1. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 1 A Gas 4 Uniformly fills any container. 4 Mixes completely with any other gas 4 Exerts pressure on its surroundings.

2. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 2 Pressure 4 is equal to force/unit area 4 SI units = Newton/meter 2 = 1 Pascal (Pa) 4 1 standard atmosphere = 101,325 Pa 4 1 standard atmosphere = 1 atm = 760 mm Hg = 760 torr

3. Measuring Pressure The first device for measuring atmospheric pressure was developed by Evangelista Torricelli during the 17 th century. The device was called a “barometer” Baro = weight Meter = measure

4. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 4 Figure 5.2 A Torricellian Barometer

5. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 5 Figu re 5.3 A Simple Manometer

6. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 6 Figure 5.4 A J-Tube Similar to the One Used by Boyle

7. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 7 Pressure Conversion Practice

8. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 8 Boyle’s Law *

9. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 9 Boyle’s Law * Pressure  Volume = Constant (T = constant) P 1 V 1 = P 2 V 2 (T = constant) V  1/P (T = constant) ( * Holds precisely only at very low pressures.)

10. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 10 Boyle’s Law *

11. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 11 Figure 5.5 Plotting Boyle’s Data from Table 5.1

12. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 12 A gas that strictly obeys Boyle’s Law is called an ideal gas.

13. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 13 Figure 5.6 A Plot of PV versus P for Several Gases at Pressures Below 1 ATM

14. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 14 Figure 5.7 A Plot of PV Versus P for 1 mol of Ammonia

15. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 15 Charles’s Law

16. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 16 Charles’s Law The volume of a gas is directly proportional to temperature, and extrapolates to zero at zero Kelvin. V = bT (P = constant) b = a proportionality constant

17. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 17 Charles’s Law

18. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 18 Figure 5.8 Plots of V Versus T (ºC) for Several Gases

19. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 19 Figure 5.9 Plots of V Versus T

20. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 20 Charles’s Law

21. Converting Celsius to Kelvin Gas law problems involving temperature require that the temperature be in KELVINS! Kelvins =  C + 273 °C = Kelvins - 273

22. Temperature Conversion Practice

23. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 23 Avogadro’s Law For a gas at constant temperature and pressure, the volume is directly proportional to the number of moles of gas (at low pressures). V = an a = proportionality constant V = volume of the gas n = number of moles of gas

24. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 24 Figure 5.10 Balloons Holding 1.0 L of Gas at 25º C and 1 atm V/n = a Where a is a constant So, what is the value of a at 25°C and 1 atm? (What is its value at STP) V/n is Molar Volume

25. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 25 Figure 5.11 A Mole of Any Gas Occupies a Volume of Approximately 22.4 L at STP

26. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 26 Ideal Gas Law 4 An equation of state for a gas. 4 “state” is the condition of the gas at a given time. PV = nRT

27. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 27 Ideal Gas Law PV = nRT R = proportionality constant = 0.08206 L atm   mol  P = pressure in atm V = volume in liters n = moles T = temperature in Kelvins Holds closely at P < 1 atm

28. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 28 Standard Temperature and Pressure “STP” P = 1 atmosphere T =  C The molar volume of an ideal gas is 22.42 liters at STP

29. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 29 Dalton’s Law of Partial Pressures For a mixture of gases in a container, P Total = P 1 + P 2 + P 3 +...

30. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 30 Figure 5.12 Partial Pressure of Each Gas in a Mixture

31. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 31 Figure 5.13 The Production of Oxygen by Thermal Decomposition of KCIO 3

32. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 32 Ideal Gas Law Manipulation Combined Gas Equation 1 – first state 2 – second state Molar Volume of a Gas Density of a Gas m – mass D – density M – molar mass

33. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 33 Kinetic Molecular Theory 1.Volume of individual particles is  zero. 2.Collisions of particles with container walls cause pressure exerted by gas. 3.Particles exert no forces on each other. 4.Average kinetic energy  Kelvin temperature of a gas.

34. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 34 The Meaning of Temperature Kelvin temperature is an index of the random motions of gas particles (higher T means greater motion.)

35. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 35 Effusion: describes the passage of gas into an evacuated chamber. Diffusion: describes the mixing of gases. The rate of diffusion is the rate of gas mixing.

36. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 36 Effusion: Diffusion:

37. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 37 Real Gases Must correct ideal gas behavior when at high pressure (smaller volume) and low temperature (attractive forces become important).

38. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 38 Real Gases corrected pressure corrected volume P ideal V ideal