝɹɔoɥʇɹo@╰(ﾟxﾟ)╯@oɹʇɥoɔɹǝsoꞁ

@CowperKettle Rigorously analyzed, this is actually rather complicated

@Brian H2SO4 is a strong acid, meaning SO4(2-) is a weak base, hence it will not rigorously grab H+

Hence, acidic solution

(0:

5:12 PM

Not quite true.

H2SO4 is a strong acid

HSO4- is actually a weak acid, pKa ~ 2

Cu(II) is actually also somewhat acidic.

I think you're right -- a solution of CuSO4 by itself would probably be slightly acidic

But: it's complicated.

Yay!

I'm not sure how to approach the system on an introductory chem level.

I can just post this as a main site question.

It would hopefully prompt some good answers, involving metal hydrolysis and the weak acid character of bisulfate.

CuSO4 solution is acidic

5:17 PM

What's up with Muhammad?

Doing the maths is not easy but the short answer is that Cu(2+) is more acidic than SO4(2-) is basic

I see his icon in the chat going up and down

Oh?

Maybe I'm burning some calories.

lol

The Ghost of @PhMgBr Past

er... "Present"

5:18 PM

Er, future.

0

Q: Why will CuSO4 solution be acidic?

An end-chapter problem posed in an 11-grade texbook asks to analyse whether a water solution of CuSO4 will be acidic. The standard answer is yes, because "$\ce{H2SO4}$ is a strong acid, hence $\ce{SO_4^2-}$ is a weak base. As a weak base, it will not be too hot about grabbing $\ce{H^+}$ from the...

@CowperKettle Uh-oh, I and my assertion have been associated with the question. WILL I BE PROVED RIGHT?!?!?!?!

@Brian I can shut down the question, If you want to. (0:

No, no!

Don't mind at all

I was just being dramatic for entertainment purposes.

(0:

5:32 PM

!!doubleflip/BRING ON THE ANSWERS!!

You forgot 'are you NOT entertained?'

¡¡sɹǝʍsuɐ ǝɥʇ uo ƃuᴉɹq╰(«○»益«○»)╯qɹᴉuƃ ou ʇɥǝ ɐusʍǝɹs¡¡

@Mith this didn't ping.

If you increase volume, you decrease pressure. That's it no pseudologic needed. also @aazz20 — Mithoron Dec 9 '15 at 17:45

The maximum bounty period is seven days, the minimum is one day. Bounties can be awarded to any answer. See the help centre. They are an additional way of marking a great answer. In the bounty dance this is also explicitly one option: meta.chemistry.stackexchange.com/questions/3030/… So if you see an excellent answer, but you cannot afford the bounty, create an entry there. (That would be nice. Thank you.) — Martin - マーチン ♦ 5 hours ago

@Mart when did you become British?

I hadn't noticed you wrote 'centre'.

Wait.

Is there anything more interesting to @Cowp's question other than hydrolysis?

sulfate/bisulfate equilibrium, potentially

pKa ~ 2

And any possible Cu(II)/sulfate or Cu(II)/bisulfate interactions

(would think those would be minor, though)

!!flip/bisulfate

5:41 PM

(۶ૈ‡▼益▼)۶qᴉsnꞁɟɐʇǝ

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Transcript for

May '163

The Periodic Table

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