1. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 1 Chemistry FIFTH EDITION by Steven S. Zumdahl University of Illinois

2. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 2 Chemistry FIFTH EDITION Chapter 5 Gases

3. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 3 Section 5.4 Gas Stoichiometry What is the volume of a mole of gas at exactly 0  C and 1 atm.? P V = n R T V = (n R T)/ P V = (1 mole)(0.08206 Latm/mole K)(273.15 K) (1 atm) V = 22.42 L

4. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 4 Standard Temperature and Pressure “STP” P = 1 atmosphere T =  C The molar volume of an ideal gas is 22.42 liters at STP

5. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 5 Figure 5.11 A Mole of Any Gas Occupies a Volume of Approximately 22.42 L at STP

6. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 6 Practice Exercises Let’s do Exercises 48.

7. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 7 Molar Mass of a Gas n = # of moles = grams of gas= (m) molar mass molar mass

8. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 8 P V = n R T P V = (m/molar mass) R T Therefore, molar mass = m R T P V

9. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 9 Also, since density (d) = m V Then, molar mass = d R T P Let’s do Exercise 58!!

10. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 10 Homework WebAssign

11. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 11 Section 5.5 Dalton’s Law of Partial Pressures For a mixture of gases in a container, the Total Pressure exerted is the sum of the pressures that each gas would exert if it were alone. P Total = P 1 + P 2 + P 3 +... Each gas assumed to be ideal.

12. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 12 Figure 5.12 Partial Pressure of Each Gas in a Mixture

13. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 13 Since P 1 = n 1 RT/ V and P 2 = n 2 RT/V etc. Then, P T = n 1 RT + n 2 RT + … V V Or, P T = (n 1 + n 2 + …) RT = n total RT V V

14. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 14 For an Ideal Gas Pressure depends only on the total number of moles of particles. Not the identity. Not the Composition.

15. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 15 Therefore, For an Ideal Gas The Volume of the individual gas particle must not be important. the forces among the particles must not be important. Let’s do Exercises 61 & 62

16. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 16 Mole Fraction # of moles of a given component in a mixture Total # of moles in a mixture χ 1 = n 1 = n 1 n total n 1 + n 2 + …

17. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 17 Since n 1 = P 1 Vetc. RT Then, χ 1 = P 1 (V/RT) ( P 1 + P 2 + …) (V/RT) = P 1 / P total

18. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 18 Thus, χ 1 = P 1 = n 1 P total n total Or, P 1 = χ 1 P total Partial pressure of a particular component is the mole fraction of that component times the total pressure.

19. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 19 Let’s do #66

20. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 20 Gases in Reactions are often collected By displacement of Water.

21. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 21 Consider the decomposition of potassium chlorate 2 KClO 3 (s)  2 KCl (s) + 3 O 2 (g) Oxygen gas is produced and collected in the bottle as a mixture of O 2 and water vapor.

22. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 22 Figure 5.13 The Production of Oxygen by Thermal Decomposition of KClO 3

23. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 23 2 KClO 3 (s)  2 KCl (s) + 3 O 2 (g) P total = P (O 2 ) + P (H 2 O) vapor pressure of water

24. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 24 Exercises!!! Let’s do #68 & 70!! Homework: WebAssign 5.4 & 5.5