Chem 1035 Chapter 5 1 of 32 Chapter 5 Gases and the Kinetic-molecular Theory Three Phases of Matter: Gas Liquid Solid -particles are far apart. A gas is mostly empty space. -gases are compressible -particles are closer together. -liquids are not compressible -particles are very close together in a regular, repeating pattern. -solids are not compressible -gas particles are very mobile with high velocities (~ 1mi/s) -particles are in constant motion, moving randomly and freely liquid particles move with less freedom of motion -particles are not mobile but can only move in place. The particles are held in place. Chem 1035 Chapter 5 2 of 32 Gas Liquid Solid -there are negligible attractive forces between gas particles so they are free to move. -gases take the shape and volume of their container -there are moderately strong attractive forces holding particles close to each other. -liquids take the shape but not the volume of their container -there are strong attractive forces holding solid particles rigidly in place. -solids do not take the shape or volume of their container Chem 1035 Chapter 5 3 of 32 Kinetic Molecular Theory of Gases Chem 1035 Chapter 5 4 of 32 Gases consist of particles, which have the following properties: The particles are so small compared to the distances between them that the volume of the individual gas particles can be assume to be negligible (zero). The particles are in common motion. The collisions of the particles with the walls of the container are the cause of the pressure exerted by the gas. The particles are assumed to exert no forces on each other; they are assumed to neither attract nor repel each other.