Question

6. Explain about van der walls interaction. Give an example to support your explanation.

7. Why CH4 molecule is not capable for hydrogen bond?

8. Discuss the properties of water that make it a good solvent and buffer.

9. Describe about amphipathic.

Answer 1

6) van der Waals' forces are forces that exist between MOLECULES of the same substance. They are quite different from the forces that make up the molecule. For example, a water molecule is made up of hydrogen and oxygen, which are bonded together by the sharing of electrons. These electrostatic forces that keep a molecule intact are existent in covalent and ionic bonding but they are NOT van der Waals' forces.

The van der Waals' forces are the forces that exist between the millions of separate water molecules, and not between the hydrogen and oxygen atoms in the case of water.

There are three types of van der Waals forces:

• Dipole-dipole forces : Dipole-dipole forces occur between molecules that have permanent dipoles.
• Dipole-induced dipole forces : A dipole-induced dipole attraction is a weak attraction that results when a polar molecule induces a dipole in an atom or nonpolar molecule.
• London dispersion forces : temporary force, only applies to non-polar molecules.