Hydrogen chloride (or HCl or hydrochloric acid) is a POLAR molecule.
But why?
And how can you say that HCl is a polar molecule?
Want to know the reason?
Let’s dive into it!
Hydrogen chloride (or HCl or hydrochloric acid) is a POLAR molecule because any two bonding atoms whose electronegativity difference is between 0.4 to 2.0 forms a polar bond.
Here in HCl molecule, the electronegativity difference of Hydrogen atom (H = 2.2) and Chlorine atom (Cl = 3.16) is 0.96 (i.e 3.16 – 2.2 = 0.96). This value (0.96) is between 0.4 and 2.0, hence the HCl molecule is a polar molecule.
Didn’t understand what is written above?
Let me explain this in a short and simple way (with 3D images).
You can also watch this short 2 minute video).
Why is HCl a Polar molecule? (Explained!)
HCl is a polar molecule because it has a partial positive charge (ẟ+) on the Hydrogen atom and partial negative charge (ẟ-) on the Chlorine atom.
In short, the HCl molecule forms a pole of positive charge and negative charge on it. Hence HCl is a polar molecule.
But wait, let me give you some detailed information about the polarity of HCl molecule.
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]
Now let’s come to the example of HCl molecule.
You can see the electronegativity values of Hydrogen (H) and Chlorine (Cl) atoms from the periodic table given below.
From the above image;
So for HCl, the electronegativity difference (ΔEN) = 3.16 – 2.2 = 0.96
This value lies between 0.4 to 1.7, which indicates that the bond between Hydrogen (H) and Chlorine (Cl) is polar covalent bond.
Hence, the Hydrogen chloride (or HCl) is a polar molecule.
How HCl becomes a Polar molecule?
In a HCl molecule, there is one hydrogen atom (H) and one chlorine atom (Cl). Both these atoms are covalently bonded with each other by sharing one electron pair between them.
If we compare the electronegativity of hydrogen and chlorine, then the chlorine is more electronegative than hydrogen.
This means that the chlorine atom has more tendency to attract the shared electron pair towards itself.
As the electron pair remains attracted towards the chlorine atom, the partial negative charge (ẟ-) appears on the Chlorine atom (Cl) and partial positive charge (ẟ+) appears on the Hydrogen atom (H).
In this way the partial positive and partial negative charges are generated on the HCl molecule and hence HCl becomes a polar molecule.
I hope you have understood the reason behind the polarity of Hydrogen chloride (i.e HCl) molecule.
See the polarity of other molecules to make your concepts clear:
Is BF3 Polar or Nonpolar?
Is H2S Polar or Nonpolar?
Is CH3Cl Polar or Nonpolar?
Is CF4 Polar or Nonpolar?
Is CH2Cl2 Polar or Nonpolar?
Jay is an educator and has helped more than 100,000 students in their studies by providing simple and easy explanations on different science-related topics. With a desire to make learning accessible for everyone, he founded Knords Learning, an online learning platform that provides students with easily understandable explanations.
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