Q: A candy bar contains 225 Cal of nutritional energy. How many joules does it contain? (Use $$1 \text{ Cal} = 4184 \text{ J})$$

$$225 \times 4184 = 941{,}400 \text{ J}$$

Q: Which equation correctly relates heat, mass, specific heat capacity, and temperature change?

$$q = m \times C \times \Delta T$$

Q: Gallium melts at 29.9°C. If 2.5 g of gallium absorbs enough heat to raise its temperature from 25.0°C to 29.9°C, and its specific heat capacity is 0.372 J/g°C, how much heat is absorbed?

$$q = 2.5 \times 0.372 \times (29.9 - 25.0) = 4.57 \text{ J}$$

Q: Convert the normal body temperature, 37°C, into Fahrenheit and Kelvin.

Fahrenheit: $$F = (1.8 \times 37) + 32 = 98.6^\circ \text{F}$$; Kelvin: $$K = 37 + 273 = 310 \text{ K}$$

Q: A 125 g sample of a solid absorbs 1638 J of heat, raising its temperature from 25.0°C to 52.6°C. What is its specific heat capacity?

$$C = \frac{1638}{125 \times (52.6 - 25.0)} = 0.463 \text{ J/g}^\circ \text{C}$$

Question 1

Which of the following best describes the arrangement of water molecules in the solid, liquid, and gas states as shown in the diagram?

Accepted Answer

In solids, molecules are closely packed in a fixed arrangement; in liquids, molecules are close but can move past each other; in gases, molecules are far apart and move freely.

Question 2

A sample of matter has a definite shape and volume, and is not compressible. Which state of matter does this describe?

Accepted Answer

Solid

Question 3

Which property distinguishes a gas from a solid and a liquid, according to the compressibility diagrams?

Accepted Answer

Gases are highly compressible, while solids and liquids are not.

Question 4

Which of the following is a pure substance?

Accepted Answer

Helium gas in a balloon

Question 5

Which method would best separate a mixture of sand and water?

Accepted Answer

Filtration

Question 6

Which of the following is an example of a chemical change?

Accepted Answer

Rusting of iron

Question 7

According to the law of conservation of mass, what happens to the total mass during a chemical reaction?

Accepted Answer

The total mass remains constant.

Question 8

Which of the following statements about energy is correct according to the law of conservation of energy?

Accepted Answer

Energy can be transferred or transformed, but it cannot be created or destroyed.

Question 9

A candy bar contains 225 Cal of nutritional energy. How many joules does it contain? (Use $$1 	ext{ Cal} = 4184 	ext{ J})$$

Accepted Answer

$$225 	imes 4184 = 941{,}400 	ext{ J}$$

Question 10

Which equation correctly relates heat, mass, specific heat capacity, and temperature change?

Accepted Answer

$$q = m 	imes C 	imes \Delta T$$

Question 11

Gallium melts at 29.9°C. If 2.5 g of gallium absorbs enough heat to raise its temperature from 25.0°C to 29.9°C, and its specific heat capacity is 0.372 J/g°C, how much heat is absorbed?

Accepted Answer

$$q = 2.5 	imes 0.372 	imes (29.9 - 25.0) = 4.57 	ext{ J}$$

Question 12

Which of the following is an example of an exothermic reaction?

Accepted Answer

Burning propane in a gas stove

Question 13

What is the specific heat capacity of water in J/g°C?

Accepted Answer

4.184 J/g°C

Question 14

Convert the normal body temperature, 37°C, into Fahrenheit and Kelvin.

Accepted Answer

Fahrenheit: $$F = (1.8 	imes 37) + 32 = 98.6^\circ 	ext{F}$$; Kelvin: $$K = 37 + 273 = 310 	ext{ K}$$

Question 15

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture with uniform composition throughout, such as salt water.

Question 16

Which of the following is a physical property?

Accepted Answer

Boiling point

Question 17

A 125 g sample of a solid absorbs 1638 J of heat, raising its temperature from 25.0°C to 52.6°C. What is its specific heat capacity?

Accepted Answer

$$C = \frac{1638}{125 	imes (52.6 - 25.0)} = 0.463 	ext{ J/g}^\circ 	ext{C}$$

Question 18

Which of the following statements about temperature and heat is correct?

Accepted Answer

Temperature measures the thermal energy of matter, while heat is the transfer of thermal energy due to a temperature difference.

Chapter 3: Matter and Energy – Structured Study Notes

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