1. Introduction to Gases Earth is surrounded by a layer of gaseous molecules - the atmosphere - extending out to about 50 km.

2. Characteristics of Gases Gases  low density; compressible  volume and shape of container  expand when heated  large distance between particles Model of a gas:  rapidly moving particles: vol. & shape of container  no attraction between particles  moving about freely  large space between particles: low density & high compressibility 12m05vd1

3. Liquids and Solids Liquids  higher density, lower compressibility  characteristic volume; shape of container  particles closer together; moving about; experience attractive forces Solids  high density; low compressibility  particles are close together; little empty space; strong attractive forces  characteristic volume and shape

4. Atomic View of the States of Matter Note distance between particles and order of arrangement of particles Figure 9.1 01m07an1

5. States of Matter

6. Pressure Pressure = force/area Units: lb/ft 2 Pa = N/m 2 = kg/ms 2 torr = mm Hg atm 1 atm = 760 torr= 760 mm Hg 1 atm = 29.9 in Hg = 14.7 lb/in 2 1 atm = 101.3 kPa Measure pressure with barometer or U- tube or manometer

7. Barometer What is in a vacuum? What is the weight of the atmosphere? Figure 9.3

8. Pressure Lab: soft drink can

9. Charles’ Law- Relationship between: _________ and __________ Variables/Units Held Constant Relationship (direct or inverse) In words T = K V = L P = atm n = moles Direct As temperature goes up, volume goes up

10. Charles’ Law Graph of Relationship

11. Charles’ Law As x increases, y stays the same, no relationship. y = b y is constant As x increases, y increases Y = mx + b As x increases, y decreases Y = m(1/x) + b

12. Charles’ Law Charles’ Law Formula How to convert C to K F to C to K V = m(T) + bb = 0 V/T = m m= constant V 1 /T 1 = V 2 /T 2 K = C + 273 C = 5/9(F-32) K = C + 273

13. Charles’ Law Temperature Conversion Practice Practice Problem Convert 212 degrees F to K Convert 50degrees C to K The volume of a sample of gas is 2.50L at 45K. What is the volume when it is heated to 125K at a constant pressure.

14. Brainteaser A sample of nitrogen occupies a volume of 250 mL at 25 ºC. What volume will it occupy at 95ºC. Fluorine gas at 300 K occupies a volume of 500 mL. To what temperature should it be lowered to bring the volume to 300 mL?

15. Pressure Why does a pin hurt? Why don’t snowshoes sink?

16. Charles Law classwork Worksheet

17. Boyle’s Law: The relationship between _______ & ________ Variables/Units Held Constant Volume (L) Pressure (atm) Temperature (K) Moles (n)

18. Boyle’s Law: Relationship (direct or inverse) Relationship in words Inverse As pressure increases volume decrease.

19. Boyle’s Law Sketch Graph Pressure vs. Volume

20. Boyle’s Law Sketch Graph Pressure vs. 1/ V

21. Boyle’s Law Formula Pressure Units P = m (1/V) + b b= 0 PV = m m = constant P 1 V 1 = P 2 V 2 atm = atmospheres mmHg = millimeters of mercury torr Pa = Pascals psi = pounds per square inch 1 atm = 101,325Pa = 760 mmHg = 760 torr = 14.70psi

22. Boyle’s Law Formula Pressure Unit Conversions 1 atm = 101,325Pa = 760 mmHg = 760 torr = 14.70psi

23. Boyle’s Law How to convert from pressure units to atm (use dimensional analysis) Convert 458mmHg to atm Convert 96.5 lb/in 2 to atm Convert 485kPa to atm

24. Boyle’s Law Boyle’s Law Practice Problem The pressure on 2.5L of anesthetic gas is changed from 760mmHg to 304mmHg. What will be the new volume of the gas?

25. review Boyle’s Law Sulfur dioxide, a gas that plays a central role in the formation of acid rain, is found in the exhaust of automobiles and power plants. Consider a 1.53 L sample of gaseous sulfur dioxide at a pressure of 5.6 x 10 3 Pa. If the pressure changed to 0.148 atm at a constant temperature, what will be the new volume of gas?

26. Boyles Law Classwork Boyles law worksheet

27. Unit Conversion Convert to the following units P = atm V = Liters T = Kelvin

28. Combined Gas Law Boyle’s Law Charles’s Combined

29. Avogadro’s Law How can we change the volume of a gas in a balloon? Liquid N2 balloon

30. Avogadro’s Law Why did the blimp deflate?

31. Avogadro’s Law If the pressure and temperature are held constant, the volume of a gas is directly proportional to the number of moles (n). V n

32. Avogadro’s Law Suppose we have a 12.2 L sample containing 0.50 mol oxygen gas at a pressure of 1 atm and a temperature of 25 º C. If all this oxygen is converted to ozone at the same temperature and pressure, what would be the volume of the ozone?

33. The Gas Laws Variables: V, P, T, n (or m and MM or d) Ideal Gas: properties are independent of the identity of the gas What is the relationship between the variables for an ideal gas? BasketballBike Tire

34. 5.3 Ideal Gas Law PV = nRT P= pressure V = volume n = number of moles R = ideal gas constant  0.08206 L·atm/mol·K T = temperature

35. STP Standard Temperature and Pressure  0 º C and 1 atm Use the Ideal Gas Law to calculate the volume of 1.00 mol of gas at STP

36. Molar Volume at STP We can show that 22.414 L of any gas at 0  C and 1 atm contain 6.02  10 23 gas molecules.

37. Example A sample of Hydrogen gas has a volume of 8.56 L at 0 ºC and a pressure of 1.5 atm. Calculate the moles H 2 molecules present in this gas sample.

38. Practice Problem The volume of an oxygen cylinder is 1.85 L. What mass of oxygen gas remains in the cylinder when it is “empty” if the pressure is 755 torr and the temperature is 18.1 o C? Answer: 2.46 g

39. Gas Law Stoichiometry Quicklime (CaO) is produced by the thermal decomposition of calcium carbonate. Calculate the volume of CO 2 at STP produced from the decomposition of 152 g of CaCO 3 by the reaction CaCO 3 (s)  CaO (s) + CO 2 (g)

40. Molar Mass and the Ideal Gas Law If 0.126 g of a gas are contained in a 25mL tank at 25 ºC and 3.25 atm, what is the molar mass of the gas? What is the gas?

41. Kinetic Molecular Theory A model that attempts to explain the behavior of an ideal gas. The particles are so small that compared with the distances between them that the volume of the individual particles can be assumed to be negligible (zero). The particles are in constant motion. The collisions of the particles with the walls of the container are the cause of the pressure exerted by the gas.

42. Kinetic Molecular Theory The particles are assumed to exert no forces on each other; they are assumed to neither attract nor repel each other. The average kinetic energy of a collection of gas particles is assumed to be directly proportional to the Kelvin temperature of the gas.

43. When does the Kinetic Molecular Theory break down? What conditions would cause our assumptions to become in valid?

44. Derivations from the Ideal gas law: Derivations occur in non-ideal conditions such as low temperature or high pressure: At high density the volume of the particles themselves become important. Gas particles do attract each other when they are close together.