LSS Kinetic Particle Theory

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Kinetic Particle Theory

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LSS Kinetic Particle Theory

  1. 1. Kinetic Particle Theory
  2. 2. Learning Outcomes • At the end of the lesson, the students should be able to: – 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
  3. 3. States of Matter • Matter can exist as a solid, a liquid or a gas. • Kinetic particle theory states that – all matter is made up of tiny particles and – that these particles are in constant random motion.
  4. 4. Comparing the 3 states Property Solid Liquid Gas Shape Fixed Not fixed Not fixed Volume Fixed Fixed Not fixed Cannot be compressed Cannot be compressed Can be compressed Strong Weaker than that in solid weak Compressibility Forces of attraction between particles
  5. 5. Comparing the 3 states Property Solid Liquid Gas Arrangement of particles closely packed in orderly manner closely packed in random order far apart
  6. 6. Comparing the 3 states Property Movement of particles Solid Liquid cannot move, free to move vibrates and within the rotates about liquid, their fixed vibrates and position slides over one another Gas free to move, move rapidly in any direction
  7. 7. Changes in States of Matter • The physical state of a substance depends on the temperature and pressure of the surroundings. • For example – At room temperature (25 oC), water is in the liquid state. – At -10 oC, water is in the solid state.
  8. 8. Changes in State • Heat is a form of energy. • When matter is heated, the particles absorb energy. • When matter is cooled, the particles lose energy. • the heat taken in or given out causes the kinetic energy of the particles to change. • Hence, the substance changes it state.
  9. 9. Changes in States of Matter condense melt boil condense freeze sublime
  10. 10. Changes in States of Matter Melting Physical change Energy change Boiling Freezing Condensation Sublimation Solid to liquid liquid to gas liquid to solid gas to liquid solid to gas Energy Energy Energy Energy Energy absorbed absorbed given out given out absorbed
  11. 11. Changes in States of Matter • What happens during melting – particles gain energy, – particles vibrate faster, – particles overcome attractive forces between them, – particles break away from their fixed positions
  12. 12. Changes in States of Matter • What happens during boiling – particles gain kinetic energy, – particles move faster, – particles overcome forces holding them together, – particles spread far apart, – particles move rapidly in all directions
  13. 13. Changes in States of Matter • What happens during freezing – particles lose kinetic energy, – particles move more slowly until they no longer have enough energy to move about freely, – particles settle into fixed position
  14. 14. Changes in States of Matter • What happens during condensation – particles lose energy, – particles move more slowly, – becomes a liquid
  15. 15. Sublimation • Particles at the surface of the solid have enough energy to break away from the solid and escape as a gas
  16. 16. Changes in States of Matter Melting Temp at which change occurs Boiling melting point boiling point Freezing Condensation Freezing point -
  17. 17. Wake Up Call 1 1. When water vapour condenses to water, the particles in the vapour A gains energy. B decrease in density C move closer to each other D mover further apart from each other. Answer: C
  18. 18. Wake Up Call 1 1. Three substances have the following properties: X: melts at -180 oC and boils at -167 oC Y: has shiny crystalline surface at r.t.p Z: can flow and take the shape of container at rtp; has boiling point of 160 oC What is the state of each substance at room temperature and pressure? X Y Z A Gas Solid Liquid B Gas Liquid Liquid C Liquid Solid Solid D Gas Liquid Solid Answer: A
  19. 19. Wake Up Call 1 3 (a) For the following substances state the physical state (solid, liquid or gaseous) they are in at a temperature of 1500 oC. Substance Melting Point / oC Boiling Point / oC Copper 1084 2562 Calcium 842 1484 Iron 1538 3134 Gold 1064 2856 Physical State
  20. 20. Wake Up Call 1 b) Hence draw and describe the arrangement and movement of particles of copper, calcium and iron at the temperature of 1000 oC. (i) Copper Arrangement: – closely packed in orderly manner Movement: – cannot move, vibrates and rotates about their fixed position (ii) Calcium Arrangement – closely packed in random order Movement – free to move within the liquid, vibrates and slides over one another
  21. 21. Temperature Changes • When matter is heated energy causes temperature to increase. • Temperature stops increasing at melting / boiling points. • Particles absorb the heat energy to vibrate faster and move further apart. • Matter changes state. Figure showing the heating curve of water

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