Which substance has the highest boiling point?

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Discussion Overview

The discussion revolves around the boiling points of various substances, specifically comparing H2O, CO2, CH4, Kr, and NH3. Participants explore the factors influencing boiling points, including intermolecular forces and electronegativity, without reaching a definitive conclusion.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant asserts that H2O has the highest boiling point among the listed substances, initially considering NH3 due to its nitrogen-hydrogen bond.
  • Another participant questions what factors boiling point depends on, prompting a discussion about intermolecular forces.
  • Some participants clarify that boiling point is influenced by intermolecular forces rather than bonds, and inquire about the specific types of forces present in each molecule.
  • It is suggested that hydrogen bonding in water is the strongest among the substances discussed, with the electronegativity of oxygen contributing to this strength.
  • Participants note that water has two lone pairs of electrons, while ammonia has one, which may affect their respective boiling points.
  • There is a discussion about the number of possible hydrogen bonds in water and ammonia, with some suggesting that the difference in electronegativity is a key factor in determining boiling points.

Areas of Agreement / Disagreement

Participants express differing views on the factors affecting boiling points, particularly regarding the role of electronegativity and the strength of hydrogen bonds. No consensus is reached on the definitive reasons for the boiling point differences among the substances.

Contextual Notes

Participants have not fully resolved the implications of electronegativity and the types of intermolecular forces at play, leaving some assumptions about the relationships between these factors unaddressed.

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Of the following substances which has the highest boiling point?

H20, CO2, CH4, Kr, NH3

I already know the answer is H20 but I would've initially chosen NH3 because of the nitrogen bond to hydrogen but that's obviously wrong. Is it H20 because oxygen is more electronegative then nitrogen??
 
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What does boiling point depend on?
 
intermolecular bonds
 
More like forces (van der Waals forces are not classified as bonds). OK, what kinds of intermolecular forces & bonds will be at work in each molecule? Which of these are the strongest?
 
The hydrogen bonding between molecules in this case is the strongest.
Oxygen being more electronegative than nitrogen will form stronger hydrogen bonds.
Also water there are 2 lone pairs of electrons whereas the nitrogen in NH3 has only 1 lone pair of electrons.But ,correct me if I am wrong , in water, there are 4 possible hydrogen bonds (2 from oxygen and 2 from hydrogen) and in ammonia there are also 4 possible hydrogen bonds (1 from nitrogen and 3 from hydrogen).
So the only difference is then the electronegativity of oxygen which determines the boiling point?
 

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