Question

Boiling point of ether is lower compared to alcohol having the same number of carbon atoms because:
A. there are no intermolecular H - bonds
B. there are no intramolecular H - bonds
C. oxygen atom is attached to the alkyl or aryl group
D. none of the above

Answer 1

Hint: The boiling point of the molecule depends on the type of intermolecular bond which is present between the different molecules. Firstly, we have to explain the formula of alcohol and ether and then about the bond present between the molecules.

Complete step by step solution:
- In the given question, we have to explain the reason behind the low boiling point of the ethers as compared to the alcohols.
- As we know that the boiling point of a molecule or substance is the temperature at which the vapour pressure of the liquid becomes equal to the atmospheric pressure.
- Now, alcohol and ether have a common formula of $\text{R-OH and R-O-R}$.
- Now, the boiling point of the molecules depends on the intermolecular force of attraction and there are three types of intermolecular force:
i) dipole-dipole interaction
ii) London dispersion force
iii) Hydrogen bonds.
- Among them, hydrogen is the strongest bond whereas London dispersion or Van Der Waals force is the weakest force.
- Because the hydrogen bonds are based on permanent dipoles and Vander Waals are based on the temporary dipoles.
- In alcohol, the hydrogen bond is present due to which it has strong bonds and needs more energy than the ether to break the bond.

Therefore, option A is the correct answer.

Note: Intra-molecular bonds are those bonds which are present within the molecule between the atoms. The boiling point of a molecule also depends on the temperature, branching and surface area of the molecule.