How would you expect the melting point of eicosapentaenoic acid $\left[{\mathrm{CH}}_3{\mathrm{CH}}_2{\left(\mathrm{CH}={\mathrm{CHCH}}_2\right)}_5{\left({\mathrm{CH}}_2\right)}_2\mathrm{COOH}\right]$to compare with the melting points of the fatty acids listed in Table 31.2?

Numerous factors impact the melting point. Some of them include intermolecular attractions and symmetry.A molecule comprising greater intermolecular attractions comprises a more significant melting point.

Eicosapentaenoic acid (EPA) comes under the category of omega-3-fatty acids. The trivial name of this acid is timnodonic acid.Some sources of EPA include fish oil, breast milk, etc.

A particular category of fatty acid is unsaturated fatty acid. They comprise one or several C=C bonds. This can produce cis or trans isomers. An example of unsaturated fatty acid is oleic acid.

In table 31.2,arachidonic acid, fatty acid with a maximum number of carbon atoms, comprises 20 carbon atoms and four double bonds.The melting point of arachidonic acid is $-49°\mathrm{C}$.

The degree of unsaturation provides information regarding the number of double bonds. The melting point of fatty acid decreases with the degree of unsaturation.

The structure of eicosapentaenoic acid comprises 20 carbon atoms and five double bonds.So, the number of carbon atoms is similar for eicosapentaenoic acid and arachidonic acid.

But eicosapentaenoicacid consist of one more double bond than arachidonic acid.

Hence, the melting point of eicosapentaenoic acid is expected to be lower than arachidonic acid.