What factors affect the boiling point of polar molecules?

In summary, the boiling point of the following compounds are arranged in the order of: methoxymethane<butane<pentane<water. However, after checking Wiki, it should be arranged as: methoxymethane<butane<pentane<water. This is because methoxymethane is a polar molecule and typically has a higher boiling point. Additionally, when considering boiling point, the polarization of molecules is a higher priority than molecular size. Ethers are generally nonpolar and have similar boiling points to alkanes of similar molecular mass. Dipole-dipole interactions are weak and do not significantly affect boiling point, with hydrogen bonding being the main factor. Carbon monoxide, which is isoe
  • #1
asdff529
38
0
arrange the boiling point of the following compounds
methoxymethane,butane,pentane and water
I quickly arrange like this
butane<pentane<methoxymethane<water
but after checking wiki,it should be
methoxymethane<butane<pentane<water
In my knowledge,methoxymethane is a polar molecule,so i should have a higher boiling point
Why,that it's not make sense?
Also which of the following has the higher priority when we are considering the boiling point, the polarization or the molecular size?
thanks!
 
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  • #2
The ether is only slightly polar, so the hydrophobic interactions of the longer alkenes are stronger.
 
  • #3
in general ethers can be regarded as basically nonpolar and have boiling points comparable to alkanes of similar molecular mass.

indeed have you noticed that the dipole-dipole interaction is extremely weak and doesn't really matter (in terms of phase change temperatures) in many cases, with only hydrogen bonding significantly altering the boiling point?

Carbon monoxide is isoelectronic with nitrogen N2, has the same mass, is much more polar than N2 yet they boil at almost the same temperature: 82 K vs. 78 K.

However, the dielectric properties of polar molecules are going to be different.
 

1. What is the boiling point of water?

The boiling point of water is 100 degrees Celsius or 212 degrees Fahrenheit at sea level.

2. How does altitude affect the boiling point?

As altitude increases, the atmospheric pressure decreases, causing the boiling point to also decrease. This is why water boils at a lower temperature at high altitudes.

3. Why is it important to know the boiling point of a substance?

Knowing the boiling point of a substance is important for various reasons, such as determining the appropriate cooking temperature for food or the boiling point of a solvent in a chemical reaction.

4. Can the boiling point of a substance be changed?

Yes, the boiling point of a substance can be changed by altering the pressure or adding impurities. For example, adding salt to water raises its boiling point.

5. How is the boiling point of a substance measured?

The boiling point of a substance is typically measured using a thermometer placed in the liquid that is being heated. The temperature at which the liquid starts to boil is recorded as the boiling point.

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