Multiple Choice
Arrange the following fatty acids in order of decreasing solubility in a hexane solution.
I. Myristic Acid II. Stearic Acid III. Lauric Acid IV. Arachidic Acid
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32. Lipids
Physical Properties of Fatty Acids
Multiple Choice
The fatty acid percentage composition from various commercially available oils is given below. Based on what you know about fatty acids, determine which of the following would have the highest melting point?
A
Source A
B
Source B
C
Source C
D
Source D
Verified step by step guidance1
Identify the types of fatty acids present in each source. Saturated fatty acids include Palmitic, Stearic, and Arachidic acids, while unsaturated fatty acids include Palmitoleic, Oleic, and Arachidonic acids.
Recall that saturated fatty acids generally have higher melting points than unsaturated fatty acids due to their ability to pack closely together, resulting in stronger van der Waals forces.
Examine the table to determine the percentage composition of saturated fatty acids in each source. Source C has the highest percentage of saturated fatty acids (44% Palmitic, 22% Stearic, and 21% Arachidic).
Consider the impact of unsaturated fatty acids on melting point. Unsaturated fatty acids, especially those with multiple double bonds like Arachidonic acid, tend to lower the melting point due to kinks in their structure that prevent tight packing.
Conclude that Source C, with the highest percentage of saturated fatty acids and no unsaturated fatty acids, would have the highest melting point among the given sources.
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