Chapter 7, Problem 7.21QP

Interpretation Introduction

Interpretation:

The polar molecules has to be found from the given set of options.

Concept Introduction:

Polarity is a term that is used to explain the separation of electric charge in a molecule.  A molecule is said to be polar if it contains atoms of different electronegativity bonded together.  Dipole moment is the measure of polarity of the molecule.  Dipole moment is the product of distance between the charges and the magnitude of electric charge, it is a vector quantity.  Even though a molecule is having atoms of different electronegativity bonded together if the geometry of the molecule is symmetric, then the resultant dipole moment cancels each other and the molecule becomes non-polar.

Water is an example of polar molecule.  From VSEPR theory the shape of the water is found to be bent.  The direction of dipole moment is given in the Figure 1.  Since the structure is not symmetrical the dipole is not cancelling each other.

Figure 1

The linear carbon dioxide molecule is an example of non-polar molecule that is having polar bonds.  Because of the symmetric structure the dipole moment cancels each other.

Figure 2