11

GasesGasesMr. WallyMr. Wally

ChemistryChemistry

2

Kinetic Theory of GasesKinetic Theory of Gases

► Molecules in random Molecules in random motion: strike each motion: strike each other and walls of other and walls of container. container.

► Force exerted on Force exerted on walls of container is walls of container is called called gas gas pressurepressure..

► Increase force of Increase force of collisions and # of collisions and # of collisions collisions increase increase gas pressure. gas pressure.

3

Who has gas?Who has gas?►Gas Pressure AnimationGas Pressure Animation

Properties of gases we will study: Volume, Temperature, Pressure, and Amount

4

Gas PressureGas Pressure►Units of pressure: Units of pressure: PascalPascal (SI base unit; (SI base unit;

N/mN/m22), ), kiloPascalkiloPascal (kPa), (kPa), atmosphereatmosphere (atm), (atm), millimeters of mercurymillimeters of mercury (mmHg), (mmHg), and and torrtorr. .

►Standard Temperature and Pressure Standard Temperature and Pressure (STP)(STP) At 0.0At 0.0ooC (273K)C (273K) At sea level: At sea level: 1 atm = 760 mmHg = 1 atm = 760 mmHg =

760 torr = 101.325 kPa = 101,325 Pa760 torr = 101.325 kPa = 101,325 Pa

5

Gas Pressure ConversionsGas Pressure Conversions

► Convert 0.357 atm to torrConvert 0.357 atm to torr► Convert .0670 torr to atmConvert .0670 torr to atm► Convert 147.2 kPa to torrConvert 147.2 kPa to torr► Convert 800.0 mm Hg to atmConvert 800.0 mm Hg to atm

6

Measuring Gas PressureMeasuring Gas Pressure►A A manometer manometer is used to measure gas is used to measure gas

pressure. pressure. A A barometerbarometer is used to measure is used to measure

atmospheric pressure. atmospheric pressure. A A sphygmomanometersphygmomanometer is used to is used to

measure blood pressure. measure blood pressure.

►A A tire gaugetire gauge is used to measure tire is used to measure tire pressure.pressure.

7

8

Manometer Problem # 1Manometer Problem # 11) 1) A closed manomter is filled with mercury and A closed manomter is filled with mercury and

connected to a container of nitrogen. The connected to a container of nitrogen. The difference in height of mercury in the two arms is difference in height of mercury in the two arms is 691 mmHg. What is the pressure of the nitrogen in 691 mmHg. What is the pressure of the nitrogen in

kPa?kPa?

9

Manometer Problem #2Manometer Problem #2► An open manometer is filled with mercury and An open manometer is filled with mercury and

connected to a container of hydrogen. The mercury connected to a container of hydrogen. The mercury is 66 mm higher in the arm of the tube connected is 66 mm higher in the arm of the tube connected to the gas. Atmospheric pressure is 97.7 kPa. to the gas. Atmospheric pressure is 97.7 kPa. What is the pressure of the gas in kPa? What is the pressure of the gas in kPa?

10

Manometer Problem #3Manometer Problem #3► On a certain day in lab, atmospheric pressure is On a certain day in lab, atmospheric pressure is

764.7 torr. A sample of gas is placed in a vessel 764.7 torr. A sample of gas is placed in a vessel attached to an open-end manometer. The level of attached to an open-end manometer. The level of mercury in the open-end arm is 136.4 mm and that mercury in the open-end arm is 136.4 mm and that in the arm in contact with the gas has a height of in the arm in contact with the gas has a height of 103.8 mm. What is the pressure of the gas in atm? 103.8 mm. What is the pressure of the gas in atm?

11

Two Closed Manometers: Two Closed Manometers: BarometerBarometer and and

SphygmomanometerSphygmomanometer