Why do stearic acid and oleic acid have different melting points?

Why do stearic acid and oleic acid have different melting points?

Both are saturated fatty acids but stearic acid (C18) has more molecular weight than palmitic acid (C16) hence more melting point. Molecular weight increases with number of carbons and hence chain length of the fatty acid. Therefore C18 fatty acids will have more molecular weight than C16 fatty acids.

Does stearic and oleic acid have a higher melting point?

Stearic acid has the highest melting point, followed by elaidic acid, and then oleic acid with the lowest melting point. Elaidic acid is a trans fatty acid, and the carbon chains can pack together almost as tightly as those of the saturated stearic acid.

Which has a lower melting point stearic acid or oleic acid?

Unsaturated fatty acids have lower melting points than saturated fatty acids of the same length. For example, the melting point of stearic acid is 69.6°C, whereas that of oleic acid (which contains one cis double bond) is 13.4°C. The melting points of polyunsaturated fatty acids of the C18 series are even lower.

What is the melting point of oleic acid?

Oleic acid is a solid with a low melting point; two crystalline forms (α-form, melting point 13.4 °C [56 °F], and β-form, melting point 16.3 °C [61 °F]) are known. It is a long-chain carboxylic acid; its molecule contains one double bond between C9 and C10 with the cis configuration.

Why does oleic acid have a high melting point?

The double bonds in unsaturated fatty acids all have the Z configuration. Thus, oleic acid (octadec-9-enoic acid) has the structure below. The cis-double bond introduces a kink, so the molecules cannot pack as neatly into a crystal lattice. The melting point of oleic acid is 14 °C.

Why does oleic acid have lower melting point?

Oleic acid is a cis fatty acid, and the bend in the hydrocarbon chain keeps these carbon chains from packing as closely together; fewer interactions lead to a much lower melting point. The shorter the carbon chain, the lower the melting point due to a decrease in intermolecular interactions.

Which fatty acid has the lowest melting point?

Unsaturated Fatty Acids. Note that as a group, the unsaturated fatty acids have lower melting points than the saturated fatty acids. The reason for this phenomenon can be found by a careful consideration of molecular geometries.

What is the difference between oleic acid and linoleic acid?

Oleic acid (omega-9, a monounsaturated fatty acid). Linoleic acid is lightweight and thinner than oleic acid, which means it is able to be absorbed by the skin more easily. Oleic acid, on the other hand, is thicker and feels rich, benefitting those with dry or aging skin.

Why does oleic acid have a low melting point?

Which acid has higher melting point?

Fatty Acids Natural fatty acids may be saturated or unsaturated, and as the following data indicate, the saturated acids have higher melting points than unsaturated acids of corresponding size. The double bonds in the unsaturated compounds listed on the right are all cis (or Z).

What is the difference between oleic acid and stearic acid?

Stearic is a saturated C 18 fatty acid whereas oleic acid is an unsaturated C 18 fatty acid. Saturated fatty acids will show different physical properties compared with unsaturated fatty acids of similar chain length. One of the important property is melting point. Two factors mainly influence melting point of fatty acids.

What is the difference between stearic acid and palmitic acid?

Both are saturated fatty acids but stearic acid (C 18) has more molecular weight than palmitic acid (C 16) hence more melting point. Molecular weight increases with number of carbons and hence chain length of the fatty acid.

What is the chemical name of stearic acid?

Stearic acid is an organic compound having the chemical formula C 17 H 35 CO 2 H. It is a saturated fatty acid having a carbon chain with 18 carbon atoms. The IUPAC name of this compound is octadecanoic acid. This acid appears as a white waxy substance. The salts and other derivatives of stearic acid are named stearates.

What is the melting point of linoleic acid?

Again common with all hydrocarbons, melting point decreases with unsaturation. Higher the unsaturation, lower the melting point. For example, oleic acid, linoleic acid and linolenic acid all are unsaturated C18 fatty acids. Oleic acid melts at 13 o C, linoleic acid at -5 o C and linolenic acid at -11 o C.