CHEM 1211 Lecture 23 Outline of Last Lecture I Ethene Double Bond II Ethyne Triple Bond III Molecualr Orbital Theory IV BO in MO V Excited States Outline of Current Lecture I Behaviors of Gases II General Properties of Gas III Pressure IV Boyle s Law V Charles s Law VI General Gas Law Current Lecture NH2 3 C N C N 5 C NH2 N NH2 Clicker Question One How many sigma bonds Clicker Question Two How many pi bonds Clicker Question Three Hybridization of Ring N A sp B sp2 C sp3 D sp3d 4 15 single bonds 3 double bonds I II III IV E sp3d2 Clicker Question Four Hybridization of N on NH2 A sp B sp2 C sp3 D sp3d E sp3d2 Clicker Question Five What is the bond angle on C 120 Clicker Question Six What is the idealized H N H bond angle 109 5 Behaviors of Gases Airbags fill with N2 gas in an accident generated by rapid decomposition of sodium azide NaN3 2NaN3 s 2Na s 3N2 g Ideal gas where molecules are independent collisions are elastic and do not stick energy is conserved General Properties of Gas Large collection of particles in constant random motion not static Occupy containers uniformly and completely Diffuse to form homogenous mixture Most of Volume is empty space V Volume L T Temperature K n Amount moles P Pressure atmospheres V T P state functions n extensive property Pressure Atmospheric pressure is measured with a barometer mercury filled M dxv P force area m x g A g x d x v A Volume x3 Area x2 height x P g x d x h Boyle s Law Gases are compressible V VI Pressure of system of gas particles in inversely proportional to volume of fixed number of moles at a constant temperature P1V1 P2V2 N2 has a pressure of 67 5 mm Hg in a 500 Ml flask What is the pressure of this gas sample when transferred to a 125 ml flask at the same temperature P1V1 P2V2 P1 67 5 mm Hg P2 500 mL V1 V2 125 mL 67 5 mm Hg 500 mL 2 70 x 102 mm Hg 125 mL Charles s Law Balloons immersed in N2 at 196 C will shrink as it cools Volume is directly proportional to absolute temperature of a fixed number of moles at constant pressure V1 V2 T1 T2 Use absolute scale K C 273 15 A 5 0 ml sample of CO2 is enclosed in a gas tight syringe at 22 C If the syringe is immersed in an ice bath 0 C What is the new gas volume assuming the pressure is constant 4 6 mL General Gas Law Combination of Boyle s Law and Charles s Law P1 x V1 P2 x V2 combined gas law T1 T2 Flask A has CO2 with a volume of 25 0 mL at 20 5 C the pressure is 436 5 mm Hg To find V of Flask B you move CO2 to the flask and find that the pressure is 94 3 mm HG at 24 5 C What is the Volume of Flask B 117 mL
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