Chemistry - Filtration terms

Criteria of purity

This refers to all those physical properties which are characteristic of a pure substance.

Separation techniques

Separation techniques are methods used to obtain pure substances from their mixtures

Mixture

It is a substance which consists of two or elements which are physically combined but not chemically combined.

Solution

It is a mixture made up of a solvent and a solute.

Solvent:

It is a liquid in which a solute dissolves.

Solute

It is a substance that dissolves in a solvent. A solute can either be a solid, liquid or gas.

Miscible liquids

They are liquids that can mix completely

Immiscible liquids

They are liquids that do not mix completely

Residue

It is a solid that is trapped on the filter paper during filtration.

Filtrate

It is a clear liquid collected after filtration

Filtration

This is a method of separating an insoluble solid from a liquid using a filter.

Application of filtration

(a) It is used in the purification of drinking water at the water works.

(b) It is used in car engines to remove impurities from oil, petrol etc.

Distillation

It is a process of vapourizing a liquid and then condensing the vapour.

Simple distillation

It is a process used to separate a pure liquid from a solution containing dissolved solids

Fractional distillation

It is process of separating a mixture of two or more miscible liquids which have different boiling points.

Distillate

It is a pure and condensed liquid obtained by distillation.

Industrial application of fractional distillation

(a) Separation of various components of crude oil (petroleum)

(b) Used in the manufacture of spirits such as whisky, rum, gin etc.

(c) Separation of liquid air into nitrogen and oxygen

Separating funnel

The separating funnel is used to separate two or more immiscible liquids e.g. a mixture of water and oil.

Decantation

Decantation is the process of separating by carefully pouring a solution from a container in order to leave the precipitate (solid particles) at the bottom.