Q: Which of the following statements best describes the relationship between calories and joules?

$$1 \ \text{cal} = 4.184 \ \text{J}$$

Q: A 70.0 Cal serving of bread contains how many joules of energy? (Note: 1 Cal = 1000 cal, $$1 \ \text{cal} = 4.184 \ \text{J})$$

$$2.93 \times 10^5$ \ \text{J}$$

Q: If 150.0 g of iron ($$c = 0.108 \ \text{cal/g}^\circ\text{C}) is $$heated from $$25.0^\circ\text{C} to$$ $$73.3^\circ\text{C}$$, how much heat is absorbed?

$$q = 150.0 \times 0.108 \times (73.3 - 25.0) = 783 \ \text{cal}$$

Q: Which of the following substances would require the most energy to raise the temperature of 10.0 g by $$1^\circ\text{C}$$?

Hydrogen ($$c = 3.419 \ \text{cal/g}^\circ\text{C})$$

Q: A person walks upstairs for 30 minutes. If the energy expenditure is $$1,200 \ \text{kcal/h}$$, how many kilojoules (kJ) did they use? ($$1 \ \text{kcal} = 4.184 \ \text{kJ})$$

$$1,200 \times 0.5 \times 4.184 = 2,510 \ \text{kJ}$$

Q: If you want to heat 50.0 g of water from $$20.0^\circ\text{C} to$$ $$80.0^\circ\text{C}$$, how much heat (in calories) is required? ($$c = 1.00 \ \text{cal/g}^\circ\text{C})$$

$$q = 50.0 \times 1.00 \times (80.0 - 20.0) = 3,000 \ \text{cal}$$

Q: A 100.0 g sample of copper ($$c = 0.092 \ \text{cal/g}^\circ\text{C}) is $$heated by $$30.0^\circ\text{C}. $$How much heat is absorbed?

$$q = 100.0 \times 0.092 \times 30.0 = 276 \ \text{cal}$$

Question 1

Which of the following statements best describes the relationship between calories and joules?

Accepted Answer

$$1 \ 	ext{cal} = 4.184 \ 	ext{J}$$

Question 2

A 70.0 Cal serving of bread contains how many joules of energy? (Note: 1 Cal = 1000 cal, $$1 \ 	ext{cal} = 4.184 \ 	ext{J})$$

Accepted Answer

$$2.93 	imes 10^5$ \ 	ext{J}$$

Question 3

Which of the following best explains why you feel cold when holding an ice cube?

Accepted Answer

Heat flows from your hand into the ice cube due to the temperature difference.

Question 4

What is the correct formula to calculate the quantity of heat ($$q) $$transferred to or from a substance?

Accepted Answer

$$q = mc \Delta T$$

Question 5

If 150.0 g of iron ($$c = 0.108 \ 	ext{cal/g}^\circ	ext{C}) is $$heated from $$25.0^\circ	ext{C} to$$ $$73.3^\circ	ext{C}$$, how much heat is absorbed?

Accepted Answer

$$q = 150.0 	imes 0.108 	imes (73.3 - 25.0) = 783 \ 	ext{cal}$$

Question 6

Which of the following substances would require the most energy to raise the temperature of 10.0 g by $$1^\circ	ext{C}$$?

Accepted Answer

Hydrogen ($$c = 3.419 \ 	ext{cal/g}^\circ	ext{C})$$

Question 7

A person walks upstairs for 30 minutes. If the energy expenditure is $$1,200 \ 	ext{kcal/h}$$, how many kilojoules (kJ) did they use? ($$1 \ 	ext{kcal} = 4.184 \ 	ext{kJ})$$

Accepted Answer

$$1,200 	imes 0.5 	imes 4.184 = 2,510 \ 	ext{kJ}$$

Question 8

Which of the following best describes specific heat?

Accepted Answer

The amount of energy required to raise the temperature of 1 g of a substance by $$1^\circ	ext{C}.$$

Question 9

Which exercise from the provided table expends the least energy per hour?

Accepted Answer

Golfing, with cart

Question 10

If you want to heat 50.0 g of water from $$20.0^\circ	ext{C} to$$ $$80.0^\circ	ext{C}$$, how much heat (in calories) is required? ($$c = 1.00 \ 	ext{cal/g}^\circ	ext{C})$$

Accepted Answer

$$q = 50.0 	imes 1.00 	imes (80.0 - 20.0) = 3,000 \ 	ext{cal}$$

Question 11

Which of the following is NOT a correct unit for specific heat?

Accepted Answer

$$	ext{g/cal}^\circ	ext{C}$$

Question 12

A 100.0 g sample of copper ($$c = 0.092 \ 	ext{cal/g}^\circ	ext{C}) is $$heated by $$30.0^\circ	ext{C}. $$How much heat is absorbed?

Accepted Answer

$$q = 100.0 	imes 0.092 	imes 30.0 = 276 \ 	ext{cal}$$

Question 13

Which of the following best describes the cause of heat transfer between two objects?

Accepted Answer

A difference in temperature between the objects.

Question 14

If you burn 500 kcal during a soccer game, how many kilojoules (kJ) is this? ($$1 \ 	ext{kcal} = 4.184 \ 	ext{kJ})$$

Accepted Answer

$$500 	imes 4.184 = 2,092 \ 	ext{kJ}$$

Question 15

Which of the following would require the least amount of heat to raise the temperature of 20.0 g by $$10^\circ	ext{C}$$?

Accepted Answer

Mercury ($$c = 0.033 \ 	ext{cal/g}^\circ	ext{C})$$

Question 16

A 200.0 g sample of aluminum ($$c = 0.215 \ 	ext{cal/g}^\circ	ext{C}) is $$cooled from $$100.0^\circ	ext{C} to$$ $$25.0^\circ	ext{C}. $$What is the value and sign of $$q$$?

Accepted Answer

$$q = 200.0 	imes 0.215 	imes (25.0 - 100.0) = -3,225 \ 	ext{cal}$$

Energy and Chemical Processes: Study Notes for General Chemistry

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