Question

QUESTION 23 Which of the following fatty acids would you expect to have the lowest melting point? А O= нс OH B H₃C' OH C нус OH D OH CH3 ol. A oll. B o III.C .IV.D Click Save and Submit to save and submit. Click Save All Answers to save all answers.

Answer 1

Answer: IV. D

Explanation:

Saturated fatty acids with highest molecular weight (with high carbon number) having highest melting point. Because with increasing molecular weight van der walls interaction increases which increases attraction between molecules.

Unsaturated fatty acids have lower melting points than saturated fatty acids of the same length. Because double bonds cause the hydrocarbon chain to bend. Therefore, the fatty acids cannot compact tightly together, reducing the van der Waals interaction between the fatty acids.

In unsaturated fatty acids cis form has lower melting point than trans form. Because the "U" shape of the cis isomer doesn't pack as well as the straighter shape of the trans isomer. The poorer packing in the cis isomers means that the intermolecular forces aren't as effective as they should be and so less energy is needed to melt the molecule - a lower melting point.

Among the given molecules A and B are saturated hence have higher melting point. C and D are unsaturated, among C and D, D is cis fatty acid thus it has the lowest melting point.

A. ion Ha Saturated fatty acid with 18 carbon. 8. He -OH Saturated fatty and with 14 Carbon. C. He unsaturated fatty acid with is carbon. Having 4 double bond Trans fatty acid. MA D. OH aid with L cala -unsaturated fatty 18 Carbon Having 4 double bond cis fatty acid.