March 28, 2024, 01:46:40 PM
Forum Rules: Read This Before Posting


Topic: Hydrogen bonds - Strong or weak?  (Read 21026 times)

0 Members and 1 Guest are viewing this topic.

Offline neobenzene

  • Regular Member
  • ***
  • Posts: 56
  • Mole Snacks: +1/-3
Hydrogen bonds - Strong or weak?
« on: August 12, 2012, 12:00:12 AM »
Hi! I have this major, basic doubt. Is intermolecular hydrogen bonding strong or weak? I have always been taught in school that they are "strong" bonds, but I came across this video on YouTube recently which states that they are "weak" bonds.

Which one is right?

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: Hydrogen bonds - Strong or weak?
« Reply #1 on: August 12, 2012, 02:16:08 AM »
Hi! I have this major, basic doubt. Is intermolecular hydrogen bonding strong or weak? I have always been taught in school that they are "strong" bonds, but I came across this video on YouTube recently which states that they are "weak" bonds.

Which one is right?

A quote from a Wiki page:
"The hydrogen bond (5 to 30 kJ/mole) is stronger than a van der Waals interaction, but weaker than covalent or ionic bonds. This type of bond occurs in both inorganic molecules such as water and organic molecules like DNA."
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline neobenzene

  • Regular Member
  • ***
  • Posts: 56
  • Mole Snacks: +1/-3
Re: Hydrogen bonds - Strong or weak?
« Reply #2 on: August 12, 2012, 02:23:58 AM »
But are hydrogen bonds strong enough to raise the melting/boiling points of a molecule?

Offline DrCMS

  • Chemist
  • Sr. Member
  • *
  • Posts: 1296
  • Mole Snacks: +210/-81
  • Gender: Male
Re: Hydrogen bonds - Strong or weak?
« Reply #3 on: August 12, 2012, 04:30:37 AM »
Yes and water is the classic example.

Offline neobenzene

  • Regular Member
  • ***
  • Posts: 56
  • Mole Snacks: +1/-3
Re: Hydrogen bonds - Strong or weak?
« Reply #4 on: August 12, 2012, 04:49:33 AM »
So does that mean, NaI, which is very covalent according to Fajan's rule, has very high melting/boiling points? And by this, theoretically it should be more than that of water. Is that right?

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: Hydrogen bonds - Strong or weak?
« Reply #5 on: August 12, 2012, 05:41:24 AM »
So does that mean, NaI, which is very covalent according to Fajan's rule, has very high melting/boiling points? And by this, theoretically it should be more than that of water. Is that right?

Yes it has a much much higher MPt. and BPt. than water, and not just theoretically.
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline neobenzene

  • Regular Member
  • ***
  • Posts: 56
  • Mole Snacks: +1/-3
Re: Hydrogen bonds - Strong or weak?
« Reply #6 on: August 12, 2012, 09:43:27 AM »
Thank you very much, discodermolide and DrCMS!

Sponsored Links