The Periodic Table

12:09 AM

I have not used mhchem in "comments" thus far. Is it possible to be sure the code is correct prior to posting.

@user55119 not for comments; in my opinion the best way is to copy-paste your comment into the answer box and look at the preview.

hBy2Py

12:36 AM

@user55119 For short answers, since you've got 5min to edit before the comment is locked in, sometimes I'll just submit the comment, see how it renders, then edit the comment as needed.

Gaurang Tandon

1:22 AM

@orthocresol oh that's just so silly to forget :P

Abcd

5:36 AM

@GaurangTandon No idea why it has been closed as duplicate...

I have edited to explain how my ques is different.

Please vote to reopen if you agree.

Gaurang Tandon

@Abcd i need 3k rep

`> Why is ortho hydroxy benzoic acid $(pK_a = 2.98)$ more acidic than the para isomer $pK_a= 4.58$?

March's Advanced Organic Chemistry (7th ed) gives the reason to be intramolecular hydrogen bonding between the $\ce{OH}$ and $\ce{COO-}$ groups of the conjugate base.
However, note that **intermolecular** hydrogen bonding (between the $\ce{OH}$ and $\ce{COO-}$ of two *different* molecules) is possible in the *para* isomer. Interestingly, [this question][1] also states that intermolecular hydrogen bonding is relatively stronger than intramolecular one. So, shouldn't the para isomer be more ac…

@Abcd I suggest an edit to your question; so that it addresses the point; have a look and incorporate it into your quesion

once done, vote to reopen (I think you can vote to reopen on your own questions)

the previous question might have been closed because it might not have been clear at first glance what you meant

Abcd

@GaurangTandon i edited

Gaurang Tandon

@Abcd have a look at my edit above, it cuts to the point more clearly ---^

Abcd

@GaurangTandon you may add it

I will accept the edit.

Gaurang Tandon

@Abcd i don't wait for acceptance ;)

that's why I put it here before so you may have a look

anyways, now cast the reopen vote

Abcd

5:51 AM

@GaurangTandon done

Gaurang Tandon

@Abcd perfect; now sit back and let the system do its job :)

Abcd

@GaurangTandon why did you remove my edit?

The one that told the difference between that question

and my question

Gaurang Tandon

@Abcd oh, fixing

fixed. is it perfect now, @Abcd?

Abcd

6:10 AM

@GaurangTandon yup

Gaurang Tandon

great :)

Abcd

@GaurangTandon Did you learn the orders of I effect and M effect?

Gaurang Tandon

@Abcd it comes by practice; don't force

Abcd

Okay.

1,3-feeds

6:46 AM

0

Q: What is the need for [erratum]?

Tag: erratum Questions asked till date: 78 Tag wiki: For questions that deal with possible errors in a specific statement of a specified book, article, website, etc. These questions should always include a complete reference. My problem with this tag: what kind of a classification is it cre...

discussion

M.A.R.

7:00 AM

@1,3-feeds Erratum is the second, note the only meta tag considered useful

@Gau this means there's a new place you should check before posting about a tag. Meta

Meta Chem, not meta tag

That's something else

Gaurang Tandon

@M.A.R. i'd love to check in on a new place before posting but what's the "meta tag"?

M.A.R.

The Death of Meta Tags

Jeff Atwood on August 07, 2010

There are a few tags on Stack Overflow that have bugged me for a long time. Namely:

subjective

best-practices

beginner

But I could never quite articulate what, exactly, was wrong with these tags. It’s been bothering me more and more as time goes on. So much so, that about two months ago, I was compelled to ask on meta: Should we permanently remove the [subjective] tag?

There are some weak arguments in favor of keeping [subjective], but that’s about the best its proponents can muster. The arguments against it are much stronger. I felt Shog9 made the best case: …

Gaurang Tandon

the only meta discussion about erratum is very old and doesn't cover the cases I have thought of today (doesn't mean my thoughts are correct I might need some clarification) chemistry.meta.stackexchange.com/q/1661/5026

@M.A.R. interesting read

"The reason meta-tags are a problem is that they do not describe the content of the question." wow

bookmarked

Martin - マーチン

7:34 AM

4

Gaurang Tandon

@Martin-マーチン i'll ask again, it's the same problem as the RAS syndrome, right? "number of moles of x" should be "moles of x" instead? (serious question)

Abcd

Why does phenol not react with NaHCO3?

Gaurang Tandon

@Abcd because phenol is less acidic than h2co3

Abcd

@GaurangTandon = phenol is more stable than H2CO3?

Martin - マーチン

@GaurangTandon No, not really. Number of moles, or moles, should be amount of substance in moles. Just like mass in kilogram, force in newton, volume in liter. You don't use the unit to describe the quantity

Gaurang Tandon

7:43 AM

@Abcd why does stability come into play? phenol+nahco3->h2co3+sodium phenoxide; phenol is a weaker acid than h2co3, so the reaction shifts to the left (reactions favor formation of weak acids/weak bases)

Abcd

@GaurangTandon Weak acids are more stable, I read. Also, how do you remember the acidity order?

Gaurang Tandon

@Martin-マーチン oh great thank you finally resolved my confusion :D

@Abcd "Weak acids are more stable, I read" stable towards what? oxidation, nitration, basic attack,etc.? Moreover, it doesn't matter; you've to compare the acidity order here, not stability order

Abcd

@GaurangTandon stable wrt the potential energy diagram

Gaurang Tandon

@Abcd "how do you remember the acidity order?" practice, this is a very very very very common question

Rick

@Martin-マーチン Is it this correct: methanol is more acidic than water?

Martin - マーチン

7:46 AM

@GaurangTandon I even have a boilerplate for that:

Please note that the proper term for "(number of) moles" is [amount of substance](http://goldbook.iupac.org/A00297.html). The former would be the same as referring to the mass as "(number of) kilograms".

Gaurang Tandon

@Martin-マーチン cool, now it's my boilerplate too ;)

Rick

Some books say so, but they take the pka of water as 15.7

Abcd

7

Q: Is methanol really more acidic than water?

The question Why is methanol more acidic than water? deals with the reasoning of why methanol is more acidic than water. However, as mentioned in the comments of that question, the acidity constant of water is $14.0$, as confirmed by two sources$^{[1][2]}$, with one of them offering a very convin...

acid-base water alcohols

@Rick Forget about pKa

Martin - マーチン

@Rick I don't think so, not really sure though

Abcd

I will give you a more solid reason

Gaurang Tandon

7:48 AM

@Abcd can you give me a link to read? I never read about this before. Though I'll say again it doesn't matter in this question.

Abcd

@Rick ^

Gaurang Tandon

@Abcd you can link to the comment instead of pasting an image ;)

Abcd

Also, please accept it now. Methanol *is* more acidic than water.
Sources:
Stack Exchange Answer with two sub sources
Solomon Frhyle
Morrison Boyd
LG Wade

How many more proofs do you want @Rick :p ?

@GaurangTandon yup

@GaurangTandon Okay, then?

How does it prevent the reaction?

Gaurang Tandon

@Abcd a reaction is favored in the direction where weak acid/weak base forms; doesn't "prevent" per se but it means the direction in which the reaction will proceed in a majority

Abcd

@GaurangTandon "a reaction is favored in the direction where weak acid/weak base forms; ", reason?

Gaurang Tandon

7:55 AM

@Abcd never thought of that before; let me recall

Abcd

@GaurangTandon It does matter, see HOW TO predict the outcome of Acid and Base Reactions in Solomon Frhyle's book - 7th ed - page 89

Gaurang Tandon

@Abcd fine, will read by evening and let you know; quite surprising though

Abcd

We can explain it using $\Delta G^o = \Delta H^o - T\Delta S^o$ also.

Solvation leads to orderness and decrease in entropy

Martin - マーチン

@Abcd note that the o is a ring, i.e. \circ

Gaurang Tandon

@Abcd maybe, I don't know

Abcd

8:01 AM

$\Delta G^\circ$ is more positve for CH3CO2H and ClCH2CO2H because of this. Solvation of CH3CO2- is stronger

thus ch3co2h is weaker acid

@GaurangTandon Is nucleophilic addition to the carbonyl group there in 11th syllabus?

Gaurang Tandon

@Abcd i don't think so, only nomenclature+alkane/alkene/alkyne was taught to me in 11th

Abcd

@GaurangTandon its (= nucleophilic addition to the carbonyl group) there in 12th?

Gaurang Tandon

8:17 AM

@Abcd yep, it's there in extreme detail

Rick

Ok, I guess the answer is : it depends, in water no, in DMSO or in gaseous state, yes. But generally we take acidity in water..(as pka is defined from there)

But pka of water is 14 and not 15.7

Abcd

8:34 AM

@GaurangTandon:

5

A: Why is o-toluic acid (2-methylbenzoic acid) more acidic than benzoic acid?

Having one methyl group ortho to the carboxylate group will not prevent the carboxylate group from becoming reasonably planar with the aromatic ring. If you had a second methyl group in the other ortho position, then planarity would be a problem. A methyl group attached to a benzene ring is ele...

Can you read that answer? I wanted to ask something

Gaurang Tandon

8:46 AM

yes @Abcd ask

Abcd

@GaurangTandon He hasn't taken the SIR effect into account.

Gaurang Tandon

though I'll admit I was taught that methyl group makes -COOH non-planar and thus increases acidity cries

@Abcd yes, even I am wondering the same, "not taking into account" is the wrong word here; he has in fact bluntly discouraged SIR effect from being a factor

wait a sec

we need to come up with an example pair of acids that counter his point

(i've to go get lunch; will be back soon)

Gaurang Tandon

9:11 AM

yes, am back, trying to come up with examples

Abcd

@GaurangTandon first of all, why is it that benzoic acid is weak acid?

I know that there's resonance.

But there can be resonance in the deprotonated ion too

Gaurang Tandon

@Abcd benzoic acid is weaker than whom?

Abcd

@GaurangTandon ortho toulic acid

Gaurang Tandon

@Abcd ok, what doubt you have in ron's answer?

Abcd

@GaurangTandon first lets clear this confusion...

2 mins ago, by Abcd

I know that there's resonance.

1 min ago, by Abcd

But there can be resonance in the deprotonated ion too

Gaurang Tandon

9:15 AM

@Abcd yes so what?

Abcd

@GaurangTandon why does resonance make benzoic acid a weak acid?

Avatar Shiny

@Abcd Make the structures and you'll see yourself.

Gaurang Tandon

@Abcd in ron's answer, resonance is actually making o-toluidene a stronger acid than benzoic acid

Avatar Shiny

Delcocalizes the positive charge

@GaurangTandon SIR?

Abcd

@GaurangTandon yaa, that confused me even more...

Gaurang Tandon

9:23 AM

@Abcd why do you think it should make otoluidene weaker than benzoic?

@AvatarShiny ron discourages SIR

1,3-feeds

0

Q: A list of questions where the main question content is inside an image

Several questions like this or this have the main question content inside an image. I think this has several disadvantages: The content of images is not indexed and will not be found by a Google search by any future visitor, hence, that question adds no value to our site. The external image pro...

discussion

Avatar Shiny

@GaurangTandon Mithoron has commented that it doesn't explain why is o more than p

We were taught that CH3 is enough for SIR

Gaurang Tandon

@AvatarShiny that's true, lemme think

in fact, by ron's answer, we can say p-toluic acid is stronger than benzoic acid, as its conjugate is stabilized by hyperconjugation

Avatar Shiny

¯\_(ツ)_/¯

Gaurang Tandon

I will comment on ron's answer and wait for clarification; he generally always replies to confirmations

i agree with mithoron

i have commented; upvote my comment guys! chemistry.stackexchange.com/questions/20189/…

@Abcd @AvatarShiny Is it ok?

Avatar Shiny

9:41 AM

Just ask it on main

Faster

Gaurang Tandon

@AvatarShiny i'll wait

mhchem

10:02 AM

@GaurangTandon Yes. It is a bug, because I did not expect a newline character. I fixed it. (It will need some time to be visible here.) But now, it will show another error message ("missing open brace").

Gaurang Tandon

@mhchem thank you for your prompt fixing ^_^

mhchem

@GaurangTandon It was a 1-line fix and I was about to publish v3.3 anyway.

@LinearChristmas I am very late to the party. I cannot really figure out what the question was. Then the answer, most-probably is 42.

2

@GaurangTandon Thanks for reporting.

Gaurang Tandon

@mhchem welcome :)

Avatar Shiny

Oooooh 42

Abcd

11:43 AM

@GaurangTandon Please inform me when everything is sorted out... wrt that answer.

@GaurangTandon While making propene behave as an acid, which proton should we remove? I feel that the H joined to double bonded carbon should be removed...

Gaurang Tandon

12:05 PM

@Abcd you'll want the resulting carbanion to be the most stable...

Avatar Shiny

12:24 PM

@Abcd you go to fiitjee right ?

What was your AITS result?

Abcd

1:20 PM

@AvatarShiny didnt give this one, what was your rank?

Avatar Shiny

179

Abcd

@AvatarShiny woah! cool!

Avatar Shiny

@Abcd Thanks

Only 5K kids gave the test tho

Abcd

most students were busy with school exams...

i didnt give it coz of sylllabus

Zhe

3:08 PM

@Martin-マーチン Ah, yes. \\align is much better for formatting there

Martin - マーチン

happy to help ;)

Avatar Shiny

@Abcd There are like a trillion more left

Abcd

@AvatarShiny what

Abcd

3:33 PM

How does inhibition of resonance in ortho toulic acid make it more acidic than benzoic acid :( ?

Oh, nevermind. I figured it out myself!

Gaurang Tandon

First I crossed 2k rep and got rid of suggested edits review queue; but now the daily vote limit and daily flag limit is really annoying...arrgghh! I am being hindered from effectively doing a predetermined number of edits in a day, even though I have free time and +2k rep that's pointless as now I can neither flag nor upvote posts :(

Abcd

@GaurangTandon Who do you think will be more acidic? cyclohexanecarboxylic acid or 2 methyl cyclohexanecarboxylic acid?

My view is that cyclohexanecarboxylic acid should be more acidic

Because when the anion is formed in the 2nd compound's case, the +I effect of Methyl moiety will destabilise it.

Gaurang Tandon

3:50 PM

@Abcd yeah I think the first one; though again, note the answer by Klaus could be applicable here too

so I am not sure

Abcd

@GaurangTandon can I show you a mistake in MS Chauhan? Are you free for 5 minutes?

Gaurang Tandon

@Abcd yes show

give q number and chapter

Abcd

@GaurangTandon GOC, question 16

Gaurang Tandon

why doesn't stackexchange's detect this automatically as spam? chemistry.stackexchange.com/questions/91140/… how does it even get the pass

@Abcd what's wrong in this?

Abcd

@GaurangTandon SIR effect...

the first one's lone pair is readily available due to SIR

so it is more basic

Gaurang Tandon

3:58 PM

@Abcd where does the book mention "SIR effect", it reads "ortho effect" instead

@Abcd NO, read Klaus' answer I linked to

ortho effect in benzoic acid makes it a stronger acid

but ortho effect in aniline makes it a weaker base instead

Abcd

@GaurangTandon is it hydrogen bonding?

Gaurang Tandon

@Abcd as Klaus commented, it can be said to be a H-bonding, though it's not that common

Abcd

@GaurangTandon I like this answer more

Gaurang Tandon

@Abcd well i feel like it's open to speculation, since both answers have reasonable number of upvotes

you can abide by whichever answer you like

but only write in boards exam what NCERT says else marks will be lost (assuming CBSE board)

Abcd

@GaurangTandon ISC...

Gaurang Tandon

4:05 PM

@Abcd oh ok I forgot

probably Avatar was in CBSE

oh you guys are so confusing!!

Abcd

Now, another point is electron density lost due to interaction through H bond is more than electron density lost due to +M effect. @GaurangTandon

That's somewhat debatable

So the direct implication is H bond> M effect

Gaurang Tandon

you referring to Klaus' answer?

Abcd

Yup

Gaurang Tandon

I don't think Klaus is implying that electron density lost due to H-bond is more than that of +M effect

he just says that the lone pair of N atom is also involved in an "interaction" (sort of a poor man's H-bond I'd say) with the neighbouring methyl group

Abcd

@GaurangTandon well then why would anniline be more basic?

obviously because anniline has more available e- density

1 min ago, by Abcd

So the direct implication is H bond> M effect

Gaurang Tandon

4:11 PM

@Abcd because aniline's lone pair is only involved in reso; while toluidene's lone pair is involved in that reso throughout the ring as well as the H-bond interactions with neighbouring methyl

Abcd

@GaurangTandon Oh... I see. Nitrogen isn't perpendicular to the ring...

Avatar Shiny

@Abcd SiR doesn't take place SIP does

Both are ortho effects

Zhe

-5

Q: What fruits have electricity?

This is very important and as you guys help me I will help you with this

organic-chemistry

2

I really want to say Apple products have lots of electricity

4

Avatar Shiny

@Zhe I did it for you

Gaurang Tandon

@Zhe the cat is on a keyboard; so yeah that makes sense

Avatar Shiny

4:16 PM

-6

Q: What fruits have electricity?

This is very important and as you guys help me I will help you with this

organic-chemistry

Gaurang Tandon

@AvatarShiny what is SIP?

Avatar Shiny

Steric inhibition of protonation

MS Chouhan

Check

Once

I dunt have right now

Gaurang Tandon

@AvatarShiny Woah; never heard of that; give the page number when you can; i can't search through that big book so easily

Avatar Shiny

@GaurangTandon @Abcd you kids are got lucky

0

Q: Steric Inhibition of resonance vs. Steric inhibition of protonation

I want to know which out of Steric Inhibition of resonance(S.I.R) or Steric inhibition of protonation(S.I.P) is stronger/prevalent than the other. For example, when comparing basicities of o-Toluidine and Aniline Case 1(Using only S.I.R effect): We see that due the bulky methyl present on o-...

organic-chemistry aromatic-compounds resonance amines

Gaurang Tandon

wow that's cool; lemme read it

Apoorv Potnis

4:23 PM

@Zhe I'm satisfied with both your's and @orthocresol's answer. Is there any way to award half bounty to both?

Gaurang Tandon

@ApoorvPotnis if you're really looking for a "favor-both-situation", accept one answer and award the bounty to another; iirc there's no way to "split" it :P

Zhe

¯\_(ツ)_/¯

Gaurang Tandon

btw, you should wait till the end of the bounty period there's no need to hurry

@Abcd read this, the N atom is planar with the ring, as is toluic's COOH

Apoorv Potnis

Yeah. I won't award it right now. Probably wait a few more days.

Abcd

@GaurangTandon hmm

Isn't resonance possible in both methyl benzoic acid and benzoic acid after removal of H? @GaurangTandon

Then how does the former become more acidic.

I am gettttting confused again.

(Sorry, a bit frustated)

Gaurang Tandon

4:37 PM

ping me tomo; I gotta get some sleep now...

Zhe

methylbenzoic acid is not specific enough. I would imagine steric effects are important in o-methylbenzoic acid

Bounty Hunter

1

Q: How to account for the interface between two different phases in a discretized diffusion model?

I have tried to set up a model for the diffusion of a gas into a liquid. The two media are next to each other and the geometry is spherical because the system should simulate the diffusion out of a gas bubble. I have made a diffusion model for the gas phase (the left compartment) and a correspon...

reaction-mechanism diffusion

Abcd

@Zhe Sorry, I meant ortho methylbenzoic acid only

Whose symbol is $\Delta G^{+^+}$?

Nevermind, It means gibbs free energy at transition state.

Apoorv Potnis

5:13 PM

2

Q: How to account for the interface between two different phases in a discretized diffusion model?

I have tried to set up a model for the diffusion of a gas into a liquid. The two media are next to each other and the geometry is spherical because the system should simulate the diffusion out of a gas bubble. I have made a diffusion model for the gas phase (the left compartment) and a correspon...

reaction-mechanism diffusion

What mistake did I make in the suggested edit?

chemistry.stackexchange.com/review/suggested-edits/73832

Zhe

5:48 PM

@ApoorvPotnis I don't think other people can see rejected edits...

oh nm

Your link

M.A.R.

@Zhe of course they can

Zhe

@M.A.R. Yeah, I figured that out :/