Why do molecular weight and BP/MP differ in formaldehyde and ethane?

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Discussion Overview

The discussion centers on the differences in boiling and melting points of formaldehyde and ethane, despite their similar molecular weights. Participants explore the underlying reasons for this discrepancy, focusing on molecular structure and intermolecular interactions.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant notes the significant difference in boiling and melting points between formaldehyde and ethane, despite their similar molecular weights.
  • Another participant questions the types of compounds being discussed, clarifying that they are ethane and formaldehyde.
  • A participant inquires about the structure of formaldehyde, indicating a need for clarification on its molecular characteristics.
  • There is a suggestion that the differences in boiling and melting points may relate to intermolecular interactions.
  • One participant proposes that stronger intermolecular forces, such as hydrogen bonding and dipole-dipole interactions in formaldehyde, contribute to its higher boiling and melting points compared to ethane, which only exhibits London dispersion forces.

Areas of Agreement / Disagreement

The discussion includes multiple viewpoints regarding the role of intermolecular forces, with some participants suggesting that these forces explain the differences in boiling and melting points. However, there is no consensus on the specifics of the molecular interactions or their implications.

Contextual Notes

Participants have not fully explored the molecular structures or provided detailed definitions of the intermolecular forces involved, leaving some assumptions unaddressed.

whit88
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While both molecules have a very similar molecular weight, their boiling and melting points vary significantly. Explain the behavoir.


i have look everywhere to try and figure out why the bp and mp are different from mw but i just can't get anywhere!
 
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what kinds of compounds are you talking about?
 
ethane and formaldehyde
 
what's the structure of formaldehyde? I forgot.
 
does this have to do with intermolecular interactions?
 
if it does, it's because stronger intermolecular forces occur between the different components of formaldehyde like hydrogen bonding, dipole-dipole interactions, and London forces while only London forces occur in between the different components of ethane, giving formaldehyde a higher boiling/melting point.
 

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