Movement of particles

What is diffusion?

The movement of particles through a liquid or gas from an area of high concentration to an area of low concentration

Name three experiments used to demonstrate diffusion:

• Potassium Manganate (VII) and water

• Ammonia and Hydrogen Chloride

• Bromine Gas and Air

Describe the Potassium Manganate (VII) and water test to demonstrate diffusion

Potassium Manganate (VII) is bright purple

Take a beaker of water + potassium Manganate (VII) to the bottom → purple colour slowly spread out to fill beaker

Particles of potassium Manganate (VII) are diffusing out amount particles of water

Random motion of particles in liquid cause purple colour to eventually be evenly spread out

What happens when you add more water to potassium Manganate (VII) + water

Potassium Manganate (VII) particles spread out even further → less purple = dilution

Describe the ammonium and hydrogen chloride test to show diffusion

Aqueous ammonia (NH3) gives off ammonia gas. (HCl) gives off hydrogen chloride gas.

Each gas diffuses from a different end of the tube, when they meet white ring of ammonium chloride forms

Ring dosent form in middle - forms closer to end where hydrochloric acid was

This shows that ammonia diffuses faster as it travels further in the same amount of time

Ammonia gas diffuses faster → particles of ammonia are smaller + lighter than the particles of hydrogen, so they infuse through the air more quickly

Describe the bromine gas and air test to demonstrate diffusion

Bromine gas - brown, strongly smelling - use to demonstrate diffusion in gases

Fill half a gas jar full of bromine gas - other half full of air, separate gases with glass plate

When you remove plate - see brown bromine gas slowly diffusing through air

Random motion of particles means bromine will eventually diffuse right through the air

What is a solution?

A mixture of a solvent and solute that does not separate out

How is a solution formed?

When you add a solid (the solute) to a liquid (the solvent) the bonds holding the solute molecules together sometimes break and the molecules then mix with the molecules in the liquid - forming a solution. This is called dissolving.

What is a solute?

the substance being dissolved

What is a solvent?

The liquid the solute is dissolving into

What is a saturated solution?

A solution, where the maximum amount of solute has been dissolved, so no more solute will dissolve in the solution