1. ChemistryS. Martinez Spring 20091

2. KMT based on idea that particles of matter are always in motion.2 3. 1. Gases consist of large numbers of tiny particles that are far apart relative to their size.2. Collisions between gas particles and between particles and container walls are elastic collisions(one in which there is no net loss of KE)3. Gas particles are in continuous, rapid, random motiontherefore possess KE, which is energy of motion. 3 4. 4. There are no forces of attraction or repulsion between gas particles.5. The average KE of gas particles depends on the temp of the gas. [KE = 1/2mv2](the average speeds and KEs of gas particles increase with an increase in temp and decrease with a decrease in tempall gases at the same temp have the same KE but might have different speeds due to their mass)4 5. KMTonly applies to ideal gasesideal gases DO NOT ACTUALLY EXIST but many gases behave nearly ideally if PRESSURE is not very high or TEMPERATURE is not very low. 5 6. Expansion gases do not have a definiteshape/volumecompletely fill a containerin which they are enclosed and take itsshape. Fluidity attractive forces between gasparticles are insignificant, gas particlesslide past one another..this ability allowsthem to behave similarly to liquidsgasesare referred to as fluids. 6 7. Low Density Density of a substance in thegas phase is about 1/1000 the density of thesame substance in the liquid or solidstate.due to gas particles being spreadfarther apart. Compressibility gas particles are able tocrowd close togetherwhen the pressure in acontainer increases the volume of gasparticles may increase by 100 timescompared to the same container that is notpressurized.7 8. 8 9. 9 10. Diffusion& Effusion gases spread out& mix with another without being stirred. Diffusion is the spontaneous mixing of theparticles of 2 substances caused by theirrandom motion. The rate of diffusion depends upon theparticles speeds, diameters, and attractiveforces between them.10 11. Effusion is a process by which gas particles pass through a tiny opening. The rates of effusion of different gases are directly proportional to the velocities of their particles.11 12. All real gases deviate to some degree fromideal-gas behavior. Real gas is a gas that does not behavecompletely according to the assumptionsof the KMT. Real gases occupy space and exertattractive forces on each otherat highpressure and low temps, deviations maybe considerable. 12 13. KMT will hold true for gases whoseparticles have little attraction for eachother. Ex: noble gases and nonpolar gasessuch as Ne, H2, & O2. The more polar a gass molecules are thegreater the attractive forces between themand the more the gas will deviate fromideal gas behavior, ex: NH3 or H2O. 13 14. Pressureis defined as force per unit areaon a surface. Units for pressure: Pascal Mm Hg Torr Atm (atmospheres)STP (standard temp and pressure): 1 atm & 0*CTemp: Kelvins0*C = 273 K14 15. 15 16. 16 17. 17 18. The gas laws are simple mathematical relationships between the volume, temperature, pressure, and amount of gas. 18 19. 1. Boyles Law demonstrates relationship between volume & pressure while temp remains constant. (as one variable increases the other decreases) - states that the volume of a fixed mass of gas varies INVERSELY with the pressure at constant temperature. P1V1 = P2V219 20. Charless Law demonstrates relationshipbetween volume & temperature whilepressure remains constant.- states that the volume of a fixed mass ofgas at a constant pressure variesDIRECTLY with the Kelvin temperature. K = 273.15 + ____ CV1/T1 = V2/T220 21. 3. Gay-Lussacs Law demonstrates relationship between pressure & temperature while volume remains constant. - the pressure of a fixed mass of gas at constant volume varies DIRECTLY with the Kelvin temperature. P1/T1=P2/T221 22. The Combined Gas Law calculatesvolume, temperature, & pressurechanges.- expresses the relationship between thepressure, volume, and temperature of afixed amount of gas.P1V1/T1 = P2V2/T2 22 23. 5. Daltons Law of Partial Pressures - usedto calculate partial pressures and totalpressures.- the pressure of each gas in a mixture iscalled the partial pressure of that gas.- states that the total pressure of a mixtureof gases is equal to the sum of the partialpressures of the component gases.- PT = P1 + P2 + P3 +.23 24. Boyles Law - P1V1 = P2V2 Charless Law - V1/T1 = V2/T2 Gay-Lussacs Law - P1/T1=P2/T2 Combined Gas Law - P1V1/T1 = P2V2/T2 Daltons Law of Partial Pressures - PT = P1+ P2 + P3 +. Conversion from Celsius to Kelvin - K =273.15 + C24 25. A sample of oxygen gas has a volume of 150 mL when its pressure is 0.947 atm. What will the volume of the gas be at a pressure of 0.987 atm if the temperature remains constant?25 26. P1= 0.947 atm V1 = 150 mL P2 = 0.987 atm V2 = X mL (0.947)(150) = 0.987x X = 144 mL of O226 27. Aballoon filled with helium gashas a volume of 500 mL at apressure of 1 atm. The balloon isreleased and reaches an altitudeof 6.5 km, where the pressure is0.5 atm. Assuming that thetemperature has remained thesame, what volume does the gasoccupy at this height?27 28. Answer: 1000 mL He 28 29. A gas has a pressure of 1.26 atm and occupies a volume of 7.40 L. If the gas is compressed to a volume of 2.93 L, what will its pressure be, assuming constant temperature?29 30. Answer: 3.18 atm 30 31. Diversknow that the pressure exerted by the water increases about 100 kPa with every 10.2 m of depth. This means that at 10.2 m below the surface, the pressure is 201 kPa; at 20.4 m, the pressure is 301 kPa; and so forth. Given that the volume of a balloon is 3.5 L at STP and that the temperature of the water remains constant, what is the volume 51 m below the waters surface?31 32. Answer: 0.59 kPa 32 33. Asample of neon gas occupies avolume of 752 mL at 25C. Whatvolume will the gas occupy at50C if the pressure remainsconstant?33 34. V1/T1= V2/T2 or V1T2/T1 V1 = 752 mL T1 = 25C + 273 = 298K V2 = x mL T2 = 50C + 273 = 323K 752/298 = x/323 or (752)(323)/298 X = 815 mL34 35. A helium filled balloon has a volume of 2.75 ml @ 20C. The volume of the balloon decreases to 2.46 ml after it is placed outside on a cold day. What is the outside temperature in K? in C? 35 36. Answer: 262K or -11C36 37. A gas at 65C occupies 4.22L. At what Celsius temperature will the volume be 3.87L, assuming the same pressure? (remember temp must be in Kelvin in the formulaso you will have to convert to Kelvin and then from Kelvin to get the answer) 37 38. Answer: 37C 38 39. The gas in an aerosol can is at a pressure of 3.00 atm at 25C. Directions on the can warn the user not to keep the can in a place where temp exceeds 52C. What would the gas pressure in the can be at 52C? 39 40. P1/T1=P2/T2 or P1T2/T1=P2 P1 = 3.00 atm T1 = 25 + 273 = 298K P2 = x atm T2 = 52 + 273 = 325K 3.00/298 = x/325 or (3.00)(325)/298 X = 3.27 atm40 41. A sample of helium gas has a pressure of 1.20 atm @ 22C. At what celsius temp. will the helium reach a pressure of 2.00 atm?(hint: you have to convert to Kelvin and then from Kelvin)41 42. Answer: 219C or 491.6 K 42 43. A helium filled balloon has a volume of 50.0 L @ 25C and 1.08 atm. What volume will it have at 0.855 atm and 10.C? (convert celcius to kelvins first) 43 44. P1= 1.08 atm V1 = 50.0 L T1 = 25 + 273 = 298K P2 = 0.855 atm V2 = x T2 = 10 + 273 = 283K (1.08)(50.0)/298 = (.855)x/283 X= 60.0 L 44 45. Thevolume of a gas is 27.5ml @ 22C and 0.974 atm.What will the volume be at15C and 0.993 atm?45 46. Answer: 26.3 ml46 47. A700.0 ml gas sample atSTP is compressed to avolume of 200.0 ml, and thetemp is increased to 30.0C.What is the new pressure ofthe gas in Pa? (hint: 1 atm =1.013 25 x 10 5 Pa)47 48. Answer: 3.94 x 105 Pa or 394 kPa 48 49. Helium gas is collected over water @ 25*C. What is the partial pressure of the helium, given that the barometric pressure is 750.0 mm Hg? (hint: use table A-8) 49