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

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Molecular weight alone does not determine boiling and melting points, as seen in ethane and formaldehyde. Despite having similar molecular weights, formaldehyde exhibits higher boiling and melting points due to stronger intermolecular forces, including hydrogen bonding and dipole-dipole interactions. In contrast, ethane primarily experiences weaker London dispersion forces. This difference in intermolecular interactions is crucial for understanding the variance in physical properties. The discussion highlights the importance of molecular structure and interactions in determining boiling and melting points.
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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