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Unformatted text preview: Pressure
Force per unit area. Gas molecules fill container. Molecules move around and hit sides. Collisions are the force. Container has the area. Measured with a barometer. Chapter 5
The Gas Laws 1 2 Vacuum Barometer
760 mm Hg The pressure of the atmosphere at sea level will hold a column of mercury 760 mm Hg. 1 atm = 760 mm Hg Gas Manometer
Column of mercury to measure pressure. h is how much lower the pressure is than outside. 1 atm Pressure h 3 4 Manometer
h is how much higher the gas pressure is than the atmosphere. Units of pressure
1 atmosphere = 760 mm Hg 1 mm Hg = 1 torr 1 atm = 101,325 Pascals = 101.325 kPa Can make conversion factors from these. What is 724 mm Hg in kPa? in torr? in atm?
6 h Gas
5 1 The Gas Laws
Boyle's Law Pressure and volume are inversely related at constant temperature. PV= k As one goes up, the other goes down. P1V1 = P2 V2 Graphically
7 8 V P (at constant T) 22.41 L atm V Slope = k PV O2 CO2 9 1/P (at constant T) 10 P (at constant T) Examples
20.5 L of nitrogen at 25C and 742 torr are compressed to 9.8 atm at constant T. What is the new volume? 30.6 mL of carbon dioxide at 740 torr is expanded at constant temperature to 750 mL. What is the final pressure...
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