properties of matter

• what is the temperature of a substance a measure of?

  the average kinetic energies of the particles in the substance
• what happens when particles in a substance are heated?

  - they gain kinetic energy

  - the temperature of the substance increases
• specific heat capacity

  the energy required (Eh) required to increase the temperature (∆T) of a mass (m) of 1 kg of a material by 1°C
• what factors determine how the temperature of a material changes when heat energy is added or removed?

  - the type of material (specifically its specific heat capacity)

  - the mass of the material
• what happens to heat energy in an open system during energy transfer?

  heat energy is lost to the surroundings
• what is the temperature of a substance when changing state?

  there is no change in temperature
• specific latent heat

  the heat required (or lost) to change state without change in temperature
• specific latent heat of fusion

  the heat energy required to change 1kg of a solid to liquid without a change in temperature
• specific latent heat of vaporisation

  the heat energy required to change 1kg of a liquid to gas without a change in temperature
• temperature-time graphs

  can be used to calculate the specific heat capacity or specific latent heat of a substance (if the mass of the substance and the power rating of the heater used to heat the substance are known)
• pressure

  the force per unit area
• what is the kinetic model of gases?

  the kinetic model states that the particles of a gas are in constant motion, colliding with each other and with the walls of the container they are in
• using the kinetic model, explain why decreasing the volume that a gas occupies increases its pressure

  - when volume decreases, the particles of the gas collide with the container walls more frequently

  - this results in a greater force being exerted on a smaller area

  - as p=F/A, the pressure of the gas increases
• absolute zero

  - the temperature at which no more energy can be removed from matter

  - represents the lowest temperature

  - 0k = -273°C
• using the kinetic model, explain why increasing the temperature of a gas increases its pressure

  - when temperature increases, the particles of the gas gain kinetic energy and collide with the container walls more frequently, at a greater speed

  - this results in a greater force being exerted on the container walls

  - as p=F/A the pressure of the gas increases
• using the kinetic model, explain why increasing the temperature of a gas increases its volume

  - when temperature increases, the particles of the gas gain kinetic energy and collide with the container walls more frequently, at a greater speed

  - this results in a greater force being exerted on the container walls

  - as p=F/A, the volume of the gas must increase to maintain a constant pressure