P3 - Particle Model of Matter

• Density


  The mass per unit volume of a material
• Calculating density


  mass / volume
• Density (ρ)


  Measured in kilograms per metre cubed (kg/m³)
• Mass (m)


  Measured in kilograms (kg)
• Volume (V)


  Measured in metres cubed (m³)
• State of matter

  The structure and form of a substance, i.e. gas, liquid or solid
• Incompressible

  Cannot be compressed / squeezed / compacted
• Particle

  An extremely small body with finite mass and negligible (insignificant) size, e.g. protons, neutrons and electrons
• Density


  A measure of mass per unit of volume, measured in kilograms per metre cubed (kg/m³)
• Meniscus


  The curved upper surface of a liquid standing in a tube, from which measurements of volume are taken
• Latent heat of fusion


  The amount of heat energy needed for a specific amount of substance to change from solid to liquid
• Latent heat of vaporisation


  The amount of heat energy needed for a specific amount of substance to change from liquid to gas
• Sublimation


  The process of changing state directly from a solid to a gas without first melting
• Change of state

  1. As energy is added to a system, its temperature will increase

  2. At the melting or boiling point, the energy being added causes the substance to change state, not temperature

  3. A change of state is reversible. It is a physical change that alters the internal energy but not the temperature or mass. It is not a chemical change
• Density Required Practical:

  1. Half-fill a measuring cylinder with water and measure the volume of the water
  2. Measure the mass of the solid/liquid being tested
  3. Add the solid/liquid being tested to the cylinder
  4. Record the new volume of the water
  5. Subtract the original volume from the new to give the volume of the solid/liquid being tested
  6. Calculate the density
• Density Required Practical:

  •Independent Variable - material being tested

  •Dependent Variable - Volume and mass

  •Control Variable - Temperature
• Energy for a change of state = mass × specific latent heat
• Specific Latent Heat is the energy needed to change state
• Energy (J) = Mass (kg) x Specific Heat Capacity (J/kg°C)