Question

the models show the chemical structures of stearic acid (a fatty acid) and stearin (triglyceride). how many molecules of stearic acid are needed to make one molecule of stearin?

Explanation:

Step1: Analyze stearin structure

Stearin is a triglyceride. Triglycerides are formed by the esterification of glycerol (a 3 - carbon alcohol with three - OH groups) and fatty acids.

Step2: Relate to stearic acid

Stearic acid is a fatty acid. In the formation of a triglyceride like stearin, each - OH group of glycerol reacts with a molecule of stearic acid (a fatty acid) to form an ester linkage. Since glycerol has 3 - OH groups, 3 molecules of stearic acid are needed to react with one molecule of glycerol to form one molecule of stearin.

Answer:

3