110_Fa11_LUZ-week8ST (1)

# 110_Fa11_LUZ-week8ST (1) - Week 8 Gas Molecules...

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Jensen Chem 110 Chap 10 Page: 1 Week 8: Lectures 22 – 24 Lecture 22: W 10/12 Lecture 23: F 10/14 (Special lecture by Dr. Ben Lear) Lecture 24: M 10/17 Reading: BLB Ch 10.1 – 10.9 Homework: BLB 10: 23, 30, 45, 5, 71, 75, 82, 83, 84; Supp 10: 1 – 15 Reminder: No Angel Quiz on Thur 10/13 ALEKS Objective 8 due on Tue 10/18 Angel Quiz 8 due on Thur 10/20 Jensen Office Hour: 501 Chemistry Building Thursday 10/13: cancelled Tuesday 10/18: 10:30 – 11:30 am Jensen Chem 110 Chap 10 Page: 2 Gas Molecules’ Characteristics ! Gas molecules are constantly moving expand in whatever volume is available mix completely with one another ! They are far apart (10 times as far as they are big) can be easily compressed ! They move in straight lines ! They collide with each other ! They collide with walls: pressure ! Higher temperature yields faster motion ! Lower temperature yields slower motion and eventually condensation Gases are described in terms of: pressure (P), temperature (T), volume (V), # moles (n) All gases behave similarly at low pressure Gases will mix in all proportions with other gases to form homogeneous mixtures

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Jensen Chem 110 Chap 10 Page: 3 Pressure Pressure: force per unit area Force: Kg•m•s –2 , or Newton (N); Unit area: m 2 • SI unit for pressure: 1 N•m –2 = 1 Pa (Pascal) Standard Atmospheric Pressure**: 1 atm = 1.013 x 10 5 Pa 1 atm = 760 torr (or mm Hg) [1 atm = 14.7 lb/in 2 ] Jensen Chem 110 Chap 10 Page: 4 Measuring Pressure Barometer used to measure P atm The key idea is balance force on area P atm " height (h) of column of liquid Measure P in terms of height of Hg 1 atm = 760 torr “=” 760 mm Hg [ know this conversion!] P atm P Hg P atm = P Hg d l = density of liquid (here: Hg) g = gravitational constant P atm = constant x h P atm = F atm /A P Hg = F l /A = gd l h so,
Jensen Chem 110 Chap 10 Page: 5 Mercury Manometer Used to measure the difference in pressure between open or closed end and that of a gas in a vessel. Closed Ended: P g = h (mm Hg) Open Ended: Which P is greater? P gas = P atm __ P h P gas = P atm __ P h Jensen Chem 110 Chap 10 Page: 6 Example: The height of the column of mercury in the open-ended manometer shown is found to be 65 mm. If the external pressure is 1.06 atm, what is the gas pressure inside the bulb? A. 0.85 atm B. 0.97 atm C. 1.15 atm D. 1.71 atm E. The pressure cannot be determined from the information given.

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Jensen Chem 110 Chap 10 Page: 7 Understanding Gases State of gas is described by: n = moles of gas P = pressure V = volume of container
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## This note was uploaded on 01/18/2012 for the course CHEM 110 taught by Professor Hofmann,brucerob during the Fall '08 term at Penn State.

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110_Fa11_LUZ-week8ST (1) - Week 8 Gas Molecules...

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