The names, melting points and structures of two fatty acids are shown below. Bot
ID: 1050723 • Letter: T
Question
The names, melting points and structures of two fatty acids are shown below. Both compounds consist of a carboxylic acid group and a hydrocarbon chain of 18 carbon atoms. Explain the difference in melting point between the two compounds. Saponification of triglycerides gives glycerol and fatty acids salts as shown in the equation below. The groups R_1, R_2 and R_3 represent hydrocarbon chains that may be the same or different. Saponification is actually a hydrolysis reaction. Explain what a hydrolysis reaction is and the role of sodium hydroxide in this process.Explanation / Answer
The geometry of the double bond around the double bond is cis which means that two large griups are on the same side of the double bond. This type of molecule does not stack very well and as a result there is gap between two molecules. Intermolecular attractive forces are also less and so, unsaturated fatty acid like oleic acid has lexx melting point than stearic acid.
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A hydrolysis reaction is breakdown of a bond due to its reaction with water. It can also be viewed breaking of a single bond followed by addition of water (H+ and OH-) in the cleaved parts.
NaOH forms sodium salt with the fatty acid . Sodium salt of fatty acid is known as soap and hence the name saponification.