Kinetic-Molecular Theory (KMT) Basic Principles of KMT Absolute temperature Pressure Diffusion

What is KMT? * Based on the research of Robert Boyle (1627 – 1691) A theory that envisions molecules in motion Best describes properties and behaviors of gases * Imagines particles of a gas like billiard balls, moving and crashing into each and the walls of a container in a three-dimensional space.

6 Basic Principles of KMT 1. Gases consist of tiny (submicroscopic) particles.

2. Gas particles are very far apart; the volume occupied by a gas consists mostly of empty space (typically about 99.9% empty). 3. Gas particles are not attracted to each other (like ions are.)

4. Gas particles move randomly in all directions, traveling in straight lines. * Gas molecules travel at very high speeds, about 6000 km/hr (~2700 mi/hr) The higher the average speed of the particles, the higher the temperature of that substance.  Absolute temperature: T based on average particle speed; measured in Kelvin (K)  Absolute zero (0 K): particles are not moving; there is no T below 0 K. K = °C + 273

6. Gas particles collide with each other and with the walls of the container without losing energy. Pressure = the collision of gas particles with a surface; force per unit area

Diffusion = spontaneous mixing of two gases or liquids because particles move randomly Effusion = process by which gas molecules pass through a small opening form a container at higher pressure to one of lower pressure atmospheric pressure = mass of the atmosphere pressing downward at a point; pressure experienced by objects on Earth as a result of the layer of air surrounding our planet 1 atm = 760 torr = 760 mm Hg = 101,325 Pa (Pascal—SI unit) at 0°C; sea level is 1 atm of pressure