[b1]

1. Hydorgen bonding can exist between identical molecules in which are pure substances?
ncl
nh3
h2
c2h6



 




 

[Albert]

http://www.chemicalforums.com/index.php?topic=58.0

[b1]

i believe the answer is h2 if not can you explain so i understand

[Dan]

Please use capital letters where appropriate for elemental symbols. Also use the sub and sup text formatting buttons. ie write H₂ not h2

Now, your answer is incorrect. I can see the cofusion, in that H₂ does consist of two H atoms bonded to each other, however, a Hydrogen bond is a bond beween a H-atom-bonded-to-an-electronegative-atom, and another electronegative atom. The electronegative atoms you have to worry about are F,O and N.

example. Water molecules are hydrogen bonded to each other. Here is a diagram of two water molecules hydrogen bonded together:

H-O-H---OH₂

the dashed line is the hydrogen bond

So here, the H I have highlighted in red is the "H-atom-bonded-to-an-electronegative-atom"
and the red O is the "another electronegative atom"

example number 2, hydrogen bonds can occur between two different molecules. I have chosen ethanol and water as an example:

CH₃CH₂O-H---OH₂

With this information, you should now be able to answer the question.

[b1]

Not sure if i'm right but is the correct answer C₂H₆

Edit: to properly format subscripts/superscripts mark part of the text you want to format, then click on ^sup or _sub button above edit field.

[wereworm73]

No, it's NH₃.  A C₂H₆ molecule does not contain any sufficiently electronegative atoms or lone electron pairs; so, no hydrogen bonding occurs between C₂H₆ molecules.  NH₃, however, has a nitrogen (one of the electronegative atoms Dan mentioned earlier) with a lone electron pair, and hydrogen bonding between NH₃ molecules occurs like this:

                     H
    ..               |
H-N-H - - - - :N-H
    |                |
    H               H

[b1]

As you can tell this is not my subject give me literature any day.
Thank you for your help