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States of Matter. Chapter 13. Kinetic Theory . Kinetic energy is energy due to motion. According to the kinetic theory, all matter consist of particles in constant motion. Three Assumptions of the Kinetic Theory.
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States of Matter Chapter 13
Kinetic Theory Kinetic energy is energy due to motion. According to the kinetic theory, all matter consist of particles in constant motion
Three Assumptions of the Kinetic Theory • The particles in a gas are considered to be hard small spheres with insignificant volume • No attractive or repulsive forces exist • Independent motion • Rapid, constant, random motion • Gases fill their containers • They travel in straight-line paths • The collisions are perfectly elastic • Energy Transferred without loss • Total energy remains the same
Gas Pressure Results from the force exerted by a gas per unit of surface area Gas pressure is the result of simultaneous collisions of rapidly moving particles If no particles, then no collisions, so no pressure
Gas Pressure Atmospheric Pressure results from collisions of atoms in the air with objects Decreases as elevation increases. Ex. Climbing a mountain A barometer measure atmospheric pressure
Units for Pressure SI unit is Pascal (Pa) (this in now a base unit) Standard Units 1 atm = 760 mm Hg = 101.3 kPa = 760 torr = 1 N/m2 = 14.7 psi Have to convert between these units of pressure
Conversions A pressure gauge records 460 kPa. What is the pressure in mmHg? Practice Time!
Kinetic Energy and Temperature Potential Energy = stored energy As temperature increases, kinetic energy increases As a substance cools, kinetic energy decreases
Kelvin SI unit The Kelvin temperature scale reflects the relationship between temperature and average kinetic energy Based on absolute zero of O K – the point at which all motion ceases
States of Matter Solid Liquid Definite volume Definite shape Particles close together Vibrate Definite Volume No definite shape Particles further apart than solid Flow
State of Matter Gas Plasma No definite volume or shape Far apart as possible Gas-like substance Very high temperatures Above 5000C Charged particle Ex. The sun
Changes in States of Matter (Phase Changes) Melting Freezing Solid to liquid Increase in Kinetic energy Liquid to Solid Decrease in kinetic energy
Changes in State Sublimation Deposition Solid directly to a gas Kinetic Energy Increases Ex. Iodine, dry ice, moth balls Gas directly to a solid Kinetic Energy Decreases
Changes in State Vaporization Condensation Liquid to Gas KE increases Gas to Liquid KE decreases
Review Kinetic Energy Increases solid liquid gas Kinetic Energy Decreases Gas liquid Solid
Two Types of Vaporization • Evaporation – changes liquid to gases below boiling point • Cooling process • Boiling Point – when heated to a temperature in which particles have enough Kinetic Energy to vaporize
Terms Normal Boiling Point – the boiling temperature of a substance at standard pressure Vapor Pressure – measure of the force exerted by a gas above a liquid
Phase Diagrams Shows the relationship among solid, liquid, and vapor of a substance Gives the conditions (temperature and pressure) at which a substance exist as a solid, liquid or vapor