IIT JEE , AIEEE Forum - Chemistry , Physical Chemistry - Hydrogen Bonding Question! Lets see who knows!!

Chemical_locha

We all know that a H-F molecule has intermolecular attractions with other H-F molecules by the phenomena called as Hydrogen Bonding..

H--F . . . H-F . . . H-F

But its not linear its at an angle

F
|
H.
     .
       . F
          |
          H.
               .
                  . F
                   |
                    H.
                       .
                         . F
                              |
                              H

Reasons please!! I promise lots of salutes to the one who gets it right.. Let me see who is the best chemist out there..

bhartibhanushali

116 degree

bhartibhanushali

i dont know the exact reason for that but i have read that somewhere

spideyunlimited

both hydrogen and fluorine atoms are very small , and inter electronic repulsions take place leading to angle strain

BALGANESH

the bond angle is 140 degree and in liquid and gaseous state it is linear

bhartibhanushali

but i read it as 116 degree

are u sure balganesh

BALGANESH

yes i am very sure

bhartibhanushali

http://en.wikipedia.org/wiki/Hydrogen_flouride

here also the angle given is 116

kundan_leo

good qs yaar................intriguing..........

LIKE BHARTI SAID IT IS 116 DEGREE FOR SURE............
BUT WHY????/.......THAT'S WHAT IS THE TRICK?????

IN MY BOOK IT SAYS THAT ITS A PHENOMENON OF TENSOR........

U KNOW THE GEOMETRICAL FIELD VECTOR........
AND FROM THE STRUCTURE OF HF , THE CRYSTAL LATTICE OF THE HYDROGEN FLUORIDE MOLECULEs ALIGNS ITSELF PARALLEL TO EACH OTHER ( SLIGHTL DEVIATED).....

AS A RESULT OF DIFFUSION OF THE HF MOLECULE ........
IT TAKES SUCCESSIVE OCCUPATIONS AT NON EQUIVALENT POSITIONS..........

that i guess is the possible explanation.........
i'd luv 2 know if any1 can explain it better..................c ya

BALGANESH

modern abc says 140 degree , have to refer other book to confirm

sid.shah.90

HF in solid state is in the form of zig zag chains.
The bond angle is 116^{o_{The shape is bent at F because of repulsion of bond and lone pairs in F..
Thus, max no of H bonds can be formed in bent shape with bend at F..
HF also exists as H}2F2 and H4F4 and so on, due to extensive H bonding...

Liquid HF has linear shape}

Chemical_locha

but whers the answer folks. the question my dear is that they are not parallel. They are inclined at an angle and i want the reason.. i know the reason its just that i am helping you learn.. and saalutes are promised... lets check out the best goiitian here..

Chemical_locha

@ BalGanesh.. sorry we are talking about the liquid state hydrogen bonding as well.. it is a highly viscous acid.. Come on people try.. the answer is very easy.. I know its notcoming to your minds.. dont argue about the angle.. argue about the explanation..

harsha_27

Hmmmm.......may be because the sizes of Flourine and Hydrogen are different,so it bends to decrease the surface area????May be for more compact structure????????????

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