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

In summary, the boiling and melting points of ethane and formaldehyde differ despite having similar molecular weights due to stronger intermolecular forces, such as hydrogen bonding and dipole-dipole interactions, in formaldehyde compared to only London forces in ethane.
  • #1
whit88
3
0
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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  • #2
what kinds of compounds are you talking about?
 
  • #3
ethane and formaldehyde
 
  • #4
what's the structure of formaldehyde? I forgot.
 
  • #5
does this have to do with intermolecular interactions?
 
  • #6
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.
 

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

1. What is molecular weight?

Molecular weight refers to the mass of a molecule, which is determined by adding up the atomic weights of each atom in the molecule. It is measured in atomic mass units (amu) or grams per mole (g/mol).

2. How is molecular weight related to boiling point (BP) and melting point (MP)?

The molecular weight of a substance is directly related to its boiling point and melting point. Generally, substances with higher molecular weights have higher boiling points and melting points due to stronger intermolecular forces between the molecules.

3. Can molecular weight be used to predict the BP and MP of a substance?

Yes, in most cases, the molecular weight of a substance can be used to predict its boiling point and melting point. However, other factors such as molecular structure and intermolecular forces may also affect the BP and MP.

4. How does the molecular weight of a substance affect its physical and chemical properties?

The molecular weight of a substance can greatly influence its physical and chemical properties such as solubility, density, and reactivity. Substances with higher molecular weights may have stronger intermolecular forces and therefore exhibit different properties compared to substances with lower molecular weights.

5. How is molecular weight calculated?

Molecular weight is calculated by adding up the atomic weights of each atom in a molecule. This information can be found on the periodic table, and the total molecular weight is usually expressed in atomic mass units (amu) or grams per mole (g/mol).

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