Q.6.143 - An Introduction to General, Organic, and Biological Chemistry

Question

Classify each of the following molecules as polar or non-polar.

a. $\mathrm{HBr}$

b. ${\mathrm{SiO}}_2$

c. ${\mathrm{NCl}}_3$

d. ${\mathrm{CH}}_3\mathrm{Cl}$

e. ${\mathrm{NI}}_3$

f. ${\mathrm{H}}_2\mathrm{O}$

Step-by-Step Solution

Answer

a. Polar molecule.

b. Non-polar molecule

c. Non-polar molecule

d. Polar molecule

e. Polar molecule

f. Polar molecule

Step 1: Part (a) Given Information

To determine whether $\mathrm{HBr}$ polar or non-polar molecule.

Step 2: Part (b) Explanation

Hydrogen bromide is composed of hydrogen and bromine atoms. It is a diatomic molecule, where the atoms are connected via covalent bonds.

$\mathrm{HBr}$ is a polar molecule as one end is slightly positive i.e., $\mathrm{H}$ and the other end is slightly negative i.e., $\mathrm{Br}$. There is an electronegativity difference between Hydrogen and bromine atoms. Thus, making it a polar molecule.

Step 1: Part (b) Given Information

To determine whether ${\mathrm{SiO}}_2$ polar or non-polar molecule.

Step 2: Part (b) Explanation

Silicon dioxide is a non-polar molecule.  It is a linear as well as a symmetrical molecule.

A non-polar covalent bond is a bond that is formed when electrons are shared equally between two atoms. 

In ${\mathrm{SiO}}_2$ molecule, due to the opposite charges, the dipoles get cancel each other making the molecule non-polar.

Step 1: Part (a) Given Information

To determine whether ${\mathrm{NCl}}_3$is a polar or non-polar molecule.

Step 2: Part (b) Explanation

A non-polar covalent bond is a bond that is formed when electrons are shared equally between two atoms. 

Nitrogen trichloride is a non-polar molecule but it can be said that it is slightly polar due to the small electronegativity difference between nitrogen and hydrogen atoms.

Step 1: Part (d) Given Information

To determine whether ${\mathrm{CH}}_3\mathrm{Cl}$ is a polar or non-polar molecule.

Step 2: Part (d) Explanation

Chloroform is composed of carbon, hydrogen, and chlorine atoms.

Chloroform has a tetrahedral shape and is not symmetrical, this leads to the net dipole moment, making it a polar molecule. 

Step 1: Part (e) Given Information

To determine whether 3 is a polar on a non-polar molecule.

Step 2: Part (e) Explanation

Nitrogen triiodide is a polar molecule.

The lone pair present on the nitrogen atom generates repulsion between electron pairs due to which the structure turns to be bent in shape. causing a permanent dipole moment.

Step 1: Part (d) Given information

To determine whether ${\mathrm{H}}_2\mathrm{O}$ is a polar or non-polar molecule.

Step 2: Part (d) Explanation

Water is a polar molecule, as there exists an electronegativity difference between hydrogen and oxygen atoms. Due to the electronegativity difference, the molecule has a bent shape due to which there is a net dipole moment.