CHEM 1211 Lecture 23Outline of Last Lecture I. Ethene: Double BondII. Ethyne: Triple BondIII. Molecualr Orbital TheoryIV. BO in MOV. Excited StatesOutline of Current Lecture I. Behaviors of GasesII. General Properties of GasIII. PressureIV. Boyle’s LawV. Charles’s LawVI. General Gas LawCurrent Lecture: NH2 #3 CN NC #5 C #4NH2 N NH2Clicker Question One: How many sigma bonds? 15 (single bonds)Clicker Question Two:How many pi-bonds? 3 (double bonds)Clicker Question Three:Hybridization of Ring N?A. spB. sp2C. sp3D. sp3dE. sp3d2Clicker Question Four:Hybridization of N on NH2?A. spB. sp2C. sp3D. sp3dE. sp3d2Clicker Question Five:What is the bond angle on C? 120°Clicker Question Six:What is the idealized H – N – H bond angle? 109.5°I. 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. II. 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 propertyIII. Pressure- Atmospheric pressure is measured with a barometer (mercury filled)M = d x vP = force / area = (m x g / A) = (g x d x v / A)Volume (x3) / Area (x2) = height (x)**P = g x d x h**IV. Boyle’s Law- Gases are compressible- 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 = P2V2P1: 67.5 mm HgP2: 500. mLV1: ?V2: 125 mL(67.5 mm Hg)(500. mL) = 2.70 x 102 mm Hg (125 mL)V. 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 pressureV1 = V2T1 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 VI. General Gas Law- Combination of Boyle’s Law and Charles’s LawP1 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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