chem notes

1 Kinetic Particle Theory Learning Outcomes: (a) describe the solid, liquid and gaseous states of matter and explain their interconversion in terms of the kinetic particle theory and of the energy changes involved. (A) The Kinetic Particle Theory states that: a) All matter is made up of tiny discrete particles b) The particles are in constant motion (B) State of Matter Solid Liquid Gas Movement Particles vibrate in fixed position Particles slide over each other. Particles move rapidly and in all direction Arrangement Particles are very closely packed. Particles are arranged in an orderly manner. Particles are closely packed. Particles are not in orderly arrangement. Particles are far apart. Particles are not in orderly arrangement. Energy Energy is low Energy is low Energy is high Forces of attraction strong weak Very weak Diagram (C) Change of State Solid Liquid Gas MELTING endothermic BOILING endothermic FREEZING exothermic CONDENSATION exothermic SUBLIMATION e.g. dry ice, iodine, ammonium chloride endothermic

2 (D) Heating/Cooling Curve MELTING CONDENSATION A – B As the solid is heated, the particles gain kinetic energy and start to vibrate faster. A – B As the gas is cooled, the particles lose kinetic energy and start to move slower. B – C • A mixture of liquid and gas exists here. • When the temperature is low enough, the particles do not have enough energy, particles start to move closer till they are closely packed. C – D The particles become closer and slide over one another. The substance becomes liquid. B – C • A mixture of solid and liquid exists here. • During the melting process, the temperature of the substance remains constant. All the heat energy taken in by the particles is used to overcome the forces of attraction between particles. C – D The particles move freely and slide over one another. The substance becomes liquid. BOILING FREEZING C – D As the liquid is heated, the particles gain kinetic energy and start to move faster. C – D As the liquid is cooled, the particles lose kinetic energy and start to move slower. D – E • A mixture of solid and liquid exists here. • When the temperature is low enough, the particles do not have enough energy, the particles start to move closer till they are held in fixed position. E – F The particles become closer and vibrate about fixed position one another. The substance becomes solid. D – E • A mixture of liquid and gas exists here. • During the melting process, the temperature of the substance remains constant. All the heat energy taken in by the particles is used to overcome the forces of attraction between particles. E – F They spread far apart and move rapidly in all directions. The substance is now a gas. Temperature/ oC Time/min Temperature/ oC Time/min solid Solid + liquid liquid Liquid + gas gas gas Li