APChemNTIIIKEY Currently,thereisamassivenaturalgasleakattheAlisoCanyonstoragefacilityin PorterRanch,CalifornianearLosAngeles.Gasisstoredbyinjectingitdeepunder groundintodepletedgaswells.Initiallythewellwasleakingover44,000kilograms ofnaturalgasanhour! Thestoragefacilitycontainsapproximately22billioncubicfeet(6.3x1011L) ofgas.Atthedepthwherethegasisconfinedpressuresare20atmanda temperatureof147oC.Ifthegasfacilityweretocompletelyleaktothe surface,findwhatvolumethegaswouldhaveatnormalpressuresand temperatures(1atmand25oC). ! ! ! ! UseCombinedGasLaw !! ! = !! ! ! ! 20 ππ‘π β 6.3 β 10!! πΏ 1 ππ‘π β π! = β΄ π! = 8.9 β 10!" πΏ (147 + 273)πΎ 25 + 273 πΎ Naturalgasispredominatelymethane(CH4).Methaneis25timesmore potentasagreenhousegasthancarbondioxide.Usingthecombustionof octaneasamodelforgasoline,findthelitersofgasolinethatwouldneedto beburnttoproducecarbondioxideofequivalentgreenhousegaseffectto volumeofmethanereleasedifthestoragefacilitycompletelyemptied.Use 1atmand25oC.Thedensityofgasolineis770g/L. Combustionofoctane 2 C8H18 + 25O2 ! 18 H2O + 16 CO2 Use PV = nRT to find moles of Methane !"#β! 1 ππ‘π β 8.9 β 10!" πΏ = π β 0.0821!"#β! β 298πΎ β΄ π = 3.6 β 10!! Multiple moles of metane by 25 because 1 mole CH4 = 25 mole CO2 πππππ πΆπ! = 9.0 β 10!" Use stoichiometry to convert moles CO2 to L of gasoline (octane) 9.0 β 10!" πππ πΆπ! 2 πππ πΆ! π»!" 114.26 π 1 πΏ β β β = 1.7 β 10!! πΏ 16 πππ πΆπ! 1 πππ 770 π (Incidentally, this is enough for me to drive my car the distance to the moon and back 3,800 times!) A 2L tank contains 10g of each of these gasses at 400oC: Methanol (CH3OH), Carbon monoxide (CO), and Hydrogen (H2). Find the total pressure in the tank. Find total moles 10π πΆπ»! ππ» 10π πΆπ 10π π»! + + = 5.6 πππ 32.05 π β πππ !! 28.01 π β πππ !! 2.02 π β πππ !! Use total moles in PV = nRT !"#β! π!"! β 2πΏ = 5.6πππ β 0.0821 !"#β! β 400 + 273 πΎ β΄ π!"! = 160 ππ‘π Find the partial pressure of each gas. Use Law of Partial Pressures π! π! π! = = π!"! π!"! π!"! Methanol π!!! !" . 31 πππ = β΄ π!!! !" = 8.9 ππ‘π 160 ππ‘π 5.6 πππ Carbon Monoxide π!" . 36 πππ = β΄ π!! = 10.3 ππ‘π 160 ππ‘π 5.6 πππ Hydrogen π!! 5.0 πππ = β΄ π!! = 140 ππ‘π 160 ππ‘π 5.6 πππ How do the average kinetic energies of each gas compare. Explain. The average kinetic energies are all equal because all three gasses are at the same temperature. How do the average molecular speeds of each gas compare. Explain. KE = 1/2mv2, so at a given temperature, the lightest gases will be moving the fastest. Hydrogen will have the highest average velocity followed by carbon monoxide followed by methanol. The temperature was lowered to below the boiling point of methanol. Small amounts of H2 gas and CO gas were found to be dissolved in the liquid. Which of the two gases would you expect to be more soluble in liquid methanol? The forces between hydrogen gas and methanol would be weak London dispersion forces because hydrogen is a nonpolar molecule. The London dispersion forces between carbon monoxide and methanol would be stronger because carbon monoxide has more electrons (more polarizable). Additionally, both carbon monoxide and methanol are polar molecules so dipole-dipole interactions could form. With stronger intermolecular forces between carbon monoxide and methanol, more carbon monoxide would be expected to dissolve than hydrogen C2H4(g) in a tank is heated from 300 to 450K and the pressure is observed to increase. Describe at the molecular level why this occurs. Pressure is force per unit area. Force is created when gas molecules collide with the walls of a container. As the temperature increases, the average velocity of the molecules will increase. This will increase the frequencies the molecules collide with the walls of the tank. The increased average velocity will also increase the average kinetic energy of the molecules. When they strike the walls of the tank, they will do so with more force. Once the tank is at 450K, HCl(g) is injected into the tank. This reaction occurs: C2H4(g) + HCl(g) ! C2H5Cl(g) The pressure on the tank initially increases, but as the reaction occurs, the pressure decreases. Describe at the molecular level why this occurs. Initially, the additional gas molecules from the added HCl will create additional collisions and therefore more pressure in the container. However, as the reaction proceeds, 2 gas molecules are consumed (1C2H4 and 1 HCl) but only one is produced (1 C2H5Cl), which reduced the number of molecules of gas and therefore the pressure.
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