Separate Physics - P3 Particle Model of Matter Flashcards
What equation links density, mass and volume?
Density = mass / volume
⍴ = m / v
What two energy stores make up the internal energy stored by particles?
Kinetic energy and potential energy stores.
Draw a particle model for a liquid.

Name the change of state when a solid turns straight into a gas.
Sublimation
Draw a particle model for a solid.

Draw a particle model for a gas.

Name the changes of state labelled a, b, c and d.

a) Melting
b) Freezing
c) Boiling
d) Condensing
What is specific latent heat of vaporisation?
The energy needed to change the state of a substance between a liquid and gas (boiling or condensing).
Why is there not a temperature rise during a change of state?

- Energy is put into the system.
- The internal energy of the system increases.
- But the energy is used to break bonds rather than raising the temperature of the system.
What is specific heat capacity?
The amount of energy required to raise the temperature of 1 kg of the substance by 1 oC.
What is specific latent heat?
The amount of energy needed to change the state of 1 kg of a substance.
What is the name for the energy stored by particles?
Internal energy
What happens to the internal energy of a system when heated?
- Particles gain energy
- Kinetic energy store of particles increases
- Particles move faster
- Internal energy increases
What happens when you increase the temperature of a gas at constant volume?
- Increases the pressure
- Because the particles move faster
- Increased frequency of collisions of particles with the sides of the container.
What is specific latent heat of fusion?
The energy needed to change the state of a substance between a solid and liquid (melting or freezing).
What are the units for:
a) Mass
b) Volume
c) Density
a) The units for mass are kg
b) The units for volume are m3
c) The units for density are kg/m3
How would you measure the density of a regular object?

- Measure the volume of the object (e.g. for a square, you would measure the length of the sides using a ruler and multiply length x width x height)
- Measure its mass using a balance.
- Calculate density using the equation: density = mass / volume
How would you measure the density of a liquid?
- Use a measuring cylinder to measure the volume of a liquid.
- Use a balance to measure the mass of a liquid.
- Calculate density using the equation: density = mass / volume
What do the horizontal lines on a heating or cooling curve represent?

A change of state
How would you measure the density of an irregular object?
- Measure the mass using a balance.
- Measure volume by placing the object in a eureka can filled with water.
- Measure the volume of water displaced into a measuring cylinder to find the volume of the object.
- Calculate density using the equation: density = mass / volume
Separate Q. What are the SI units for:
a) Pressure
b) Temperature
a) The units for pressure are pascals (Pa)
b) The units for temperature are oC
Separate Q. Describe what causes gas pressure in a sealed container.
- Gas particles collide with the sides of the container.
- With each collision, they exert a force on the container.
- The outward pressure is the total force of all the particles exerted over the area of container walls.
Separate Q. Describe the relationship between pressure and volume.
- Pressure and volume are inversely proportional.
- As volume increases, pressure decreases.
- As volume decreases, pressure increases.
Separate Q. Why does increasing the volume in which a gas is contained, at constant temperature, decrease the pressure?
Increasing the volume spreads the particles out so they hit the container less often, decreasing the pressure.
Separate Higher Q. What effect does ‘doing work’ on a gas cause?
- An increases in internal energy.
- An increase in temperature.
Separate Q. When particles collide with the surface of a container, at what angle is the force exerted?
At right angles to the surface of the container.
Separate Higher Q. Give the definition of ‘work’.
The transfer of energy by a force
Separate Higher Q. Explain why a bike tyre gets warmer as you pump it up.
- The gas particles apply pressure on the pump and therefore exerts a forces against the pump.
- You have to ‘do work’ against the force in order to push down the pump and push air into the tyre.
- By ‘doing work’, you transfer energy to the kinetic energy stores of the gas particles.
- The temperature increases, so the bike tyre will feel warmer.