Q: If a food label states that a serving contains 150 Calories, how many kilojoules (kJ) does this represent? (1 Cal = 4.184 kJ)

$$150 \times 4.184 = 627.6 kJ$$

Q: A cup of whole milk contains 13 g of carbohydrate, 9.0 g of fat, and 9.0 g of protein. Using the typical energy values (carbohydrate: 4 kcal/g, fat: 9 kcal/g, protein: 4 kcal/g), what is the total energy content in kilocalories (kcal)?

$$(13 \times 4) + (9.0 \times 9) + (9.0 \times 4) = 52 + 81 + 36 = 169$$ kcal

Q: During a calorimetry experiment, a food sample is burned and the temperature of 500 g of water increases by 4.0°C. If the specific heat of water is $$4.184 \ \mathrm{J/g\cdot{}^{\circ}C}$$, what is the total energy released by the food sample in kilojoules (kJ)?

$$q = m \times c \times \Delta T = 500 \times 4.184 \times 4.0 = 8370 J$$ $$= 8.37 kJ$$

Q: A snack contains 7 g of fat, 20 g of carbohydrate, and 2 g of protein. Using the typical energy values (fat: 9 kcal/g, carbohydrate: 4 kcal/g, protein: 4 kcal/g), what is the total energy content in kilojoules (kJ)? (1 kcal = 4.184 kJ)

Total kcal: $$(7 \times 9) + (20 \times 4) + (2 \times 4) = 63 + 80 + 8 = 151$$ kcal; $$151 \times 4.184 = 632 kJ$$

Q: A 70.0-kg adult expends 2100 kJ during an hour of swimming. If this person wants to lose 0.5 kg of body fat (where 1 g of fat = 9 kcal), how many hours of swimming are required? (1 kcal = 4.184 kJ)

0.5 kg = 500 g; $$500 \times 9 = 4500$$ kcal; $$4500 \times 4.184 = 18,828 kJ$$; $$18,828 \div 2100 = 8.97$$ hours

Question 1

A nutritionist uses a calorimeter to determine the energy value of a food sample. Which of the following best describes what is measured in this process?

Accepted Answer

The increase in temperature of the water surrounding the food sample

Question 2

If a food label states that a serving contains 150 Calories, how many kilojoules (kJ) does this represent? (1 Cal = 4.184 kJ)

Accepted Answer

$$150 	imes 4.184 = 627.6 kJ$$

Question 3

Which of the following statements about the nutritional Calorie (with a capital C) is correct?

Accepted Answer

1 Calorie (C) is equal to 1000 calories (c)

Question 4

A cup of whole milk contains 13 g of carbohydrate, 9.0 g of fat, and 9.0 g of protein. Using the typical energy values (carbohydrate: 4 kcal/g, fat: 9 kcal/g, protein: 4 kcal/g), what is the total energy content in kilocalories (kcal)?

Accepted Answer

$$(13 	imes 4) + (9.0 	imes 9) + (9.0 	imes 4) = 52 + 81 + 36 = 169$$ kcal

Question 5

During a calorimetry experiment, a food sample is burned and the temperature of 500 g of water increases by 4.0°C. If the specific heat of water is $$4.184 \ \mathrm{J/g\cdot{}^{\circ}C}$$, what is the total energy released by the food sample in kilojoules (kJ)?

Accepted Answer

$$q = m 	imes c 	imes \Delta T = 500 	imes 4.184 	imes 4.0 = 8370 J$$ $$= 8.37 kJ$$

Question 6

A person burns 2100 kJ of energy during one hour of swimming. How many kilocalories (kcal) is this? (1 kcal = 4.184 kJ)

Accepted Answer

$$2100 \div 4.184 = 502$$ kcal

Question 7

Which of the following best explains why calorimeters are used in nutrition science?

Accepted Answer

They measure the heat released during the combustion of food, which reflects the food's energy content.

Question 8

A nutrition label in Europe lists energy as 840 kJ per serving. What is this value in Calories (kcal)? (1 Cal = 4.184 kJ)

Accepted Answer

$$840 \div 4.184 = 201$$ Cal

Question 9

Which of the following is a correct conversion for energy units used in food labels?

Accepted Answer

1 Cal = 1 kcal = 1000 cal

Question 10

A snack contains 7 g of fat, 20 g of carbohydrate, and 2 g of protein. Using the typical energy values (fat: 9 kcal/g, carbohydrate: 4 kcal/g, protein: 4 kcal/g), what is the total energy content in kilojoules (kJ)? (1 kcal = 4.184 kJ)

Accepted Answer

Total kcal: $$(7 	imes 9) + (20 	imes 4) + (2 	imes 4) = 63 + 80 + 8 = 151$$ kcal; $$151 	imes 4.184 = 632 kJ$$

Question 11

Which of the following best describes the relationship between energy requirements and physical activity?

Accepted Answer

Energy requirements increase with higher levels of physical activity.

Question 12

A 70.0-kg adult expends 2100 kJ during an hour of swimming. If this person wants to lose 0.5 kg of body fat (where 1 g of fat = 9 kcal), how many hours of swimming are required? (1 kcal = 4.184 kJ)

Accepted Answer

0.5 kg = 500 g; $$500 	imes 9 = 4500$$ kcal; $$4500 	imes 4.184 = 18,828 kJ$$; $$18,828 \div 2100 = 8.97$$ hours

Question 13

Which of the following is NOT a correct statement about calorimetry?

Accepted Answer

Calorimetry measures the color change of food during combustion.

Question 14

If a food sample releases 10,000 J of energy in a calorimeter, what is this value in kilocalories (kcal)? (1 kcal = 4184 J)

Accepted Answer

$$10,000 \div 4184 = 2.39$$ kcal

Question 15

A food sample contains 5 g of fat, 10 g of carbohydrate, and 3 g of protein. What is the total energy in Calories (kcal)? (fat: 9 kcal/g, carbohydrate: 4 kcal/g, protein: 4 kcal/g)

Accepted Answer

$$(5 	imes 9) + (10 	imes 4) + (3 	imes 4) = 45 + 40 + 12 = 97$$ kcal

Question 16

Which of the following best explains why energy values for food are different for carbohydrates, fats, and proteins?

Accepted Answer

Each macronutrient releases a different amount of energy per gram when metabolized.

Question 17

A calorimeter contains 250 g of water. After burning a food sample, the temperature of the water increases by 6.0°C. Calculate the energy released in kilojoules (kJ). (Specific heat of water = $$4.184 \ \mathrm{J/g\cdot{}^{\circ}C})$$

Accepted Answer

$$q = 250 	imes 4.184 	imes 6.0 = 6276 J$$ $$= 6.28 kJ$$

Matter and Energy: Calorimetry and Nutrition in GOB Chemistry

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