Gases Physical Characteristics of Gases KMT Postulate 1

Gases Physical Characteristics of Gases

KMT – Postulate 1 Gases consist of large numbers of tiny particles that are far apart relative to their size. Kinetic Molecular Theory

Postulate 2 Collisions between gas particles and container walls are elastic. • No net loss of energy. • Energy is transferred between particles in collisions. Kinetic Molecular Theory

Postulate 3 Particles are in continuous, rapid and random motion. • They possess kinetic energy Kinetic Molecular Theory

Postulate 4 There are no forces of attraction or repulsion between gas particles. Kinetic Molecular Theory

Postulate 5 The average kinetic energy of gas molecules depends on the temperature of the gas. Kinetic Molecular Theory

Pressure Depending on the situation, pressure may be measured in: • • atmospheres (atm) torr (torr) named in honor of Torricelli millimeters of mercury (mm Hg -or- mm) kilopascals (k. Pa) 1 atm = 760 torr = 760 mm Hg = 101. 325 k. Pa

Pressure 1 atm = 760 torr = 760 mm Hg = 101. 325 k. Pa 1. Convert 2. 5 atm to mm Hg 2. 5 atm 1, 900 mm Hg 2. Convert 455 mm Hg to torr 455 mm Hg 455 torr

Pressure 1 atm = 760 torr = 760 mm Hg = 101. 325 k. Pa 3. Convert 165 k. Pa to atm 165 k. Pa 1. 63 atm 4. Convert 825 mm Hg to k. Pa 825 mm Hg 110. k. Pa

Temperature When working with gases and gas law calculations, temperature MUST BE in Kelvin. K = °C + 273 5 remember: °C = (°F +40) – 40 9

Standard Conditions Standard Temperature and Pressure (abbreviated STP): O°C 1 atm