Chapter 10: Gases Part 1: Ideal GasesChapter 10: Gases Part 1: Ideal GasesExam 3 Concepts You Should Know:GasesPressurePressure and AltitudeMeasuring Atmospheric Pressure (What the Hell is a Torr Anyway?)Measuring Gas PressurePressure and MolesPressure and VolumePressure and TemperatureThe State of a GasThe Ideal Gas LawStandard Temperature and PressureChanges in P, V, and TPractice ProblemDensity and Molecular Weight of GasesHelium Balloons are Boring to Blow Up … but now we know why they floatPractice ProblemsWhat You Should KnowChapter 10: GasesPart 1: Ideal GasesCH110 FA11 SAS 1Prepare for Recitation October 20thALEKS Objective 8 due October 18thANGEL Quiz 8, October 20thLecture 22: October 12thLecture 23: October 14thLecture 24: October 17thRead: Ch. 10.1-10.9Additional Preparation: BLB 10: 5,23,30,45,71,75,82-84; Packet 10: 1-15BLB 25: 11,12,25Are you a visual learner?Intro.chem.okstate.eduCH110 FA11 SAS 2By the end of Today’s Lecture you should know:Pressure and Boyle’s LawTemperature and Charles’ LawAvogadro’s LawIdeal Gas LawDensity and Molecular WeightKEY QUESTIONS: THE BIG PICTUREChapter 10: GasesPart 1: Ideal GasesWhat does pressure mean?What types of molecules can be found as gasses?What state equation can we use to describe the properties of gasses?Remember: macroscopic properties come from microscopic originsHow does the energy of a molecule in a gas compare with intermolecular forces?How can we describe mixtures of gasses?How do real gasses differ from ideal gasses?Exam 3 Concepts You Should Know:CH110 FA11 SAS 3• What are the properties of ideal gases?• What is the partial pressure of a gas in a mixture?• How does kinetic molecular theory connect the microscopic properties of gases with observables?• How are real gases different from ideal gases?Chapter 10: GasesChapter 18: Atmospheric ChemistryChapter 13: (Aqueous) Solutions• What reactions occur in the atmosphere?• How do Chem 110 concepts show up in the atmosphere and environment?• What are electrolytes and how do we calculate the concentration of chemicals in solution?• What is meant by solubility and saturation?• What are colligative properties?• What is heat capacity?• What are the properties of liquids?• How do you use phase diagrams?Chapter 11: Intermolecular ForcesGasesCH110 FA11 SAS 4The gas phase is characterized by: • Molecules that are moving and ________• Intermolecular forces are ____________• Molecules with simple molecular formulasWhich elements exist as gases under ordinary conditions?Are metals ever found in gas molecules under ordinary condtions?• Spontaneous expansion to fill a container• High compressibility • The ability to form homogeneous mixtures (more at the end of Chapter 10)PressureCH110 FA11 SAS 5Standard Atmospheric Pressure:1 atm = 1.013 x105Pa1 atm = 14.7 lb·in21 atm = 760 mm Hg (torr)Atmospheric pressure depends on:Pressure is:• Caused by molecular collisions• Dependent on density and temperature: Earth’s gravity affects the density of a gas, and therefore affects its pressure.Pressure:Pressure and AltitudeCH110 FA11 SAS 6• Pressure at a given altitude depends on the weight of the gas above itAltitude(km)P(atm)Collision Frequency (s-1)0 1 101050 10-3107100 10-6103200 10-131Measuring Atmospheric Pressure(What the Hell is a Torr Anyway?)CH110 FA11 SAS 7The first measurement of pressure was made with a barometer by Torricelli in the 1600s.• Force from atmosphere must balance force from Hg in column.• Patmproportional to height of column:Under standard conditions h = 760 mmNote: Height of column depends on what liquid is used. 1 atm = 10 m H20Measuring Gas PressureCH110 FA11 SAS 8A Mercury Manometer can be used to measure the pressure of a gas in a closed container:Pressure and MolesCH110 FA11 SAS 9The state of a gas is described by:P = pressureV = volume of containerT = temperature (in Kelvin)n = moles of gasAvogadro’s Law:The volume of gas at constant temperature and pressure is proportional to the number of moles of gas present. (V/n = constant)Pressure and VolumeCH110 FA11 SAS 10The state of a gas is described by:P = pressureV = volume of containerT = temperature (in Kelvin)n = moles of gasBoyle’s Law:At constant temperature and number of moles of gas, the product of the pressure and volume is a constant. (PV = constant)1 atm 2 atm 4 atm½ V1 V ¼ VPressure and TemperatureCH110 FA11 SAS 11The state of a gas is described by:P = pressureV = volume of containerT = temperature (in Kelvin)n = moles of gasCharles’ Law:At constant pressure and number of moles of gas, the volume is proportional to the absolute temperature. (V/T = constant)Absolute Temperature in Kelvin (K):K = oC + 273.15The State of a GasCH110 FA11 SAS 12At constant T, P: V/n = constantPV1/PVnVAt constant T, n: PV = constantAt constant P, n: V/T = constantTVThe Ideal Gas LawCH110 FA11 SAS 13PV = nRTgas constantBeware of R!! (units are always important)R = 0.08206 L·atm·mol-1K-1R = 8.314 J ·mol-1K-1Avogadro V = constant (fixed P & T)nBoyle PV = constant (fixed T & n)Charles V = constant (fixed P & n)TAll can be described with one relationshipStandard Temperature and PressureCH110 FA11 SAS 14The Ideal Gas Law is a State FunctionPV = nRTSTP: Standard Temperature and Pressure is frequently encountered and is defined asT = 0oC (273 K) P = 1 atmPractice Problem:What is the volume (V) occupied by 1.00 mole of gas at exactly 0oC and 1 atm?Changes in P, V, and TCH110 FA11 SAS 15Given: initial conditions (Pi, Vi, Ti) and final conditions for two quantitiesFind: the value for the 3rdfinal valuePiViPfVfTiTfn R== n RPiViTiPfVfTf=Practice ProblemCH110 FA11 SAS 16The gas in a 750 mL vessel at 105 atm and 27 oC is expanded into a vessel of 54.5 L and –10 oC. What is the final P ?A. 0.0051 atmB. 0.014 atmC. 0.77 atmD. 1.3 atmE. 73 atmDensity and Molecular Weight of GasesCH110 FA11 SAS 17PV = nRTn moles = Therefore… PV = mMmMm (mass) gM (molar mass) g/molRTDensity (d) is: d =mVdensity ∝ molar mass=MP mRT V=rearrangeVolume (in L)Number of moles in a gas:Helium Balloons are Boring to Blow Up… but now we know why they floatCH110 FA11 SAS 18What is the density of He gas in g/L at 21oC and 752 torr?Under these conditions, the density of air is 1.188 g/L. The mass difference between 1L of He and 1L of air is:This is the buoyant (lifting force) of He per L.Practice ProblemsCH110 FA11 SAS 19Which one of the following samples contains the largest
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