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Hot nitric acid (HNQ)
Hot nitric acid (HNQ)
3:01 AM
3
Q: Structure of pyrophosphorous acid

Ajay MishraWhat is the structure of pyrophosphorous acid? I asked this question here because the answer which I found on web and other resources are inconsistent which each other. For example, following data is given regarding the structure of pyrophosphorus acid in my textbook, which is not consistent wit...

inorganic-chemistry acid-base molecular-structure lewis-structure pnictogen
 
 
5 hours later…
Bounty Hunter
Bounty Hunter
7:39 AM
6
Q: Reason for the formation of azeotropes

AADHIWhy is it that some liquid mixtures (that exhibit positive/negative deviation from Raoult's law) form azeotropic mixtures at certain compositions? What is the physical reason behind this; are there any extra forces holding the two components together? If so, please elaborate on this.

physical-chemistry intermolecular-forces boiling-point vapor-pressure
 
 
3 hours later…
Avnish Kabaj
Avnish Kabaj
10:18 AM
Why is p-dichlorobenzene somewhat soluble but m-dichlorobenzene isn't despite m-dichlorobenzene being polar?
I answered that more hydrogen bonds can be formed as less steric crowding is present in p-dichlorobenzene
The examiner gave me full marks for that
But this seems to be 10/10 dubious to me
Halp?
 
Hot nitric acid (HNQ)
Hot nitric acid (HNQ)
10:51 AM
2
Q: Are pi electrons in 1,3 cyclobutadiene delocalised?

Shiladitya MukherjeeThe original question in my test was whether all bonds in the aforementioned molecule are of same length. According to the solution booklet, it is not because pi electrons are not delocalised due to anti-aromatic character. This seems a bit weird...

aromatic-compounds
 
 
5 hours later…
Mithoron
Mithoron
3:27 PM
@AvnishKabaj Their solubility is similarly bad. And there's no h-bonds to speak of.
 
YUSUF HASAN
YUSUF HASAN
3:59 PM
@Mithoron But still,if we have to compare.. What would be the argument?
 
Mithoron
Mithoron
@YUSUFHASAN You really think you can make everything out using few rules of thumb? This question ^ is dumb from the start.
 
YUSUF HASAN
YUSUF HASAN
@Mithoron Well... I won't comment on that,but it is asked in our exams for a qualitative comparison.. So i wanted to know what a valid argument(if any) would be.
If it is invalid then that's fine by me
 
Mithoron
Mithoron
Argument using what? Pi-stacking, hydrofobic effect, h-bonds with the ring, halogen bonds... ?
 
YUSUF HASAN
YUSUF HASAN
Umm... H-bonds and pi-stacking,maybe?
 
Mithoron
Mithoron
4:21 PM
Well, if you know enough about interactions of MOs of these compounds with each other and water, you can try. I could maybe try with local electron density and halogen bonds.
 
YUSUF HASAN
YUSUF HASAN
@Mithoron Okay,this seems out of my league... What about arguments based on hydrophobic effect?
 
Mithoron
Mithoron
@YUSUFHASAN If you can tell how entropy changes during solvation...
:D
I think one could say about the same what @AvnishKabaj but with halogen bonds
Halogen bond
A halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. == Bonding == Comparison between hydrogen and halogen bonding: Hydrogen bonding A ⋯ H − D {\displaystyle {\ce {A\cdots H-D}}} Halogen bonding A ⋯ X − ...
 
YUSUF HASAN
YUSUF HASAN
4:42 PM
@Mithoron Okay,this explanation works for me! Thanks a lot!
 
 
2 hours later…
Avnish Kabaj
Avnish Kabaj
6:40 PM
@Mithoron Thanks for this
 

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