23. Lipids

Which of these fatty acids has the lower melting point? Explain why.

a. Linoleic acid

b. Stearic acid

Can there be any chiral carbon atoms in triacylglycerols? If so, which ones can be chiral and what determines their chirality?

Which of these fatty acids has the higher melting point? Explain why.

a. Linolenic acid

b. Stearic acid

Safflower oil is polyunsaturated, whereas olive oil is monounsaturated. Why would safflower oil have a lower melting point than olive oil?

Lipids are not soluble in water. Are lipids polar or nonpolar molecules?

Which of the following solvents might be used to dissolve an oil stain?

a. water

b. CCl₄

c. diethyl ether

d. benzene

e. NaCl solution

How does the percentage of monounsaturated and polyunsaturated fatty acids in olive oil compare to that of canola oil?

The total kilocalories and grams of fat for some typical meals at fast-food restaurants are listed here. Calculate the number of kilocalories and the percentage of total kilocalories from fat (1 gram of fat = 9 kcal). Round answers to the tens place.

a. a beef burrito, 470 kcal, 21 g of fat

Considering their chemical structure, why are the melting points of oils lower than those of fats?

Olive oil is a monounsaturated oil with a melting point of -6 °C. Soybean oil is a polyunsaturated oil with a melting point of -16 °C . Explain their difference in melting points.

Stearic acid and linoleic acid each have 18 carbon atoms. Why does stearic acid melt at 69 °C but linoleic acid melts at –5 °C?

The total kilocalories and grams of fat for some typical meals at fast-food restaurants are listed here. Calculate the number of kilocalories and the percentage of total kilocalories from fat (1 gram of fat = 9 kcal). Round kcals to the tens place.

a. a beef burrito, 470 kcal, 21 g of fat