The Chemist's tools 9.1.8 - Pure substances and mixtures
Matter: states and properties of matter.
Particle/kinetic theory, diffusion.
Pure and impure substances. Types of mixtures (solutions, oils, alloys, emulsions)
Separation techniques, including filtration, distillation [including crude oil - myp10], chromatography.
Separation techniques circus.
Find examples from everyday life for each of the following types of mixtures:
And suggest which of the techniques learned could be applied to separate each mixture.
Students should research the following terms:
They should describe each type of mixture and give two examples from everyday life.
A colloidal system is one with components of one or two phases gas, liquid or solid. In a relatively straightforward system there are two components, one of which is being dispersed and the other known as the continuous medium.
Colloids bridge the gap between solutions and suspensions.
They represent a type of mixture intermediate between a homogeneous mixture (also called a solution) and a heterogeneous mixture, and have properties that are also intermediate between the two.
The size of dispersed phase particles in a colloid range from one nanometre (1 x 10-9 m) to one micrometre (1 x 10-6 m).
Colloids can be classified according to the phases involved.
Liquid in gas: often known as an aerosol e.g. mist
Gas in liquid: this is a foam e.g. whipped cream
Gas in solid: this is usually known as a solid foam e.g. pumice,
expanded polystyrene foam
Notice that gas in gas is not on the list. This is because all gases are soluble in each other and thoroughly mix to give a homogeneous system.
Adapted from http://www.nuffieldfoundation.org/practical-chemistry/formation-sol