P3 Particle Model of Matter

Describe solids

Strong force bond, close together, regular arrangement, vibrate, fixed positions

Describe liquids

Particles in contact, weak force of attraction, move freely and randomly

Describe gases

Particles widely spaced, no forces between particles, move quickly with random motions, range of speeds

What is evaporation:

Happens at the surface of a liquid at temperatures below its boiling point. Rate of evaporation increases with temperature.

What is boiling?

At the boiling point, bubbles of vapour form inside the liquid and rise to the surface.

Increasing temperature increases pressure because:

• average kinetic energy of gas molecules increases

• The gas molecules travel faster so they hit the container surfaces with more force and more frequently

• Pressure is proportional to temperature

Increasing volume decreases pressure because:

• distance (and therefore time) between collisions is increased, so number of collisions per second is reduced

• Pressure is inversely proportional to volume

What is latent heat?

The energy transferred to or from a substance during a change of state

What is internal energy?

The total energy stored by the particles of a substance

How do you measure specific heat capacity?

1) set up practical like diagram

2) measure energy transferred to metal block

3) record start and end temperature and work out temperature change

4) use top pan balance to find mass of block

5) Use equation to calculate specific heat capacity

What is specific latent heat of fusion?

Energy needed to change 1kg of substance from solid to liquid

What is specific latent heat of vapourisation?

Energy required to change 1kg of substance from liquid to gas