Chapter 5§5.2 Pressure5.2 Barometer§5.3 The Simple Gas Laws§5.3 Boyle’s LawSlide 6Slide 7§5.3 Boyle’s Law and Ideal Gases§5.3 Diving§5.3 Charles’ LawCharles’ LawSlide 12Liquid Nitrogen (LN2)Liquid Nitrogen (LN2)§5.3 Avogadro’s Law§5.3 Avogadro’s Law§5.4 Ideal Gas LawSlide 18Slide 19§5.5 STP and Molar VolumeSlide 21The moveable piston-cylinder below contained which gaseous reaction at constant P?§5.5 Calculations at STP§5.5 Molar Mass of a Gas§5.5 Molecular Formula of a GasThe density of a gaseous compound is 0.915 g/L at 1.30 atm and 300. K. What is the compound? R = 0.08206§5.6 Partial PressuresSlide 28PowerPoint Presentation§5.6 Collecting a Gas over WaterSlide 31Slide 32Kinetic Molecular Theory (KMT)§5.8 Kinetic Energy§5.8 Temperature and Kinetic Energy§5.8 Root Mean Square Velocity (urms)§5.8 Derivation of Root Mean Square Velocity (urms)Slide 38Slide 39§5.9 Effusion vs Diffusion§5.9 Graham’s Law of EffusionSlide 42§5.10 Real vs Ideal Gases§5.10 van der Waals EquationSlide 45§5.10 van der Waals vs PV = nRT§5.10 Real vs. Ideal GasesGASESChapter 5§5.2 PressurePressure is force per unit area.The SI-derived unit of pressure is the pascal (Pa): 1 Pa = 1 N/m2 = 1 kg/(m • s2) The torr and standard atmosphere (atm) are the only non-SI units used in this class.5.2 BarometerThe barometer was created in 1643 by Torricelli, who inverted a tube filled with mercury into a dish. At sea level, a column of mercury is 760 mm tall.Why doesn’t the Hg fall? The atmosphere is pushing it.§5.3 The Simple Gas Laws Boyle’s law, PV = k Charles’ Law, V = bT Avogadro’s Law, V = ank, b and a are constants. You don’t have to know these by name.§5.3 Boyle’s LawAt constant temperature, the pressure and volume of a gas are inversely proportional. PV = k, or P1V1 = P2V2 These data are ~350 years old!§5.3 Boyle’s LawGas pressure is a result of gas particles striking their container. As the pressure increases, the particles collide more frequently with the walls of the container.§5.3 Boyle’s LawThis plastic bottle was tightly sealed at 14,000 ft (4267 m), then brought down to 9000 ft (2743 m) then 1000 ft (305 m). 14,000 ft 9000 ft 1000 ftP1V1 = P2V2§5.3 Boyle’s Law and Ideal GasesAn ideal gas strictly obeys the ideal gas law (and by extension, Boyle’s Law).Real gases best obey the ideal gas law at low pressure and high temperature.In theory,PV = constant§5.3 DivingA diver takes a syringe with 16 mL of air from the surface to a depth where the volume becomes 7.5 mL. Assuming constant T, what is the pressure at this depth? If pressure increases by 1 atm for every 10. m of ocean how deep is the scuba diver ?P1V1 = P2V2 (1.00 atm) (16 mL) = P2 (7.5 mL) P2 = 2.1 atm (2.1 – 1.00) atm 10 m1 atm = 11 m§5.3 Charles’ LawAt constant pressure, volume and temperature are directly proportional.Like all matter, gases expand when heated.Use Kelvins throughout this class!Sealed cylinders with pistons and tied balloons demonstrate this law because P and n are constant. V = bT orCharles’ LawLord Kelvin used these data to extrapolate 0 K.All gases condense to liquids at some T > o K.§5.3 Charles’ LawA 500 mL balloon at 298 K placed in liquid nitrogen (77 K) shrinks. V2 = 0.13 LLiquid Nitrogen (LN2) Liquid nitrogen boils at -196 °C (77 K). The coldest temperature recorded on Earth was -89 °C.LN2 is used industrially as a coolant and a source of nitrogen gas.Liquid Nitrogen (LN2)Most objects immersed in LN2 solidify and become brittle.Skin contact with LN2 causes immediate frostbite; in small areas LN2 is applied to remove benign and malignant skin growths.§5.3 Avogadro’s LawEqual volumes of gases at the same temperature and pressure contain the same number of molecules."Thus, the number of molecules in a specific volume of gas is independent of the size or mass of the gas molecules.V1 = V2 n1 n2V = a • nn = moles gasa = a constantV = a • n§5.3 Avogadro’s LawInflating a balloon or adding gas to a cylinder with a moveable piston demonstrates Avogadro’s Law.For these objects (at constant P) adding more moles of gas increases volume ∴ V ∝ n.§5.4 Ideal Gas LawThe physical behavior of a gas sample can be described by 4 variables, any one of which can be calculated if the other three are known:PV = nRTDerived in 1834 by combining the simple gas lawsR is the universal gas constant; its value is:R = 0.08206 L ∙ atm K ∙ mol§5.4 Ideal Gas LawA 141 mL hand grenade holds 228.42 g TNT (227.13 g/mol). What pressure exists at 298 K when the TNT decomposes? 2C7H5N3O6(s)  3N2(g) + 5H2O(g) + 7CO(g) + 7C(s) 228.42 g TNT mol TNT 227.13 g TNT15 mol gas 2 mol TNT= 7.54260 mol gasP = (7.54260 mol)(0.08206 L ∙ atm)(298 K) (0.141 L) K ∙ mol= 1310 atmgrenade!!!§5.4 Ideal Gas LawA 0.50 L flask with 0.010 mol N2(g) is filled with 5.0 mol N2(l) at 77 K and 1.0 atm. Assuming constant V, what pressure was in the flask when warmed to 298 K?Which variables are constant? VconstantP2 = 1900 atmPV = nRT§5.5 STP and Molar VolumeSTP - standard temperature and pressure, 0 oC and 1 atmMolar volume – the volume of one mole of a gas. The molar volume of an ideal gas at STP is 22.42 L.V = nRT PIdeal Gas LawV = (1.00 mol)(0.08206 L ∙ atm)(273 K) = 22.4 L (1.00 atm) K ∙ mol§5.4 Ideal Gas LawA flask contains 1.0 mol F2 (g) at -73 °C. If another 1.0 mol of F2 (g) is added at constant pressure, what is the final temperature inside the flask?PV = nRTWhich variables are constant? P, VPV = nT Rn1T1 = n2T2constant1.0 mol · 200. K = 2.0 mol · T2T2 = 1.0 ⨯ 102 KThe moveable piston-cylinder below contained which gaseous reaction at constant P?1. A2(g) + B2(g) → 2AB(g)2. 2AB(g) + B2(g) → 2AB2(g)3. A(g) + B2(g) → AB2(g)4. 2AB2(g) → A2(g) + 2B2(g) →T = 150 KT = 300 K§5.5 Calculations at STPWhat volume of carbon monoxide at STP is produced when 15.4 g of TNT (227.13 g/mol) are detonated?2C7H5N3O6(s)  3N2(g) + 5H2O(g) + 7CO(g) + 7C(s) TNT15.4 g TNTmol TNT 227.13 g TNT7 mol CO2 mol TNT= 0.237 mol COV = (0.237 mol)(0.08206 L ∙ atm)(273 K) (1 atm) K ∙ mol= 5.31 L CO22.42 L CO1 mol COThe molar volume of an ideal