Describe the types of intermolecular forces that you think affect the properties of alkanes and the other functional groups of organic compounds discussed in this chapter. Solution Vander Waals forces- For hydrocarbons, like alkane molecules which does not have strong dipoles, Vander Waals forces are the only attractive forces between molecules. As the dipoles are nonexistent, it depends on contact between the molecules, or in other words the forces increase with surface area. Methane, a small molecule has very weak intermolecular forces, with a low boiling point. However, with increase in molecular weight, boiling point increases. This is because the larger surface area. Therefore, Vander Waals d ispersion forces increase with increasing molecular weight of the alkanes. Dipole-dipole interactions Compounds like acetone which has C=O group is polar compound because of the electronegativity difference between C and O. This results into the dipole-dipole interaction and increases the boiling point in comparison to the hydrocarbon, propane. Hydrogen Bonding This has a remarkable influence on the properties of organic molecules or for that matter in biological system. Compounds like ethanol which has an OH group exhibit extensive hydrogen bonding and its boiling point is much higher than the hydrocarbon Ethane. Hydrogen bond forms when H-atom is bonded to a very strong electronegative atoms, namely O, N, F and Cl etc. Based on the kind of inter molecular forces the solubility pattern of the organic compounds also changes. .

1. Describe the types of intermolecular forces that you think affect the properties of alkanes and the
other functional groups of organic compounds discussed in this chapter.
Solution
Vander Waals forces-
For hydrocarbons, like alkane molecules which does not have strong dipoles, Vander Waals
forces are the only attractive forces between molecules. As the dipoles are nonexistent, it
depends on contact between the molecules, or in other words the forces increase with surface
area. Methane, a small molecule has very weak intermolecular forces, with a low boiling point.
However, with increase in molecular weight, boiling point increases. This is because the larger
surface area. Therefore, Vander Waals d ispersion forces increase with increasing molecular
weight of the alkanes.
Dipole-dipole interactions
Compounds like acetone which has C=O group is polar compound because of the
electronegativity difference between C and O. This results into the dipole-dipole interaction and
increases the boiling point in comparison to the hydrocarbon, propane.
Hydrogen Bonding
This has a remarkable influence on the properties of organic molecules or for that matter in
biological system. Compounds like ethanol which has an OH group exhibit extensive hydrogen
bonding and its boiling point is much higher than the hydrocarbon Ethane.
Hydrogen bond forms when H-atom is bonded to a very strong electronegative atoms, namely O,
N, F and Cl etc.
Based on the kind of inter molecular forces the solubility pattern of the organic compounds also
changes.