Kinetic Theory of Gases Chemistry Mrs Coyle Part

Kinetic Theory of Gases Chemistry Mrs. Coyle

Part I- Kinetic Molecular Theory and Pressure

Gas Phase

State Variables of a Gas: describe the State of a Gas (PVT) • Pressure (P) • Volume (V) • Temperature (T) SI Unit Pascals Pa m 3 Kelvin • Amount of gas molecules mol

Standard Temperature and Pressure (STP) • 1 atm =760 mm. Hg (torr) = 101. 3 k. Pa • 273 K =0 0 C

Pressure P= F A Units of Pressure: pascal, mm. Hg, atm 1 Pa = 1 N/m 2

Kinetic Molecular Theory (KMT)Ideal Gases 1. The volume of the individual particles of a gas are negligible compared to the distances between them. 2. The particles are in constant motion. The collisions of the particles with the walls of the container cause pressure.

KMT Continued 3. The particles are assumed not to exert attracting or repelling forces on each other. The collisions are perfectly elastic. No kinetic energy is lost before and after the collision. 4. The average kinetic energy of a gas is directly proportional to the Kelvin temperature.

Simulation • http: //www 2. biglobe. ne. jp/~norimari/scienc e/Java. App/Mole/e-gas. html

Part II • Temperature and KE • Measuring Pressure: Barometer, Manometer

Temperature • How hot – cold • Average kinetic energy of molecules.

Temperature Scales Freezing Point of Water • • • Celsius 0 Kelvin 273 Fahrenheit 32 K=273+C F=(9/5)C +32 Boiling Point of Water 100 373 212 (absolute zero: 0 K) • When you increase T by one degree C, how many K do you increase by?

Kinetic Energy • KE= ½ m v 2 • v speed, m mass • Example: speed of oxygen molecule at 25 o. C = 443 m/s

Manometer- Open End PC=PB PA= Atmospheric Pressure PB=PA+ PAB is measured in mm. Hg (torr) PAB is called gauge pressure. Gas Sample

Manometer- Closed End “Barometer” PC=PB PA= 0 atm PB= PAB Gas Sample