Chapter 3: States of Matter

1. Chapter 3:States of Matter Section 4:Behaviors of Gases

2. Bellringer The pressure of gas depends on how frequently the particles of gas strike the sides of the container holding the gas. Use your experience and, after examining each of the pairs of drawings shown below, decide whether you think the pressure of the contained gas has increased, decreased, or remained unchanged. Choose the correct answer. 1. The gas in the cylinder of an automatic engine undergoes the change shown below. Does the pressure of the gas a. increase? b. decrease? c. remain unchanged?

3. Bellringer, continued 2. The gas in the toy balloon expands outward, as shown below. After this expansion, does the pressure of the gas a. increase? b. decrease? c. remain unchanged? 3. The temperature of the water vapor in the pressure cooker increases. Does the pressure of the gas a. increase? b. decrease? c. remain unchanged?

4. Properties of Gases • Here are some properties of gases: • Gases expand to fill their containers. • They spread out easily and mix with one another. • They have low densities and are compressible. • Unlike solids and liquids, gases are mostly empty space. • Gases exert pressure on their containers.

5. Properties of Gases

6. Gas Laws • Boyle’s law relates the pressure of a gas to its volume. • Boyle’s law: For a fixed amount of gas at a constant temperature, the volume of a gas increases as the gas’s pressure decreases. Likewise, the volume of a gas decreases as the gas’s pressure increases. • P1V1 = P2V2

7. Visual Concept: Boyle’s Law

8. Math Skills Boyle’s Law The gas in a balloon has a volume of 7.5 L at 100 kPa. The balloon is released into the atmosphere, and the gas expands to a volume of 11 L. Assuming a constant temperature, what is the pressure on the balloon at the new volume? Remember, our formula reads: P1V1 = P2V2 1. List the given and unknown values. Given:V1 = 7.5 LP1 = 100 kPaV2 = 11 L Unknown: P2

9. Math Skills, continued 2. Write the equation for Boyle’s law, and rearrange the equation to solve for P2. 3. Insert the known values into the equation, and solve. P1V1 = P2V2 • P2 = 68 kPa

10. Gas Laws, continued • Gay-Lussac’s law relates gas pressure to temperature. • Gay-Lussac’s law: The pressure of a gas increases as the temperature increases, if the volume of the gas does not change. The pressure decreases as the temperature decreases. • Charles’s law relates temperature to volume. • Charles’s law: For a fixed amount of gas at a constant pressure, the volume of the gas increases as the gas’s temperature increases. Likewise, the volume of the gas decreases as the gas’s temperature decreases.

11. The volume of a gas increases as the gas’s pressure decreases. Likewise, the volume of a gas decreases as the gas’s pressure increases. • Gay-Lusaac’s Law • Charles’ Law • Boyle’s Law

12. The volume of a gas increases as the gas’s temperature increases. Likewise, the volume of a gas decreases as the gas’s temperature decreases. • Gay-Lusaac’s Law • Charles’ Law • Boyle’s Law

13. The pressure of a gas increases as the gas’s temperature increases. Likewise, the pressure of a gas decreases as the gas’s temperature decreases. • Gay-Lusaac’s Law • Charles’ Law • Boyle’s Law

14. Visual Concept: Charles’s Law

15. FOR HOMEWORK Page 101 1-5, 10

16. Boyle’s law relates the pressure of a gas to its Temperature Volume Container composition

17. Charles’s law relates the volume of a gas to its Container Pressure Composition temperature

18. The gas law relating the temperature and pressure of a gas is Gay-Lussac’s law Boyle’s law Archimedes’ Principle Charles’s law

19. As the temperature of a gas at a constant volume decreases, its pressure Decreases Stays the same Increases disappears

20. Gases are unique in comparison to solids and liquids because they Obey Bernoulli’s principle Have no definite shape Are fluids Are easily compressible

21. As the pressure of a gas at a constant temperature decreases, its volume Decreases Stays the same Increases None of the above

22. Which law is illustrated by the equation P1V1=P2V2? Charles’s Law Boyle’s Law Gay-Lussac’s Law Archimedes’ Principle

23. Which of these properties is shared by solids, liquids, and gases? They expand to fill their containers. Their particles are in constant motion. They are easily compressible. They are fluids.

24. Why does the volume of a gas decrease when the pressure increases? Gas particles slow down when pressure is increased. Gas particles bond when the pressure is increased. Gas particles are pushed together when the pressure is increased. Gas particles become smaller when the pressure is increased.