Why ethyl have a low boiling point?

Answer 1

An ether has a lower boiling point than an alcohol of the same mass because of the stronger forces between the molecules in an alcohol.

At its boiling point, the forces of attraction between the molecules in a substance are no longer strong enough to hold the molecules together, because the molecules are moving with more and more energy. The stronger the intermolecular forces, the higher the boiling point.

All molecules will have some form of attractive 'Van der Waals' forces between them and if that were the only intermolecular force, then there would be very little difference between the alcohol and its corresponding ether.

In the case of the alcohol and the ether, both molecules also have polar bonds (the C-O bonds, for example), that lead to an electrostatic attraction between their molecules. This strengthens the intermolecular forces and causes an increase in the boiling point of both (compared to, for example, a pure hydrocarbon of the same mass).

The big difference is the presence of hydrogen bonds in the alcohol. Where a molecule has N-H, O-H or F-H bonds, hydrogen bonds may occur. These are far stronger (around 50kJ/mol) than other intermolecular forces (typically 1-5kJ/mol) and increase the boiling point. Hydrogen bonds are more than just a strong electrostatic attraction, they are a better described as a weak form of covalent bond (technically, they are three-centre, four electron bonds), and cause, for example, alcohols to have much higher boiling point than ethers of the same formula.

Answer 2

ethers and alcohals both are hydrocarbons but the difference in boiling points is because an alcohal contains OH group and due to this hydrogen oxygen bond there is a weak hydrogen bonding between the molecules of alcohals. so the molecules are held together and boling point is increased.

Answer 3

Ethanol actually has quite a high boiling point (78°C) considering it only has two carbons in its carbon chain. Ethane's boiling point is -89°C, ethene's -104°C, ethanal's 20 °C, etc.

It has such a high boiling point because it forms hydrogen bonds. Theses are relatively strong intermolecular forces caused by a slightly positive hydrogen atom on the -OH group being attracted to the slightly negative oxygen atom in the -OH group.

The same hydrogen bonding is why water has such relatively high boiling and melting points. Hydrogen bonding happens between hydrogen and nitrogen, fluorine and oxygen atoms. Chlorine, though electronegative, cannot hydrogen bond simply because it is too big.

Answer 4

Ethyl is not a known compound, so can't find the boiling point, not knowing what 'low' is to be.