$$IS = \frac{56.1 \times N \times V}{m}$$

$$M = \frac{56.1 \times 1000}{IS}$$

Question 1

Which of the following statements correctly describes the relationship between the degree of unsaturation in fatty acids and their melting points?

Accepted Answer

Fatty acids with more double bonds have lower melting points.

Question 2

Given the following structure: $$CH_3$$-($$CH_2)_7-CH=CH$$-($$CH_2)_7-$$COOH$$, identify the fatty acid.

Accepted Answer

Oleic acid

Question 3

Which of the following is the correct formula for calculating the saponification index (IS) of a lipid sample?

Accepted Answer

$$IS = \frac{56.1 	imes N 	imes V}{m}$$

Question 4

A triglyceride is hydrolyzed to yield glycerol and three fatty acids. Which of the following best describes the process?

Accepted Answer

Saponification

Question 5

Which of the following fatty acids is trans-unsaturated?

Accepted Answer

Elaidic acid

Question 6

Calculate the number of moles of iodine that react with 0.1 mol of a fatty acid containing two double bonds per molecule.

Accepted Answer

$$0.2$$ mol

Question 7

Which of the following best explains why polyunsaturated fatty acids have lower melting points than saturated fatty acids?

Accepted Answer

Double bonds introduce kinks, preventing tight packing.

Question 8

A diglyceride is formed from the reaction of glycerol and two fatty acids. What is the general formula for a diglyceride?

Accepted Answer

$$C_3H_5O_4R_2$$

Question 9

Which of the following is a correct statement about the iodine index of a fatty acid?

Accepted Answer

It measures the amount of unsaturated bonds in a fatty acid.

Question 10

Which of the following is the correct formula for calculating the molar mass of a fatty acid from its saponification index?

Accepted Answer

$$M = \frac{56.1 	imes 1000}{IS}$$

Question 11

Which of the following statements about phospholipids is correct?

Accepted Answer

Phospholipids contain a phosphate group and are amphipathic.

Question 12

Which of the following is a correct statement about the structure of a monounsaturated fatty acid?

Accepted Answer

It contains one double bond between carbon atoms.

Question 13

Which of the following is the correct order of melting points for the following fatty acids: stearic acid, oleic acid, linoleic acid?

Accepted Answer

Stearic acid \u003e Oleic acid \u003e Linoleic acid

Question 14

Which of the following is the correct formula for a saturated fatty acid with 18 carbon atoms?

Accepted Answer

$$C_{18}H$$_{36}$$O_2$$

Question 15

Which of the following best describes the role of glycerol in triglycerides?

Accepted Answer

Glycerol acts as a backbone to which three fatty acids are esterified.

Question 16

Which of the following is a correct statement about the difference between cis and trans fatty acids?

Accepted Answer

Trans fatty acids have hydrogen atoms on opposite sides of the double bond.

Question 17

Which of the following is the correct formula for a diglyceride formed from glycerol and two palmitic acid molecules?

Accepted Answer

$$C_{35}H$$_{68}$$O_4$$

Question 18

Which of the following is a correct statement about the saponification reaction?

Accepted Answer

It produces fatty acids and glycerol from triglycerides.

Question 19

Which of the following is the correct formula for the calculation of the number of double bonds in a fatty acid using the iodine index?

Accepted Answer

$$n = \frac{I}{254}$$

Les Lipides : Structure, Classification et Propriétés

Study Guide - Practice Questions