AP Chemistry – Kinetic Molecular Theory Kinetic Molecular Theory - Mathematical model that explains the macroscopic behavior of gases. Assumptions: 1. Particle size – gas molecules so small compared to space between them that the volume of partices is assumed to be zero. 2. Particle interaction – gas molecules exert no forces on each other. 3. Particle motion – Straight line motion, collisions are elastic When solving problems using the KMT equations: 1. 2. 3. 4. R will be 8.31 J/mol.K ( J = kgm2/s2, thus 8.31 kgm2/s2molK) Masses (m) must be in kg Mw will be in kg/mol u (avg speed) will be in m/s Examples: 1) Find the average speed of a nitrogen molecule in air at room temperature (25oC). 2) At what temperature would an oxygen molecule have the same velocity as that of SO2 at 300. K? 3) The temperature of the CO2 atmosphere near the surface of Venus is 475 oC. Calculate the avg KE per mole of CO2 molecules on Venus.