Is HOCl Polar or Nonpolar? (And Why?)

HOCl is a POLAR molecule.

But why? 

And how can you say that HOCl is a polar molecule?

Want to know the reason?
Let’s dive into it!

HOCl is a POLAR molecule because the O-H bond present in the molecule are polar and it has asymmetric geometry which causes the partial positive (ẟ+) and partial negative (ẟ-) charge to appear on the molecule. These ẟ+ and ẟ- charges are responsible to make the entire HOCl molecule polar.

Let me explain this in detail with the help of HOCl lewis structure and its 3D geometry.

Why is HOCl a Polar molecule? (Explained in 3 Steps)

HOCl is a polar molecule because it has poles of partial positive charge (ẟ+) and partial negative charge (ẟ-) on it.

Let me explain this to you in 3 steps!

Step #1: Draw the lewis structure

Here is a skeleton of HOCl lewis structure and it contains one O-H bond and one O-Cl bond.

(Note: If you want to know the steps of drawing the HOCl lewis dot structure, then visit this article: HOCl lewis structure, Or you can also watch this short 2 minute video).

So from the above diagram we have come to know that the HOCl molecule has one O-H bond and one O-Cl bond.

Now in the next step we have to check whether these bonds are polar or nonpolar.

And we also have to check the molecular geometry of HOCl.

Step #2: Check whether individual bonds are polar or nonpolar

The chemical bonds can be either nonpolar, polar or ionic depending on the difference of the electronegativity values (ΔEN) between the two atoms.

Have a look at the above image.

• If the electronegativity difference (ΔEN) is less than 0.4, then the bond is nonpolar covalent bond.
• If the electronegativity difference (ΔEN) is between 0.4 to 1.7, then the bond is polar covalent bond. 
• If the electronegativity difference (ΔEN) is greater than 1.7, then the bond is an ionic bond. ^{[1] [2] [3] [4] [5]}

Now let’s come to the example of HOCl molecule. It has one O-H bond and O-Cl bond.

You can see the electronegativity values of Hydrogen (H), Oxygen (O) and Chlorine (Cl) atoms from the periodic table given below.

From the above image;

• Electronegativity of Hydrogen (H) = 2.2 ^[6]
• Electronegativity of Oxygen (O) = 3.44 ^[7]
• Electronegativity of Chlorine (Cl) = 3.16 ^[8]

Now let’s see the polarity of each bond.

For O-H bond;
The electronegativity difference (ΔEN) = 3.44 – 2.2 = 1.24
This value lies between 0.4 to 1.7, which indicates that the bond between Oxygen (O) and Hydrogen (H) is polar.
Hence, the O-H bond is a polar covalent bond.

For O-Cl bond;
The electronegativity difference (ΔEN) = 3.44 – 3.16 = 0.28
This value is less than 0.4, which indicates that the bond between Oxygen (O) and Chlorine (Cl) is nonpolar.
Hence, the N-Cl bond is a nonpolar covalent bond.

You can see in the above image that because of higher electronegativity of Oxygen atom, the partial positive charge (ẟ+) appears on the Hydrogen atom (H) and partial negative charge (ẟ-) appears on the Oxygen atom (O).

But wait, we also have to look at the molecular geometry of HOCl to know whether it has a symmetric shape or not.

Step #3: Check whether the molecule is symmetric or not

Have a look at this 3D structure of HOCl. The Oxygen atom (O) is at the center and it is surrounded by Hydrogen atom (H) and Chlorine atom (Cl).

It also has one lone pair on the Oxygen atom (O).

Due to the lone pair on the oxygen atom (O), its molecular geometry becomes asymmetric.

So because of the polar O-H bond and asymmetric geometry, there are positive and negative poles of charges on the overall molecule of HOCl.

Hence, the HOCl molecule is a polar molecule.

I hope you have understood the reason behind the polar nature of HOCl molecule.

See the polarity of other molecules to make your concepts clear:
Is SiH3Br Polar or Nonpolar?
Is SeCl4 Polar or Nonpolar?
Is H2Te Polar or Nonpolar?
Is NH3 (Ammonia) Polar or Nonpolar?
Is CO2 Polar or Nonpolar?