Is Fatty Acid Polar? 9 Facts You Should Know

In this article, we came to know about different facts fatty acids and find out is fatty acid polar or non-polar.

Fatty acids are the obtain from the foods that form building block of fats in our bodies. During the digestion process, fat will break down into simpler form fatty acids that will absorb into the blood. Fatty acids are both part polar as well as non-polar but as a whole it is considered as non-polar.

In the fatty acids, few molecules of carbon and functional group responsible for the polar nature of fatty acids. Polyunsaturated fatty acids were predominant in polar lipids.

Why are fatty acids non-polar?

As a whole fatty acid are still considered as non-polar because it is not dissolved in the water completely. The main reason for non-dissolving nature of fatty acids because fatty acids molecule make interaction with the water molecules.

The fatty acids molecule can make easily interaction with water molecule like it will do to other fatty acids. But the water molecule does not want to interact with fatty acids because it will have to rearrange itself around the fatty acid molecule to form hydrogen bond which require lots of entropy. The extra entropy make Gibbs Free Energy change unfavorable.

Is fatty acid polar
Saturated fatty acid from Wikipedia

Which end of a fatty acid is polar and hydrophilic?

Fatty acids have mainly two parts: carboxylic acid part and fat part. The carboxylic acid part of fatty acids is hydrophilic(water loving) i.e. attract water molecule to the fatty acids. The fat part is made up of hydrocarbon due to which it is hydrophobic (repel water molecule) in nature.

The carboxylic group of fatty acid is present at the head and chains of carbon molecule formed its tail part. Thus, the head part is hydrophilic and tail part is hydrophobic in nature.

Why is the head of a fatty acid hydrophilic?

The head of fatty acids is made of carboxylic group -COO, which is negatively charged. Due to presence of charged molecule at the head position of fatty acid, it will attract the water molecule to itself to form the hydrogen bond with water molecule.

Water molecule can easily interact with H-element of water with carboxylic group -COO of fatty acid and form strong H-bond. Thus, behave as hydrophilic means water loving end of fatty acid.

Why is the head of a fatty acid polar?

The head of the fatty acid is made of carboxylic group having negative charge. The negative charge presence makes the head part of fatty acid polar as it attracts the hydrogen element of water very easily.

Due to negative charge present on the -COO group, the outer electron spin around the nuclei of atoms that are not distribute evenly. The mass of oxygen atom is relatively higher than carbon atom so electron take more time in the vicinity of oxygen atom.

Is a fatty acid tail polar or non-polar?

Fatty acids have tail made up hydrocarbon chain where the charge is evenly distributed that is why fatty acids are non-polar in nature. Due to its non-polar nature, it is hydrophobic (do not dissolve in nature).

The non-polar fatty acid “tail” consists of three hydrocarbons having a polar carboxyl functional group. As the rule, ‘like dissolve like’ the hydrophobic end does not dissolve in water but hydrophilic head of fatty acid like to dissolve in water.

Why are fatty acid tails nonpolar?

The fatty acids chains are the uncharged, non-polar tails which are hydrophobic. Due to hydrophobicity, they repeal water molecules. The tail will face toward the inside and away from the water and meet in the inner region of the membrane.

When the phospholipid placed in the water, they grouped together to form micelles that is arrange each other in a spherical form on the aqueous solutions.

What functional group on the fatty acid is polar?

Carboxylic acid group present at the head position of fatty acids are polar in nature. -C=O group of carboxylic groups are uncharged, polar that is having partial positive and partial negative charges.

Due to its charged molecules, the carboxylic group attract the hydrogen molecule of water to itself and able to dissolve itself in the water. Carbon atom is lighter than oxygen atom in the carbonyl compound and hence chare is unevenly distributed over carbon and oxygen atom, thus attain the polarity.

What is the functional group in a fatty acid?

Fatty acids molecule composed of long chain of hydrocarbon molecules that have carboxylic acid functional group. Carbon chain are either saturated and unsaturated in nature.

When the three chains of fatty acids are attached to glycerol molecule formed a lipid molecule. E.g. Steric acid is a saturated fatty acid, only single bond is present between the C-C atoms. Linoleic acid is the example of unsaturated fatty acid.


To wrap the article, we stated that fatty acid has both polar and non-polar end but it is overall uncharged and non-polar in nature. It is not able dissolve in water hydrophobic but can easily dissolve in non-polar solvent like glycerol.

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