A single-serving pepperoni pan pizza has 38 g of fat and 780 total calories. (Recall that a food calorie is a kilocalorie.) Estimate the percentage of the total calories from fat.

A serving of two fried chicken thighs has 51 g of fat and furnishes 720 kcal. What percentage of the total calories is from fat?

Exercise 16.1A

A lunch consists of a regular hamburger with 12 g of fat and 275 kcal, a serving of french fried potatoes with 12 g of fat and 240 kcal, and a chocolate milk shake with 9 g of fat and 360 kcal. What percentage of the total calories is from fat?

Exercise 16.1B

EXAMPLE 16.1 Nutrient Calculations

Solution

First, calculate the calories from fat. Fat furnishes about 9 kcal/g, so 38 g of fat furnishes

38 g fat x = 340 kcal9 kcal

1 g fat

Now divide the calories from fat by the total calories. Then multiply by 100% to get the percentage (parts per 100).

% calories from = x 100% = 44%340 kcal

780 kcal

(This answer is only an estimate for two reasons: The value of 9 kcal/g is only approximate and the “38 g of fat” is known only to the nearest gram. A proper answer is “about 44%.”)

EXAMPLE 16.2 Fatty Acids

Solution

a. Fatty acid II has no carbon-to-carbon double bonds; it is a saturated fatty acid.b. Fatty acid III has one carbon-to-carbon double bond; it is a monounsaturated fatty acid.c. Fatty acid I has one of its carbon-to-carbon double bonds three carbons removed from the end

farthest from the carboxyl group (the omega end); it is an omega-3 fatty acid.

Following are line-angle structures of three fatty acids. (a) Which is a saturated fatty acid? (b) Which is a monounsaturated fatty acid? (c) Which is an omega-3 fatty acid?

O

OH

OH

OH

O

O

I.

II.

III.

Which of the fatty acids in Example 16.2 is polyunsaturated?

Exercise 16.2A

Is fatty acid III likely to be more similar physiologically to fatty acid II or to fatty acid I? Explain.

Exercise 16.2B

EXAMPLE 16.2 Fatty Acids continued

Solution

We have seen that ammonium nitrate is made by reacting ammonia with nitric acid. Reacting ammonia with sulfuric acid should therefore give ammonium sulfate. In the form of an equation, we have

NH3 + H2SO4 (NH4)2SO4 (not balanced)

Balancing the equation requires the coefficient 2 for NH3:

2 NH3 + H2SO4 (NH4)2SO4

Write an equation to show the formation of ammonium sulfate (Table 16.8) from ammonia.

Write an equation to show the formation of ammonium monohydrogen phosphate (Table 16.10) from ammonia.

Exercise 16.3A

EXAMPLE 16.3 Fertilizer Production Equations

The micronutrient zinc is often applied in the form of zinc sulfate. Write the equation for the formation of zinc sulfate from zinc oxide.

Exercise 16.3B

What quantity of the pesticide lindane could lead to the death of a 15-kg (33-lb) child if the lethal dose is the same as it is for male rats (Table 16.10)?

How much parathion would it take to kill a 75-kg (165-lb) farm worker if the lethal dose were the same as it is for rats (Table 16.10)?

Exercise 16.4

EXAMPLE 16.4 Pesticide Toxicity

Solution

The lethal dose is given as 88 mg of lindane per kilogram of body weight and the child’s body weight is 15 kg.

The lethal dose is 1300 mg or 1.3 g.

Lethal dose = 15 kg x = 1300 mg88 mg

1 kg

The population of the United States was 300 million in 2005 and was growing at a rate of 0.92% per year. If growth continues at the same rate, when will the population have doubled to 580 million?

How much parathion would it take to kill a 75-kg (165-lb) farm worker if the lethal dose were the same as it is for rats (Table 16.10)?

Exercise 16.5A

EXAMPLE 16.5 Population Growth

Solution

Divide the annual growth rate into 72.

Doubling time = = 78 y72

0.92/y

If growth continues at 0.92% per year, U.S. population will double to 600 million people in 78 years; that is, by 2083. Many factors will affect the growth rate. It will change as the birth rate changes and as immigration laws change. An epidemic or other catastrophe might also change the death rate.

The population of Bulgaria was estimated to be 7.45 million in 2005 and was declining at a rate of 0.89% per year. If the decline continues at this rate, when will the population have been halved to 3.73 million?

Exercise 16.5B