Topic 14-particle model

• Density(kg/m^3)= mass(kg)/volume(m^3)
• What does density depend on

  how close its particles are to each other.
• Why does solid have highest density ?


  particles are very close together and the forces of attraction between them are strong.
• The kinetic theory model shows how particles are arranged in each state of matter.
• density: 1g/cm^2 = 1000kg/m^3 (waters density)
• What is specific heat capacity?

  Amount of energy it takes to raise tempature of 1kg of that substance by 1°c
• What is water specific heat capacity

  4200J/kg°C
• What is specific heat capacity measured in?

  J/kg°C
• Change in thermal energy = mass × specific heat capacity × change in tempature
• What is latent heat?

  Energy needed for substance to change state
• When substance changes state

  The energy supplied increase internal energy stored but not change temperature of substance
• What is specific latent heat?

  Energy required to change state of 1kg of substance with no change in temperature
• Thermal energy for change of state(J) = mass(Kg) × specific latent heat (J/kg)
• What is thermal insulation for?

  Reduced unwanted energy transfers
• Reduced unwanted energy transfer

  • Air gaps
  • Loft insulation
  • Double glazing of windows
• What is used to miniseries energy transfers

  Materials that are poor conductors
• Why do some systems need more energy than others to warm up?

  Made of different substances
• Why are changes of state physical changes?

  Changes are reversible
• What is tempature of gas proportional to?

  Kinetic energy of particles
• Average kinetic energy of particles is directly proportional to tempature of gas in kelvin
• Tempature in kelvin = tempature in celsius + 273
• What is absolute 0?

  Lowest tempature particles have motion
• Absolute 0 = -273
• What is waters density

  1000kg/m^4
• why should you use foam as a thermal insulator?

  reduces amount of energy lost as it is poor thermal conductor
• pressure produces force at right angle to any surface
• how to calculate pressure?

  force/area
• how does temp increase pressure?

  1. more energy given to particles
  2. thermal energy is transferred to kinetic so particles move at faster speed
  3. collide more often and particles hit wall with greater impact
• The temperature of a gas is proportional to the kinetic energy of its particles.
• when do gas exert pressure?

  when gas particles collide with something
• Why If the volume of a fixed mass of gas is kept constant, increasing the temperature will increase the pressure exerted?

   because particles move faster and collide with the walls of the container more often.
• The pressure exerted by the gas is directly proportional to the temperature of the gas at constant volume.
• temperature in Celsius = kelvin -273
• Changes of state are physical changes, What does this mean?

  they are reversible.
• When substances change state, mass is conserved.

  the mass of a substance before a state change is equal to the mass after the state change.
• what affects the objects thermal energy

  • temperature
  • mass
  • material its made from