Topic 3 - Particle Model of Matter

• Density is the amount of mass per unit volume.
• • in a solid - particles are tightly packed in a regular structure
  • in a liquid - particles are tightly packed but free to move past each other
  • in a gas - particles are spread out and move randomly
• If the object has an irregular shape, the volume can be measured using a displacement can.
• Method 1: Regular solids


  1. Use a ruler to measure the length (l), width (w) and height (h) of a steel cube

  2. Place the steel cube on the top pan balance and measure its mass

  3. Calculate the volume of the cube using (l × w × h)

  4. Use the measurements to calculate the density of the metal

  5. Use vernier callipers to measure the diameter of the sphere

  6. Place the metal sphere on the top pan balance and measure its mass

  7. Calculate the volume of the sphere using (4/3) π (d/2)^3

  8. Use the measurements to calculate the density of the metal
• Method 2: Stone or other irregular shaped object


  1. Place the stone on the top pan balance and measure its mass

  2. Fill the displacement can until the water is level with the bottom of the pipe

  3. Place a measuring cylinder under the pipe ready to collect the displaced water

  4. Carefully drop the stone into the can and wait until no more water runs into the cylinder

  5. Measure the volume of the displaced water

  6. Use the measurements to calculate the density of the stone
• Method 3: Water (or any liquid)


  1. Place the measuring cylinder on the top pan balance and measure its mass

  2. Pour 50 cm3 of water into the measuring cylinder and measure its new mass

  3. Subtract the mass in step 1 from the mass in step 2. This is the mass of 50 cm3 of water

  4. Use the measurements to calculate the density of the water
• Density

  Mass ÷ Volume
• The internal energy is the total amount of kinetic energy and chemical potential energy of all the particles in the system.
• Change in state

  A) Melting

  B) Freezing

  C) Evaporation

  D) Condensation

  E) internal energy

  
• Determining the specific heat capacity of vegetable oil


  1. Place beaker on balance and zero it

  2. Add oil and record mass

  3. Place thermometer and immersion heater in oil

  4. Insulate beaker with foam

  5. Connect joulemeter to immersion heater

  6. Leave setup for 30 minutes

  7. Record total joules of energy and final temperature
• Specific heat capacity


  The amount of energy required to raise the temperature of one kilogram of a substance by one degree Celsius
• Specific heat capacity = Change in thermal energy / (Mass x Temperature change)
• Potential sources of inaccuracy

  • Thermal energy passing to beaker and air
  • Not all thermal energy from heater passes to oil
  • Incorrectly reading thermometer
  • Thermal energy not spreading evenly through oil
• Specific latent heat is the amount of energy required to change the state of 1 kilogram (kg) of a material without changing its temperature.
• • latent heat of fusion - the amount of energy needed to melt orfreeze the material at its melting point
  • latent heat of vaporisation - the amount of energy needed to boil or condense the material at its boiling point
• Specific Latent Heat

  A) Melting

  B) Boiling

  C) Solid

  D) Liquid

  E) Gas

  
• Gas Pressure

  Since the particles in a gas are moving fast and randomly, collisions occur frequently. These collisions may be between two particles, between a particle and the wall of the container, or between a particle and something else in the container.
• As the temperature increases, the pressure increases showing that pressure is directly proportional to temperature.
• Boyle was able to show that volume is inversely proportional to pressure.
• Mechanical work transfers energy from the person or machine’s store of chemical energy to the internal energy store of the gas.