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KeyHOMEWORK for Chapter 11: Gases11.1 Properties of Gases (Read pgs. 327 - 330 in the chemistry textbook)11.2 Gas Pressure (Read pgs. 330 - 332 in the chemistry textbook) What is the Kinetic Molecular Theory (KMT) of Gases?A theory that about the behavior of gas particles: 5 tenets (principles) Small, random movement, high velocity VERY small IMFs (often considered nonexistent) Average EK is proportional to Kelvin temperatureVolume occupied by the individual gas particles is VERY small (considered negligible)Constant motion, straight-line paths What are the 4 gas properties and their units?PROPERTIESUNITSPressure (P)atmospheres (atm)Torricelli (torr)millimeters of mercury (mmHg)Pascals (Pa)kilopascals (kPa)Volume (V)Liters (L), milliliters (mL)Temperature (T)Kelvin (K)Amount in moles(n)moles (n)3. Explain each of the 4 gas properties.PROPERTIESExplanationGas Pressurethe force of the collisions of gas molecules with the walls of the containerAtmospheric pressurethe force of the collisions of the gas molecules making up the atmosphere with whatever they touchmore collisions = more pressureless collisions = less pressureVolumethe space occupied by the gas – if the gas is in a container the volume of the gas is equal to the volume of the containerTemperaturedetermines the average EK and therefore the number of collisions of the particlesAmountthe quantity of gas present in the container4. Use the KMT to explain why a gas completely fills a container of any size and shape.Gas particles are constantly moving at high speeds in random, butstraight-line directions. They would travel indefinitely if nothingstopped them. Eventually they encounter the walls of the container– at which point the volume being occupied by all the gas particlesis equal to the volume of the container5. Identify the property of a gas that is described by each of the following:Temperaturea) increases the EK of gas particlesPressureb) the force of the gas particles hitting the walls of the containerVolumec) the space that is occupied by a gas6. Use the KMT to explain each of the following: Gases move faster at higher temperatures.the average EK of a gas is proportional to the Kelvin temperature – as T↑ so does the average EK of the gas particlesGases can be compressed more easily than liquids or solids.individual gas particles are considered to occupy NO space, and to be very far apartGases have low densities.the IMFs between individual gas particles is considered negligible – so the particles are free to move away from one another – less mass per unit of space = lower densityA container of nonstick cooking spray explodes when thrown into a fire.at higher temperatures the gas particles collide more often with the walls of the container – eventually the number of collisions creates a pressure greater than can be borne by the walls of the container – so it “explodes”6. Continued:The air in a hot-air balloon is heated to make the balloon rise.the higher temperature inside the balloon makes the gas particles move away from each other so that the gas inside the balloon is less dense than the gas of the surrounding atmosphereYou can smell the odor of cooking onions from far away.gas molecules move at very high velocities in random, straight-line directions – eventually they will fill the entire house (or even the entire outside area surrounding a bakery)7. Identify the property of a gas that is measured in each of the following.Temperaturea) 350 KVolumeb) the space occupied by a gasAmountc) 2.00 mole of O2Pressured) the force of gas particles colliding with the walls of the containerTemperaturea) 425 KPressureb) 1.0 atmVolumec) 10.0 LAmountd) 0.50 mol of He8. What is the definition of pressure?the force acting on a certain areaPressure (P) = ForceArea9. What is a barometer?a device used for measuring atmospheric pressure10. How does a barometer work? -221568802The pressure of the earth’s atmosphere pushing down on the surface of the mercury in the open dish will “push” the mercury a certain height up theevacuated tube. The greater the pressure of the atmosphere thehigher up the tube the mercury will be pushed – and vice versa.The units used to measure the height of the column can vary with the type of liquid in the barometer and the measurement system being used.At STP the earth’s atmosphere will push a column of mercury up 760 millimeters – o r – 760 mmHg11. What is STP?Standard Temperature and Pressure at sea levelStandard Temperature = 0oC, or 273 Kelvin Standard Pressure = 1 atmthis means that at sea level, when the temperature is 0oC the pressure of the earth’s atmosphere is defined as 1 atmosphere12. Why isn’t standard pressure 760 mmHg?IT IS!!!! Standard pressure is measured in many different units, but it is customary (and simpler) to use “atmospheres” because it equals 113. What are some other “units” of standard pressure?UnitsAbbreviation1 atmosphere1 atm760 millimeters of mercury760 mmHg29.9 inches of mercury29.9 in. Hg760 torricelli760 torr101,325 Pascal101,325 Pa*101.325 kilopascal101.325 kPa14.70 pounds per square inch14.70 lb/ in2* The official SI unit of pressure14. Is atmospheric pressure the same at all location on Earth? Explain.NOThe pressure is greatest at the lowest spots on Earth and least at the highest spots.Example: top of Mt. Everest ≈ 20,500 ft above sea level ≈ 33 kPabottom of Death Valley = 282 ft below sea level ≈ 105 kPa15. Why does the height of a column of mercury in a barometer change from day to day?b/c the atmospheric pressure changes day to dayon days with higher atmospheric pressure the column is higher, and vice-versa16. Water is cheaper and safer to use than mercury, and, it will rise and fall with daily changes in atmospheric pressure. Why aren't barometers commonly made out of water? HINT: Mercury is approximately 13.5 times more dense than water. 29.9 inches × 13.5 = 403.65 inches ÷ 1 ft12 inches = 33.6 fta water barometer would have to be over 30 foot tall!!17. An oxygen tank contains oxygen (O2) at a presure of 2.00 atm. What is the pressure in the tank in terms of the following units?(a) torr2.00 atm ( 760 torr1 atm ) = 1520 torr(b) kPa2.00 atm ( 101.325 kPa1 atm ) = 203 kPa (c) mmHg2.00 atm ( 760 mmHg1 atm ) = 1520 mmHg(d) lb/in22.00 atm ( 14.70lbin21 atm ) = 29.4 lbin217. On a climb up Mt. Whtney, the atmospheric pressure drops to 467 mmHg. What is the pressure in terms of the following units?(a) atm467 mmHg ( 1 atm760 mmHg ) = 0.614 atm(b) torr467 mmHg ( 760 torr760 mmHg ) = 467 torr(c) Pa467 mmHg ( 101,325 Pa760 mmHg ) = 62, 300 Pa(d) in. Hg 467 mmHg ( 29.9 in.Hg760 mmHg ) = 18.4 lbin2 ................
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