Topic 14 Particle Model

• What is the formula for density?


  $\rho =$$\frac{m}{V}$
• What are the units of density?

  kgm⁻³
• How does density depend on the spacing of atoms in matter?

  Density is influenced by how closely packed the atoms are in a substance.
• How do the densities of solids, liquids, and gases compare?

  • Solids and liquids have similar densities due to minimal spacing changes.
  • Liquids usually have lower density than solids, except for ice and water.
  • Gases have much lower density due to increased spacing between particles.
• What happens to mass during a change of state?

  Mass is conserved during a change of state.
• If 20g of liquid evaporates, how much does the gas produced weigh?

  20g
• Why are changes of state considered physical changes?

  Because the material retains its original properties when reversed.
• What happens to particles when a system is heated?

  • The amount of energy the particles have increases.
  • Particles vibrate more.
  • The temperature of the system increases or the system changes state.
• What are the different changes of state for matter?

  • Melting
  • Freezing
  • Evaporating
  • Condensing
  • Sublimation
• What is specific heat capacity?

  The energy required to raise the temperature of 1kg of a substance by 1°C.
• What is the formula for calculating energy in relation to specific heat capacity?

  $E =$$mc\Delta T$
• What are the units for specific heat capacity?

  Jkg⁻¹°C⁻¹
• What is specific latent heat?

  The energy to change the state of 1kg of a substance without a change in temperature.
• What is the specific latent heat of fusion?

  The energy required to melt or freeze 1kg of a substance.
• What is the specific latent heat of vaporisation?

  The energy required to boil or condense 1kg of a substance.
• When is energy absorbed and released during phase changes?

  Energy is absorbed when melting and evaporating, and released when freezing and condensing.
• What is the formula for calculating energy in relation to specific latent heat?

  $E =$$ml$
• What are the units for specific latent heat?

  Jkg⁻¹
• How can thermal energy loss be reduced in a system?

  • Use thermal insulators like foam.
  • Apply reflective coatings to reflect IR radiation back into the system.
  • Consider the situation to determine insulation methods.
• What is the formula for pressure?

  $pressure =$$\frac{force}{area}$
• How does pressure relate to the movement of gas particles?

  Gas particles move randomly and collide with surfaces, exerting pressure.
• What happens to pressure when the temperature of a gas increases at constant volume?

  Pressure increases as particles move faster and collide more often with walls.
• What is absolute zero in Kelvin and Celsius?

  0 Kelvin or -273°C.
• What occurs at absolute zero?

  Particles have no energy and do not vibrate at all.
• How do you convert Kelvin to Centigrade?

  $T_{kelvin} =$$T_{centigrade} +$$273$
• What happens to the volume of a gas when pressure increases?

  The volume decreases as the gas compresses.
• What is the relationship between pressure and volume for a gas at fixed mass and temperature?

  Pressure is inversely proportional to volume.
• What is the equation relating pressure and volume for a gas?

  $P_1V_1 =$$P_2V_2$
• What happens when work is done on a gas?

  The temperature of the gas increases.
• What is the formula for work done on a gas?

  $W_D =$$F \times d =$$P \times V$
• What happens when more gas is pumped into a fixed volume?

  Pressure increases due to more collisions with the walls.
• What occurs when the volume of a gas decreases with a fixed number of particles?

  Pressure increases as particles collide with the walls more frequently.
• How does the velocity of particles change when they collide with a wall that is moving inward?

  Particles gain momentum and rebound with greater velocity.
• What happens to the temperature of a gas when its pressure increases?

  The temperature increases as the kinetic energy of each particle increases.