Diffusion & Dilution (Edexcel IGCSE Science (Double Award))

Diffusion and dilution

• Diffusion and dilution experiments support a theory that all matter (solids, liquids and gases) is made up of tiny, moving particles

Diffusion in gases

Diffusion of red-brown bromine gas

Description:

• Here, we see the diffusion of bromine gas from one gas jar to another

• After 5 minutes the bromine gas has diffused from the bottom jar to the top jar

Explanation: 

• The air and bromine particles are moving randomly and there are large gaps between particles

• The particles can therefore easily mix together

Diffusion in liquids

Diffusion of potassium manganate(VII) in water over time

Description:

• When potassium manganate (VII) crystals are dissolved in water, a purple solution is formed

• A small number of crystals produce a highly intense colour

Explanation: 

• The water and potassium manganate (VII) particles are moving randomly and the particles can slide over each other

• The particles can therefore easily mix together

• Diffusion in liquids is slower than in gases because the particles in a liquid are closely packed together and move more slowly

Dilution

Dissolving potassium manganate (VII) in water

Description:

• When potassium magnate (VII) crystals are dissolved in water, the solution can be diluted several times

• The colour fades but does not disappear until a lot of dilutions have been done

Explanation:

• This indicates that there are a lot of particles in a small amount of potassium manganate (VII) and therefore the particles must be very small