Chemistry

• Change of state:

  • Speed of particle doesn't change so kinetic energy doesn't change
  • Temperature will remain the same as kinetic energy is constant
  • Additional energy used to change potential energy
  • Potential energy changed then forces also change
  • Particles move further apart,forces decreased (Potential energy increases)
  • Closer together ,forces strengthen (Potential energy decreases)
• When the particles move further apart


  Potential energy increases
• When the particles move closer together


  Potential energy decreases
• Explanation of graph

  1. A-B: Ice molecules (solid) absorb energy without melting

  2. Temperature increases

  3. Vibration of particles increases in intensity

  4. Average kinetic energy of particles increases
• Explanation of graph

  1. B-C: Ice begins to melt

  2. Temperature remains the same while melting, until all the ice has melted

  3. Movement of particles stays the same

  4. Potential energy increases
• Explanation of graph

  1. C-D: Water molecules (liquid) absorb energy without boiling

  2. Temperature increases

  3. Particles move faster

  4. Average kinetic energy of particles increases
• Explanation of graph

  1. D-E: Water boils

  2. Temperature remains the same while boiling, until all the water becomes vapour

  3. Movement of particles stays the same

  4. Potential energy increases
• Explanation of graph

  1. E-F: Vapour molecules absorb energy

  2. Temperature increases

  3. Particles move faster

  4. Average kinetic energy of particles increases
• • If temperature is less than melting point , substance is solid
  • If temperature is between melting and boiling point the substance is liquid
  • If temperature is higher then boiling point then substance is gas
• Kinetic molecular theory

  Theory used to explain the behaviour of the particles in all three states of matter
• Kinetic molecular model

  • All matter is composed of tiny particles
  • The particles are in constant motion
  • There are empty spaces between the particles
  • Forces of attraction and repulsion exist between the particles
  • The particles are continuously colliding with one another and the sides of the container. These collisions are all elastic (no kinetic energy is lost during the collisions)
  • At any given time, the speed and kinetic energy of the individual particles will differ, but the average kinetic energy of all the particles will remain constant if the temperature remains constant
  • A state change may occur when the energy of the particles change
• Properties of the different states of matter according to the kinetic theory

  • Solid: Consists of small particles, only vibrate, very small spaces between the particles, this explains why solids cannot be compressed
  • Liquid: Consists of small particles, move randomly but restricted, spaces slightly larger than in solids, this explains why liquids can be compressed slightly
  • Gas: Consists of small particles, move freely, large spaces between the particles, this explains why gases can be compressed
• Solid compression


  Cannot be compressed easily due to the small spaces between the particles
• Liquid compression


  Can be compressed slightly due to the slightly larger spaces between the particles
• Gas compression


  Can be compressed easily due to the large spaces between the particles