GASES, LIQUIDS, AND SOLIDS STATES OF MATTER

GASES What are gases? Gases have no definite shape or volume. Scientists starting studying gases in depth in the 1600’s. It wasn’t until the mid 1800s that our current understanding started to crystalize

KINETIC-MOLECULAR THEORY According to kinetic-molecular theory, all gases are made up particles. According to kinetic-molecular theory, all gases have particles with similar properties.

PARTICLE PROPERTIES OF GASES: PARTICLE SIZE All gases are made up small particles separated by large amounts of empty space. Because particles are far apart, there are no attractive or repulsive force between the individual particles.

PARTICLE PROPERTIES OF GASES: PARTICLE MOTION Gas particles are in random, straight line motion. They only change direction when they strike other particles. Collisions between particles are assumed to be elastic No energy is assumed to be gained or lost during the collision

PARTICLE PROPERTIES OF GASES: PARTICLE ENERGY Particles are assumed to moving with a certain amount of energy that depends on their mass and velocity. The equation for this is: KE = Kinetic energy m = mass v = velocity- notice that v is more important than m. Why?

PARTICLE ENERGY AND TEMPERATURE Temperature is a measure of the average kinetic energy of all particles in a system.

USING K-M THEORY TO EXPLAIN GAS BEHAVIOR Density of Gases: Compressibility and Expandability:

USING K-M THEORY TO EXPLAIN GAS BEHAVIOR Diffusion: The movement of one material through another. Light particles tend to diffuse faster than heavy ones. Why? Remember

EFFUSION: GAS ESCAPING THROUGH A SMALL OPENING. Graham’s Law of Effusion: What effuses faster H 2 or Cl 2 ?

GASES AND GAS PRESSURE Pressure is defined as force applied per unit area. Because gas particles are moving and have mass, they apply force on the surface of an object.

MEASURING AIR PRESSURE Compared to 1 atm Compared to 1kPa Kilopascal (kPa) kPax Millimeters of mercury (mm Hg) 760 mm Hg7.501 mm Hg Torr 760 torr7.501 torr Pounds per square inch psi or lb/in psi0.145 psi atmosphere (atm) x atm

DALTON’S LAW OF PARTIAL PRESSURE Dalton’s Law of Partial Pressure- Many containers do not hold only one kind of gas. The pressure exerted on the side of the container is the sum of the pressure exerted by each of the gases.

DALTON’S LAW OF PARTIAL PRESSURE