Particle model of matter P1

• How do you fine the density of a solid (irregular) object?

  1. Using a balance measure its mass
  2. Submerge object in water in a eureka can filled with water.
  3. Water displaced by the object will be caught in a beaker and transferred to a measuring cylinder
  4. Record the volume of water in the cylinder
  5. Then use the formula Density= mass/volume
• What are the properties of a solid?

  -Strong forces of attraction, which hold particles together in a fixed position

  -Regular arrangement

  -Not much energy particles only vibrate

  -Highest density
• What are the properties of a liquid?

  -Weaker forces of attraction

  -More energy than solids

  -Irregular form

  -Less dense than solids
• What are the properties of gas?

  -No forces of attraction

  -Particles have more energy than solids and liquids

  -Free to move- random direction

  -Low density
• Why do particles in a system vibrate or move around?

  They have energy in their kinetic energy stores
• What is internal energy?

  Total energy that its particles have in their kinetic and potential energy stores
• How does a change in state occur?

  If the particles are heated enough they will have enough energy in their kinetic stores to break the bonds holding them together
• How can a state change due to cooling?

  The particles loose energy and form bonds
• Does change in state affect mass?

  No, the number of particles dont change- they're just arranged differently. Therefore mass is conserved.
• What is specific latent heat?

  The amount of energy needed to change 1kg of a substance from one state to another without changing its temperature
• When a substance is melting or boiling, what is the energy used for?

  Breaking bonds between particle- not raising the temprature.
• What happens when a substance is condensing or freezing?

  Bonds are forming between particles, which releases energy. This means internal energy decreases.
• What is specific latent heat for changing between a solid and a liquid called?

  Specific latent heat of fusion
• What is specific latent heat for changing between a liquid and a gas called?


  Specific latent heat of vaporisation
• Formula for specific latent heat

  
• What happens if you increase the temperature of a gas?

  The average speed of its particles increases
• Pressure and volume are inversely proportional
• What happens when you do work (transfer energy by applying force)on a gas?

  Increases internal energy which can increase temp
• What factor affects the average kinetic energy of gas molecules?

  ● The temperature of the substance

  ● The higher the temperature, the higher the average kinetic energy of the molecules
• What effect does increasing temperature have in the pressure of a gas when help at a constant volume?

  Pressure of the gas will increase as the temperature increase
• Why does pressure increase as temperature increases (at a constant volume)?

  ● Kinetic energy of molecules increases

  ● Collisions between molecules becomes more frequent

  ● Greater rate of change of momentum

  ● Greater force and therefore pressure
• If gas A is at a low pressure, and gas B is at a high pressure, what can be said about the rate of collisions in each gas?


  ● There are more collisions per second in gas B than in gas A

  ● The rate of collisions is higher in B
• Describe the force that the pressure of a gas exerts on the walls of its container.

  ● The net force acts at right-angles to the container’s surface

  ● The force increases as pressure increases
• Explain how increasing the volume of a gas results in a decrease of pressure.

  ● Molecules become more spread out and so time between collisions increases

  ● This reduces the rate of collisions

  ● Rate of change of momentum decreases, and so force exerted on container decreases, resulting in a lower pressure
• What can be said about the product of pressure and volume for a fixed mass of gas at a constant temperature?

  It is constant.

  p V = constant
• What increases when you do work on a gas?

  ● The internal energy of the gas

  ● This can also lead to an increase of temperature
• Why does the temperature of air inside a bike pump increase when it is pumped?

  ● Work is done on a gas when it is compressed

  ● Doing work on a gas increases its internal energy, so also increases the average kinetic energy of the molecules

  ● Temperature increases with an increase o