1. Section 13.1 Describing the Properties of Gases Chapter Preview: 1.How does a gas differ from a solid and a liquid 2.Have you heard of the term barometric pressure? What does it mean? 3.What does the temperature of a sample measure?

2. Section 13.1 Describing the Properties of Gases 1.To learn about atmospheric pressure and how barometers work 2.To learn the units of pressure 3.To understand how the pressure and volume of a gas are related 4.To do calculations involving Boyle’s Law 5.To learn about absolute zero 6.To understand how the volume and temperature of a gas are related 7.To do calculations involving Charles’s Law 8.To understand how the volume and number of moles of a gas are related 9.To do calculations involving Avogadro’s Law Objectives

3. Section 13.1 Describing the Properties of Gases A. Pressure –Changing weather conditions Atmospheric Pressure

4. Section 13.1 Describing the Properties of Gases A. Pressure –Changing altitude Atmospheric Pressure

5. Section 13.1 Describing the Properties of Gases A. Pressure Barometer – device that measures atmospheric pressure –Invented by Evangelista Torricelli in 1643 Measuring Pressure

6. Section 13.1 Describing the Properties of Gases A. Pressure Barometer

7. Section 13.1 Describing the Properties of Gases A. Pressure 1 standard atmosphere = 1.000 atm = 760.0 mm Hg = 760.0 torr = 101,325 Pa = 14.70 psi (lb/in 2 ) = 29.9 in. Hg = 1013 mbar Units of Pressure

8. Section 13.1 Describing the Properties of Gases Converting Pressure Units On a summer day in Breckenridge, Colorado, the atmospheric pressure is 525 mm Hg. What is the air pressure in atmospheres (atm)? mm Hg and atm are related by the unit equality: 1.000 atm = 760.0 mm Hg Therefore: (525 mm Hg)(1.000 atm/760.0 mm Hg) = 0.691 atm

9. Section 13.1 Describing the Properties of Gases Practice Problems 1.The height of mercury in a mercury barometer is measured to be 732 mm Hg. Calculate this pressure in atm. 2.The pressure of a gas is measured to be 2.79 x 10 5 Pa. Represent this pressure in mm Hg. 3. The air pressure in a submarine is 0.62 atm. What is the pressure in psi?

10. Section 13.1 Describing the Properties of Gases A. Pressure Units of Pressure A manometer measures the pressure of a gas in a container.

11. Section 13.1 Describing the Properties of Gases Measuring Pressure 1.A balloon is attached to an open-ended manometer. The difference in height of the mercury column is 13 mm. The side attached to the balloon is lower than the side open to the atmosphere. If the pressure of the atmosphere is known to be 755 mm Hg, what is the gas pressure in the balloon? 2. A gas container is attached to a manometer. The level of the mercury is 15 mm lower on the open side. If the atmospheric pressure is 750 mm Hg, what is the pressure of the gas in the container?

12. Section 13.1 Describing the Properties of Gases B.Pressure and Volume Class Warmup Describe what will happen to a sample of gas in a container if the container volume is doubled but the temperature and amount of gas stays the same.

13. Section 13.1 Describing the Properties of Gases 1662 – Robert Boyle discovered the relationship between pressure and volume The volume of a fixed amount of gas is inversely proportional to the pressure at constant temperature. B. Pressure and Volume: Boyle’s Law

14. Section 13.1 Describing the Properties of Gases B. Pressure and Volume: Boyle’s Law As volume decreases, particles collide more often so the pressure increases. If volume increases, particles collide less frequently and pressure decreases.

15. Section 13.1 Describing the Properties of Gases

16. Section 13.1 Describing the Properties of Gases PV = k Or P 1 V 1 =P 2 V 2 B. Pressure and Volume: Boyle’s Law

17. Section 13.1 Describing the Properties of Gases C. Volume and Temperature: Charles Law Class Warmup: Describe what will happen to a sample of a gas in a container that is free to expand or contract if the temperature of the gas is increased.

18. Section 13.1 Describing the Properties of Gases C. Volume and Temperature: Charles Law The relationship between volume and temperature of a gas was discovered by Jacques Charles in 1787. The volume of a fixed mass of gas at constant pressure is directly proportional to the Kelvin temperature.

19. Section 13.1 Describing the Properties of Gases C. Volume and Temperature: Charles’s Law Or….

20. Section 13.1 Describing the Properties of Gases Absolute zero – temperature at which a gas volume becomes zero (all particle motions stops -273 o C  0 Kelvin (K) C. Volume and Temperature: Charles’s Law

21. Section 13.1 Describing the Properties of Gases D. Volume and Moles: Avogadro’s Law What happens when gas particles are added to a container that that is free to expand or contract. Assume the temperature is constant?

22. Section 13.1 Describing the Properties of Gases D. Volume and Moles: Avogadro’s Law

23. Section 13.1 Describing the Properties of Gases D. Volume and Moles: Avogadro’s Law Volume and moles are directly proportional at constant temperature and pressure –If one increases the other increases.

24. Section 13.1 Describing the Properties of Gases D. Volume and Moles: Avogadro’s Law Discovered in 1811 by Amadeo Avodgadro Equal volumes of a gas at constant temperature and pressure contain equal number of particles.

25. Section 13.1 Describing the Properties of Gases D. Volume and Moles: Avogadro’s Law Practice Problems: 1.If 2.55 moles of helium gas occupies a volume of 59.5 L at a particular temperature and pressure, what volume does 7.83 moles of helium occupy under the same conditions? 2. If 4.35 g of neon gas occupies a volume of 15.0 L at a particular temperature and pressure, what volume does 2.00 g of neon gas occupy under the same conditions?

26. Section 13.1 Describing the Properties of Gases E.Pressure and Temperature: Gay-Lussac’s Law Describe what happens to a sample of gas in a rigid sealed container if the gas is heated.

27. Section 13.1 Describing the Properties of Gases E. Pressure and Temperature: Gay-Lussac’s Law Pressure and Temperature are directly proportional -P and T are related by the equation: P/T = k (constant) - at constant volume and constant amount of gas Another way of stating Gay-Lussac’s Law is: P 1 = P 2 T 1 T 2