General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake 2.6 Energy and Nutrition Chapter 2 Energy and Matter © 2013 Pearson Education, Inc. Lectures

© 2013 Pearson Education, Inc. Chapter 2, Section 6 2 Calorimeters A calorimeter  is used to calculate the energy value of food.  contains a reaction chamber and thermometer in water.  indicates the amount of heat lost by food by observing the temperature increase of the water. Heat released from burning a food sample in a calorimeter is used to determine the energy value of the food.

© 2013 Pearson Education, Inc. Chapter 2, Section 6 3 Energy and Nutrition On food labels, energy is shown as the nutritional Calorie, written with a capital C. In countries other than the United States, energy is shown in kilojoules (kJ).

© 2013 Pearson Education, Inc. Chapter 2, Section 6 4 Energy Values for 3 Food Types The energy (caloric) values of food are the kilojoules or kilocalories obtained from burning 1 g of a carbohydrate, fat, or protein.

© 2013 Pearson Education, Inc. Chapter 2, Section 6 5 On packaged foods, the energy content is listed in the Nutrition Facts label on the package, usually in terms of the number of Calories for one serving. Food Nutrition Labels

© 2013 Pearson Education, Inc. Chapter 2, Section 6 6 Energy Content of Some Foods

© 2013 Pearson Education, Inc. Chapter 2, Section 6 7 Calculating Food Energy Values When a 4.0 g sample of fat was combusted in a calorimeter, 164 kJ was absorbed. Calculate the energy value of the fat in kJ/g. Solution: Because 164 kJ was produced by the combustion of 4.0 g of fat, we calculate the energy value with the equation below.

© 2013 Pearson Education, Inc. Chapter 2, Section 6 8 Energy Requirements  The amount of energy needed each day depends on age, gender, and level of physical activity.  If food intake exceeds energy use, a person gains weight.  If food intake is less than energy use, a person loses weight.

© 2013 Pearson Education, Inc. Chapter 2, Section 6 9 A cup of whole milk contains 12 g of carbohydrates, 9.0 g of fat, and 9.0 g of protein. How many kcal (Cal) does a cup of milk contain? (Round to the nearest 10 kcal.) A. 50 kcal (50 Cal) B. 80 kcal (80 Cal) C. 150 kcal (150 Cal) Learning Check

© 2013 Pearson Education, Inc. Chapter 2, Section 6 10 A cup of whole milk contains 12 g of carbohydrates, 9.0 g of fat, and 9.0 g of protein. How many kcal (Cal) does a cup of milk contain? (Round to the nearest 10 kcal.) Solution: Use the mass to kilocalorie conversions to convert grams of each to kilocalories. Answer: C Solution