Physical Properties Dimethyl ether vs ethanol

In summary, dimethyl ether and ethanol have different properties in terms of solubility in water and rate of evaporation. Due to the oxygen being bonded to 2 carbon atoms, dimethyl ether cannot form hydrogen bonds with water molecules and is therefore immiscible with water. In contrast, ethanol has a dipole due to the oxygen atom bonded to hydrogen, allowing it to form hydrogen bonds with water molecules and making it miscible with water. Additionally, dimethyl ether has weaker intermolecular forces (Van der Waal's forces) compared to ethanol's hydrogen bonds, causing it to boil at a lower temperature and evaporate more quickly at a given temperature. However, it should be noted that ether is not completely immiscible with
  • #1
trollcast
Gold Member
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Homework Statement


Explain the difference in the following properties of dimethyl ether and ethanol:

1) Solubility in water
2) Rate of evaporation

Homework Equations


The Attempt at a Solution



1) Due to the oxygen being bonded to 2 carbon atoms none of the hydrogen atoms in the dimethyl ether molcule have a dipole. This means that diethyl ether cannot form hydrogen bonds with the water molecules, this means the dimethyl ether is immiscible with water.

In ethanol the oxygen atom is bonded to a hydrogen which gives it a dipole, this allows the ethanol molecule to form hydrogen bonds with the water molecules and therefore it is miscible with water.

2) As noted above dimethyl ether cannot from hydrogen bonds. This means that the only intermolecular forces are Van der Waal's forces. These are weaker than the hydrogen bonds that can form between ethanol molecules. As both molecules have the same RFM this would imply that diethyl ether will boil at a lower temperature and therefore evaporate more quickly at a given temperature compared to ethanol.



I just wanted to check if my answers made sense and if I had used the right words in places.
 
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  • #2
trollcast said:

Homework Statement


Explain the difference in the following properties of dimethyl ether and ethanol:

1) Solubility in water
2) Rate of evaporation

Homework Equations


The Attempt at a Solution



1) Due to the oxygen being bonded to 2 carbon atoms none of the hydrogen atoms in the dimethyl ether molcule have a dipole. This means that diethyl ether cannot form hydrogen bonds with the water molecules, this means the dimethyl ether is immiscible with water.

In ethanol the oxygen atom is bonded to a hydrogen which gives it a dipole, this allows the ethanol molecule to form hydrogen bonds with the water molecules and therefore it is miscible with water.

2) As noted above dimethyl ether cannot from hydrogen bonds. This means that the only intermolecular forces are Van der Waal's forces. These are weaker than the hydrogen bonds that can form between ethanol molecules. As both molecules have the same RFM this would imply that diethyl ether will boil at a lower temperature and therefore evaporate more quickly at a given temperature compared to ethanol.



I just wanted to check if my answers made sense and if I had used the right words in places.

It makes sense.

Only one extra detail: ether is not totally immiscible with water. In fact depending on how it is made most ether will contain a little water. Dry ether will absorb water from the atmosphere unless prevented.

If you add water to ether or vice versa they mix till the ether is about 7%, then they separate into two layers; the ether layer contains some water and the water layer some ether.

So you have to think there is still some dipolar interaction between water molecules and the O of the ether.
 

Related to Physical Properties Dimethyl ether vs ethanol

1. What is the difference in boiling point between dimethyl ether and ethanol?

The boiling point of dimethyl ether is -24.9°C, while the boiling point of ethanol is 78.4°C. This means that dimethyl ether boils at a much lower temperature compared to ethanol.

2. Which compound is more flammable, dimethyl ether or ethanol?

Dimethyl ether is more flammable than ethanol. Its lower boiling point means that it can easily vaporize and form a flammable mixture with air. Ethanol, on the other hand, has a higher boiling point and is less likely to form a flammable mixture.

3. How do the densities of dimethyl ether and ethanol compare?

The density of dimethyl ether is 2.02 g/cm³, while the density of ethanol is 0.789 g/cm³. This means that dimethyl ether is more dense than ethanol, which can be attributed to its larger molecular weight.

4. Which compound has a stronger odor, dimethyl ether or ethanol?

Dimethyl ether has a much stronger odor compared to ethanol. This is because it has a lower molecular weight and can easily evaporate, releasing its strong odor.

5. Are dimethyl ether and ethanol soluble in water?

Both dimethyl ether and ethanol are soluble in water. However, ethanol is more soluble due to its ability to form hydrogen bonds with water molecules. Dimethyl ether, on the other hand, can only form weak dipole-dipole interactions with water molecules.

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