Physics AQA Topic 3 (Changes of state and particle model)

4.3.1

What is the definition of density

The mass per unit volume of a material

What is the equation for density

ρ = m/v (Density = mass/volume)

What are the units for the equation for density

Density = kilograms per metre cubed (kg/m^3), mass = kilograms (kg), volume = metres cubed (m^3)

State the different states of matter in order of density of atoms (least to most)

Gas, liquid, solid

Describe the particle arrangement of a solid

Tightly packed in a regular arrangement and particles can only vibrate on the spot - most particles (so largest mass) per unit volume - most dense

Describe the particle arrangement of a liquid

Close together but with an irregular arrangement, and particles can flow over each other - fewer particles (so smaller mass) per unit volume - less dense

Describe the particle arrangement of a gas

Separated, with no arrangement, and particles can move freely - least particles (so smallest mass) per unit volume - least dense

What is always conserved when a substance undergoes a change of state

Mass

How does a change of state differ from a chemical change

In a change of state, the material can return to having tis previous properties if the change is reversed unlike in chemical changes

What is sublimation

When a solid changes into a gas without passing through a liquid state

What is evaporation

When a liquid changes into a gas state

What is the opposite of evaporation

Condensation, which is when a gas changes into a liquid state

When water boils in an open pan why does the mass of the pan of water appear to decrease

Some of the water will evaporate and turn into water vapour which will leave the pan, meaning the mass of the pan and the water in it will decrease but the mass of the whole system remains constant

Explain the processes involved when a bathroom mirror mists up

Hot water evaporates to form water vapour which lands on the cool mirror, condensing and returning to liquid state on the mirror's surface