Lurkers, register with SgForums and ask ur H2 Chem qns here!
-
Originally posted by Flying grenade:
thanks !
then why need h2so4 or naoh with kmno4? why cannot kmno4 by itself or kmno4 with water?
Because of the oxidation reaction curved-arrow electron-flow mechanism required to carry out this oxidation. Go ask your school teacher or private tutor to show you. -
Hi Ultima, may i ask you,
https://www.dropbox.com/s/1ytc70wi31pu11c/20160329_152652.jpg?dl=0
Will this molecule have pi e- cloud? Nt sure because not uniform atoms, alternating N and P atoms instead of only C atoms
Can Si potentially form at Y? Theoretically, it could right? As period 3 element has energetically accessible vacant d orbitals. Then N atom can donate dative bond to Si?
In this case, is it P is more likely than Si, because form single bond more natural than dative bond ah (idk)??
-
Hi sir, can enquire your help on this,
https://www.dropbox.com/s/5gyb09xdknrbuuz/20160329_154547.jpg?dl=0
how to see if bond is more polar? (Option c)
Is polarity of bond due to the concept of electronegativity difference? Another factor is asymmetry or symmetry of molecule?
Option C : why a more polar O-H bond (compared to N-H bond) will result in stronger H bonding?
O is bonded to N and H, the N-O bond causes the O-H bond to be less polar, is it because delta -ve on O is reduced as it is bonded to N?
-
What are the factors affecting strength of Hydrogen bonding?
Is one of the factors electronegativity difference? E.g. H bond between 2 molecules which the H atom bonded to a F atom, is stronger than the H bond between 2 molecules which H atom bonded to O atom?
Are there anymore factors?
-
Originally posted by Flying grenade:
What are the factors affecting strength of Hydrogen bonding?
Is one of the factors electronegativity difference? E.g. H bond between 2 molecules which the H atom bonded to a F atom, is stronger than the H bond between 2 molecules which H atom bonded to O atom?
Are there anymore factors?
Formal charges affect strength of H bonding.And extensiveness (ie. number) of H bonds present are even more important than strength of individual H bonds.
-
Originally posted by Flying grenade:
Hi Ultima, may i ask you,
https://www.dropbox.com/s/1ytc70wi31pu11c/20160329_152652.jpg?dl=0
Will this molecule have pi e- cloud? Nt sure because not uniform atoms, alternating N and P atoms instead of only C atoms
Can Si potentially form at Y? Theoretically, it could right? As period 3 element has energetically accessible vacant d orbitals. Then N atom can donate dative bond to Si?
In this case, is it P is more likely than Si, because form single bond more natural than dative bond ah (idk)??
If it were dative bondings, formal charges must be indicated. Diagram did not indicate formal charges.Pi electron cloud present, but not uniformly distributed like benzene.
-
Originally posted by Flying grenade:
Hi sir, can enquire your help on this,
https://www.dropbox.com/s/5gyb09xdknrbuuz/20160329_154547.jpg?dl=0
how to see if bond is more polar? (Option c)
Is polarity of bond due to the concept of electronegativity difference? Another factor is asymmetry or symmetry of molecule?
Option C : why a more polar O-H bond (compared to N-H bond) will result in stronger H bonding?
Polarity of bonds are determined by charges and dipoles, which are turn determined by #1 - electronegativity, #2 -formal charges, #3 - resonance delocalization, #4 - hybridization of orbitals. -
Originally posted by UltimaOnline:
If it were dative bondings, formal charges must be indicated. Diagram did not indicate formal charges.Pi electron cloud present, but not uniformly distributed like benzene.
Thank you for all the explanation! !!
-
Originally posted by UltimaOnline:
Formal charges affect strength of H bonding.And extensiveness (ie. number) of H bonds present are even more important than strength of individual H bonds.
Wouldn't the formal charge on H atom,
that is connected to F,O,or N , all just be +1?
-
Originally posted by Flying grenade:
Wouldn't the formal charge on H atom,
that is connected to F,O,or N , all just be +1?
Wrong. Also, "+1" is how you describe OS (aka ON). "Unipositive" (aka "monopositive") is how you describe formal and ionic charges. -
Thanks for all this help on the proper phrasing! !!!!!
Isn't the formal charge on H unipositive?
T-T how to deduce "Formal charges affect strength of H bonding"?
-
Originally posted by Flying grenade:
Thanks for all this help on the proper phrasing! !!!!!
Isn't the formal charge on H unipositive?
Nope. Only protons, or H+ ions, have a unipositive formal charge = unipositive ionic charge. -
Originally posted by Flying grenade:
Thanks for all this help on the proper phrasing! !!!!!
Isn't the formal charge on H unipositive?
T-T how to deduce "Formal charges affect strength of H bonding"?
Ask your school teacher or private tutor. Inefficient to explain on forum. -
Is it magnitude of partial positive charge on H ?
-
Originally posted by Flying grenade:
Is it magnitude of partial positive on H ?
Yes correct, that's affected, which consequently and concordantly affects the strength of H bonds (or any type of bonds). -
Originally posted by UltimaOnline:
Yes correct, that's affected, which consequently and concordantly affects the strength of H bonds (or any type of bonds).Thanks for reply
Then why got formal charge one?
-
Partial charges are subsets of formal charges?
-
https://www.dropbox.com/s/y2r8umcix76epw3/Screenshot_2016-04-12-20-17-19.png?dl=0
How to know whether double bonds in rings can exhibit geometric isomerism or not? T___T..
-
With regard to (formal vs partial) charges, time to ask your school teacher or private tutor. Stop flogging the dead horse on this forum.
With regard to geometric isomerism, I'll only say this (so stop flogging dead horses, don't ask about this anymore), you're confusing ring geometric isomerism with ring alkene geometric isomerism. Ask your school teacher or private tutor for further details.
-
I've painstakingly found an article (difficult to find article about ring geometric isomerism) Cis/Trans Isomerism in Rings hidden within a webpage, jc students, i share with you ! :>
http://chemwiki.ucdavis.edu/Wikitexts/Purdue/Purdue%3A_Chem_26505/Chapter_3._Stereochemistry/3.9_Cis%2F%2FTrans_Isomerism
Ultima, as enriching as this article may be , it unfortunately does not address my persisting doubt about geometric isomerism about double bond in rings.
( this article elucidates about conformers, which exhibits isomerism about single bonds due to the particular orientation of the molecule, axial or equatorial )
I've learnt that,
- since that article does not talk about geometric isomerism about double bond in rings, perhaps there is none , or few
- I'll consult my tutor asap regarding which and when geometric isomerism can occur about double bond in rings (one of the factor is how large the ring is)
- there are yet more possible isomers , conformers/rotamers (lucky this not tested in A's)
Actually when i think now, about cistrans isomerism about a double bond in a ring, seems like it can't ??
I just visualise in my head, if a question ask why cistrans isomerism cannot occur (or can) about a double bond in a ring , i cant explain it in writing, purely anecdotal cos i just visualise in my head
It's just like, the double bond in the ring just can't do, cis-trans ,cos cannot rotate about that double bond in the ring *inserts voice and hand gestures *
-
-
Originally posted by UltimaOnline:
Yeah man , ikr, thanks! Took time to think and type out story
On a side note, this is also cool
http://www.dailymail.co.uk/news/article-3527999/A-bit-privacy-Angry-monkey-gives-middle-finger-photographed-morning-bath.html
It's like monkeys are so intelligent
-
https://www.dropbox.com/s/j7xc3rxzr1cxsk1/20160413_125416.jpg?dl=0
https://www.dropbox.com/s/q6jgofros9fv7sl/Screenshot_2016-04-13-13-07-33-1.png?dl=0
Why NO bond in hydroxylamine causes OH bond to be less polar?
I thought N is electronegative ,and the electronegativity difference between N and O will be less compared to electronegativity difference between O and H
The competition for electrons between N and O seems like a fierce one
it's like N would withdraw electrons by induction from O, causing O to be more electronegative , and should cause the OH bond to be more polar?
But O is more electronegative than N, so would suck electrons from N ,then why/how would then NO bond affect the OH bond at all?
Shouldn't be like if O attach to C atom,then would cause OH bond to be less polar?
Update :
N is also electronegative, and can pull some of the electron density of O atom, hence reducing the magnitude of partial negative charge on O,
So alkyl electron donating groups and adjacent electronegative groups can both reduce the partial negative charge on O??
-
Originally posted by Flying grenade:
https://www.dropbox.com/s/j7xc3rxzr1cxsk1/20160413_125416.jpg?dl=0
https://www.dropbox.com/s/q6jgofros9fv7sl/Screenshot_2016-04-13-13-07-33-1.png?dl=0
Why NO bond in hydroxylamine causes OH bond to be less polar?
I thought N is electronegative ,and the electronegativity difference between N and O will be less compared to electronegativity difference between O and H
The competition for electrons between N and O seems like a fierce one
it's like N would withdraw electrons by induction from O, causing O to be more electronegative , and should cause the OH bond to be more polar?
But O is more electronegative than N, so would suck electrons from N ,then why/how would then NO bond affect the OH bond at all?
Shouldn't be like if O attach to C atom,then would cause OH bond to be less polar?
The OH bond becomes less polar *compared to* if it was an R group (more electron-donating by induction) instead of an N atom (less electron-donating by induction, vis-Ã -vis O).If you still don't understand, go ask your school teacher or private tutor (I'm going to use this line on your incessant dead-horse-flogging questions from now onwards). Not all problems in life can be solved on a forum.
-
cool homework forum
Hi ultimaonline, regarding the discussion above, my thoughts are since N withdraws electron density away from O, wouldn't that cause O to have a even larger partial negative charge?
addendum : since electron density is been drawn away from O, it seems like O will have a smaller partial negative charge, as (relatively) less electrons around O atom compared to before? but wouldn't that cause, highly electronegative O to be more electron deficient, and thus want to bond to H more strongly, causing the OH bond to be more polar?