Boiling point and connection distance of the elements

In summary, the boiling point of HF is higher than the boiling points of HCl, HBr, and HI due to the presence of hydrogen bonding. The connection distance, or boiling point, decreases as the atomic mass decreases in the order of HF, HCl, HBr, and HI. This is due to the decrease in electronegativity of the halogens and therefore a decrease in the bond polarity. Hydrogen bonding is a strong intermolecular force that affects the boiling point of a substance. To understand this concept better, it is recommended to watch videos or read texts on the topic from reliable sources such as Richard Feynman's Atoms in Motion.
  • #1
José Ricardo
92
5

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
 
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  • #2
José Ricardo said:
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)

José Ricardo said:
HF does hydrogen bond
You mean the intermolecular one, that too in an aqueous solution
 
Last edited:
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  • #3
How does the electronegativity of the halogens & hence the H-X bond polarity change down the group?
 
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  • #4
José Ricardo said:
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!
 
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  • #5
Also, the statement
José Ricardo said:
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
 
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  • #6
baldbrain said:
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.

baldbrain said:
How does the electronegativity of the halogens & hence the H-X bond polarity change down the group?

Yes, I made a mistake.

epenguin said:
Does not constitute an explanation, nor fits the data very well!

Yes, I don't know how to do this question.

baldbrain said:
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
José Ricardo said:
Could you recommend me a video lesson about this subject?
To begin with, watch this:
 
  • #8
@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
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.
 
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Related to Boiling point and connection distance of the elements

1. What is the definition of boiling point?

The boiling point of a substance is the temperature at which it changes from a liquid to a gas phase.

2. How is boiling point determined?

The boiling point of a substance is determined by the strength of intermolecular forces between its molecules. The stronger the forces, the higher the boiling point.

3. What is the relationship between boiling point and connection distance?

The connection distance of an element refers to the distance between its atoms in a solid state. The boiling point of an element tends to increase as the connection distance decreases, meaning that the atoms are closer together in a solid state.

4. How do the elements with the highest boiling points differ from those with lower boiling points?

Elements with the highest boiling points tend to have stronger intermolecular forces, such as metallic bonds or covalent bonds, compared to elements with lower boiling points that have weaker forces, such as van der Waals forces.

5. Can boiling point be used to determine the state of matter of an element?

Yes, the boiling point of an element can be used to determine whether it is a solid, liquid, or gas at a given temperature and pressure. If the temperature is above the boiling point, the element will be in a gaseous state. If the temperature is below the boiling point, the element will be in a solid or liquid state, depending on the temperature and pressure.

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