Topic 14

• The lowest possible temperature, particles have no kinetic energy and so are completely stationary.

  Absolute Zero
• The product of the mass, specific heat capactiy and temperature change of a substance.

  Change in Thermal Energy
• Changes to the chemical structure of a substance. The substance does not usually restore its original properties when the changes are reversed.

  Chemical Changes
• The mass per unit volume of an object.

  Density
• The temperature of a gas is directly proportional to the average kinetic energy of its molecules.

  Gas Temperature
• The energy stored by the atoms and molecules that make up a system. It is equal tot he sum of the total kinetic and potential energies of the particles in the system.

  Internal Energy
• The SI unit of temperature, based on an absolute temperature scale. To convert from degrees Celsius to degrees Kelvin, subtract 273 degrees.

  Kelvin
• The energy required for a substance to change state.

  Latent Heat
• The unit of pressure, equal to a force of one Newton acting perpendicular to an area of one metre squared.

  Pascals
• Changes to the physical properties of a substance which can be reversed. Changes of state are physical changes since substances can restore their original properties when the changes are reversed.

  Physical Changes
• The perpendicular force per unit area acting on the surfaces of a container as a result of the gas particles colliding with it.

  Pressure of a Gas
• The force acting perpendicular to a surface, per unit area.

  Pressure
• The amount of energy needed to increase the temperature of one kilogram of a given substance by one degree Celsius.

  Specific Heat Capacity
• The amount of energy needed to change the state of one kilogram of a substance from solid state to liquid state, whilst held at constant temperature.

  Specific Latent Heat of Fusion
• The amount of energy needed to change the state of one kilogram of a substance from liquid state to vapour state, whilst held at constant temperature.

  Specific Latent Heat of Vaporisation
• The amount of energy needed to change the state of one kilogram of a substance, whilst held at constant temperature.

  Specific Latent Heat
• The direct changing of a substance from a solid state to a vapour state, without passing through the liquid phase.

  Sublimation
• A measure of the average kinetic energy of the particles in a substance.

  Temperature
• The addition of an insulating material to reduce the heat loss from a system.

  Thermal Insulation