Boiling point and connection distance of the elements

  • #1

Homework Statement


Explain the following order of the boiling point (° C)

HF (19.5)> HCl (-85.1) <HBr (-66.8) <HI (-35.4)

b) Explain the following order of connection distance (pm):

HF (92) <HCl (127) <HBr (141) <HI (161)

Homework Equations


xxx

The Attempt at a Solution


a) HF does hydrogen bond, and the others make ionic linking.
b) The lower the atomic mass, the higher the boiling point
 

Answers and Replies

  • #2
236
21
The lower the atomic mass, the higher the boiling point
This statement are wrong. (How?)
And the others make covalent linking, not ionic (generally means electrovalent in some texts)

HF does hydrogen bond
You mean the intermolecular one, that too in an aqueous solution
 
Last edited:
  • Like
Likes José Ricardo
  • #3
236
21
How does the electronegativity of the halogens & hence the H-X bond polarity change down the group?
 
  • Like
Likes José Ricardo
  • #4
epenguin
Homework Helper
Gold Member
3,828
858
HF (19.5)> HCl (-85.1) <HBr (-66.8) <HI (-35.4)


b) The lower the atomic mass, the higher the boiling point
Does not constitute an explanation, nor fits the data very well!
 
  • Like
Likes José Ricardo and baldbrain
  • #5
236
21
Also, the statement
HF does hydrogen bond, and the others make ionic linking.
makes it a bit ambiguous to know whether you've understood the concept of hydrogen bonding
 
  • Like
Likes José Ricardo
  • #6
This statement are wrong. (How?)
And the others make covalent linking, not ionic (generally means electrovalent in some texts)


You mean the intermolecular one, that too in an aqueous solution
Yes, you're right! Ionic linkings are stronger! The best example is our kitchen salt, which your trying to separate stove, you can't because the boiling point of the NaCl is 900 °C and only in industries is possible to separate the sodium from the chlorine.

How does the electronegativity of the halogens & hence the H-X bond polarity change down the group?
Yes, I made a mistake.

Does not constitute an explanation, nor fits the data very well!
Yes, I don't know how to do this question.

Also, the statement

makes it a bit ambiguous to know whether you've understood the concept of hydrogen bonding
I didn't even internalized this subject. Could you recommend me a video lesson about this subject?
 
  • #7
236
21
Could you recommend me a video lesson about this subject?
To begin with, watch this:
 
  • #8
236
21
@José Ricardo After watching that, you can guess that these molecules get 'associated' (get closer together due to attractions) with each other. Think, how will that affect the boiling point?
 
  • #9
403
36
I find that working out answers to questions like these are best done by starting with a particle level description (i.e., what the atoms or molecules are doing). An excellent written source for that is Richard Feynman's Atoms in Motion.

There are video's of Feynman informally talking about much of the material, like this and this. I find the text, though, more useful.
 
  • Like
Likes baldbrain

Related Threads on Boiling point and connection distance of the elements

  • Last Post
Replies
7
Views
10K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
3
Views
10K
  • Last Post
Replies
1
Views
9K
  • Last Post
Replies
1
Views
4K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
1
Views
7K
  • Last Post
Replies
5
Views
4K
Replies
2
Views
3K
  • Last Post
Replies
18
Views
6K
Top