1.1 B Kinetic Theory

GOALS

  • Distinguish between different states of matter ✅

  • Use state symbols (s), (l), (g), and (aq) in chemical equations ✅

  • Names of changes of state should be covered: melting, freezing, vaporization (evaporation and boiling, condensation, sublimation, and deposition ✅

KINETIC THEORY

  • temperature and pressure affect states of matter

  • states of matter depend on the energy of particles

  • state of given temperature and pressure determine strength of inter-particle forces

KINETIC ENERGY EK

  • energy associated with movement/motion

  • directly related to temperature - the measure of EK of particles in a substance

Consider the following when describing states of matter

  1. Packing

  2. Inter-Particle forces

  3. Particle motion

  4. Shape

  5. Volume

  6. Compressibility

FLUIDS

  • liquids and gases called fluids - refers to flow ability

DIFFUSION

  • movement of a substance from an area of high concentration to low concentration

  • process; particles of substance become more easily distributed - caused by random movement

  • NOTE: due to Ek = ½mv2 , substances with lower mass diffuse faster (inverse relation between mass and velocity)

CHANGES IN STATE

  • Ek increases with temp

  • as particles move faster, they overcome inter-particle forces and change state

    • occur at fixed temp + pressure for each substance

NOTE: if confused between sublimation and deposition - Sublimation = Solid → gas

EXAMPLES OF SUBLIMATION & DEPOSITION

  • Sublimation - dry ice

  • Deposition - frosting on windshield

VAPORIZATION

  • state change from liquid to gas

  • two kinds - evaporation + boiling

EVAPORATION

  • surface particles acquire heat from the atmosphere

  • when enough kinetic energy is acquired, surface particles become gas

  • occurs below boiling point (temp)

BOILING

  • throughout liquid - characterized by particles leaving throughout liquid (bubbles)

  • Boiling point - when all particles in liquid have enough Ek to become gas

VAPOR PRESSURE

  • pressure exerted by liquid on walls of container

    • evaporation slow; vapor pressure < atmospheric pressure

    • Boiling fast; vapor pressure >/= atmospheric pressure

QUESTIONS - p 11 # 6,7