Gases Mr. Wally Chemistry
Molecules in random motion: strike each other and walls of container. Force exerted on walls of container is called gas pressure. Increase force of collisions and # of collisions increase gas pressure. Kinetic Theory of Gases
Who has gas? • Gas Pressure Animation Properties of gases we will study: Volume, Temperature, Pressure, and Amount
Gas Pressure • Units of pressure: Pascal (SI base unit; N/m2), kiloPascal (kPa), atmosphere (atm), millimeters of mercury (mmHg), and torr. • Standard Temperature and Pressure (STP) • At 0.0oC (273K) • At sea level: 1 atm = 760 mmHg = 760 torr = 101.325 kPa = 101,325 Pa
Gas Pressure Conversions • Convert 0.357 atm to torr • Convert .0670 torr to atm • Convert 147.2 kPa to torr • Convert 800.0 mm Hg to atm
Measuring Gas Pressure • A manometer is used to measure gas pressure. • A barometer is used to measure atmospheric pressure. • A sphygmomanometer is used to measure blood pressure. • A tire gauge is used to measure tire pressure.
Manometer Problem # 1 1) A closed manomter is filled with mercury and connected to a container of nitrogen. The difference in height of mercury in the two arms is 691 mmHg. What is the pressure of the nitrogen in kPa?
Manometer Problem #2 • An open manometer is filled with mercury and connected to a container of hydrogen. The mercury is 66 mm higher in the arm of the tube connected to the gas. Atmospheric pressure is 97.7 kPa. What is the pressure of the gas in kPa?
Manometer Problem #3 • On a certain day in lab, atmospheric pressure is 764.7 torr. A sample of gas is placed in a vessel attached to an open-end manometer. The level of mercury in the open-end arm is 136.4 mm and that in the arm in contact with the gas has a height of 103.8 mm. What is the pressure of the gas in atm?