Kinetic Theory All matter consist of small particles. All matter consist of small particles. The molecules are in constant, random, rapid motion. The molecules are in constant, random, rapid motion. All collisions are elastic (no net loss of energy). All collisions are elastic (no net loss of energy).

As temperature increases, the molecules’ velocity increases, increasing the pressure on the container.

States of Matter StateShapeVolumeCompressible?Flows? Solid Liquid Gas Definite Definite No IndefiniteDefinite No Indefinite Indefinite yes No yes yes

Vapor pressure The pressure produced when vapor particles above a liquid collide with the container walls; a dynamic equilibrium exists between the liquid and vapor. The pressure produced when vapor particles above a liquid collide with the container walls; a dynamic equilibrium exists between the liquid and vapor. Vapor pressure increases with temperature. Vapor pressure increases with temperature. A substance with weak intermolecular forces has a high vapor pressure and low boiling point (volatile)- alcohols, ether. A substance with weak intermolecular forces has a high vapor pressure and low boiling point (volatile)- alcohols, ether. A substance with strong intermolecular forces has a low vapor pressure and high boiling point (nonvolatile)- water, molasses, glycerol. A substance with strong intermolecular forces has a low vapor pressure and high boiling point (nonvolatile)- water, molasses, glycerol.

Phase Diagram Critical point- above this temperature, no amount of pressure can liquefy it. Triple point- all three phases are at equilibrium

Paraffin Water

Diffusion The spontaneous spreading of particles The spontaneous spreading of particles Rate of diffusion depends on the velocities and masses of the molecules. Rate of diffusion depends on the velocities and masses of the molecules. Effusion- the process by which a gas escapes from a small hole in a container. Effusion- the process by which a gas escapes from a small hole in a container.

Two substances at the same temperature should have the same average kinetic energies. Two substances at the same temperature should have the same average kinetic energies. KE 1 =KE 2 and KE = ½ mv 2 KE 1 =KE 2 and KE = ½ mv 2 ½ m 1 v 1 2 = ½ m 2 v 2 2 ½ m 1 v 1 2 = ½ m 2 v 2 2 m 1 v 1 2 = m 2 v 2 2 m 1 v 1 2 = m 2 v 2 2 v 1 2 = m 2 or v 1 2 = m 2 or v 2 2 m 1 v 2 2 m 1

Graham’s Law of Diffusion The relative rates at which two gases (at the same temperature and pressure) will diffuse vary inversely as the square root of the molecular masses of the gases. The relative rates at which two gases (at the same temperature and pressure) will diffuse vary inversely as the square root of the molecular masses of the gases.

Compute the relative rate of diffusion of helium and argon. He diffuses 3.16 times faster than Ar.

Compare the rates of diffusion of O 2 and N 2. Compare the rates of diffusion of O 2 and N 2. Since the lighter gas always diffuses faster, N 2 diffuses 1.07 times faster than O 2. Since the lighter gas always diffuses faster, N 2 diffuses 1.07 times faster than O 2.

You try it... Compare the rates of diffusion of sulfur trioxide and nitrogen monoxide. Compare the rates of diffusion of sulfur trioxide and nitrogen monoxide. NO diffuses 1.63 times faster than SO 3. NO diffuses 1.63 times faster than SO 3.

Gas #1 weighs 42.0 g/mol and diffuses at a rate of 5.65 m/s through an opening in a jar. Gas #2 weighs g/mol. At what rate would it pass through the same opening? 5.65m/s = 2.45 v m/s = v 2

Diffusion Lab NH 4 OH  H 2 O + NH 3  NH 4 OH  H 2 O + NH 3  HClNH 3