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Chapter 2 Energy and Matter

2.2 Energy and

Nutrition

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Calorimeters

A calorimeter

• is used to measure heat transfer.

• can be made with a coffee cup and a thermometer.

• indicates the heat lost by a sample

• indicates the heat gained by water.

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Energy and Nutrition

On food labels, energy is shown as the nutritionalCalorie, written with a capital C. In countries other than the U.S., energy is shown in kilojoules (kJ).

1 Cal = 1000 calories1 Cal = 1 kcal1 Cal = 1000 cal1 Cal = 4184 J

1 Cal = 4.184 kJ

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Caloric Food Values

The caloric or energy values for foods indicate thenumber of kcal(Cal) provided by 1 g of each type of food.

Carbohydrate: 4 kcal 1 g

Fat (lipid): 9 kcal 1 g

Protein: 4 kcal 1 g

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Energy Values for Some Foods

TABLE 2.2

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Energy Requirements

• The amount of energy needed each day depends on age, sex, and physical activity.

TABLE 2.3

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A cup of whole milk contains 12 g of carbohydrate, 9.0 g of fat, and 5.0 g of protein. How many kcal (Cal) does a cup of milk contain?

1) 48 kcal (or Cal)2) 81 kcal (or Cal)3) 150 kcal (or Cal)

Learning Check

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A cup of whole milk contains 12 g of carbohydrate, 9.0 g of fat, and 5.0 g of protein. How many kcal (Cal) does a cup of milk contain?

3) 150 kcal (or Cal)

12 g carbohydrates x 4 kcal/g = 50 kcal (1 SF) 9.0 g fat x 9 kcal/g = 80 kcal (1 SF)5.0 g protein x 4 kcal/g = 20 kcal (1 SF)

150 kcal

Solution