Science

24.05.17

Mixtures:
A mixture, from  different substances, not chemically joined.
Concrete for example ( mixture of cement, sand or gravel, and water. Concrete can be altered by substances that make up the mixture.

Separating Mixtures:
There different substances in mixtures are usually easily separated from one another.
Filtration-Separating a Solid mixed with a Liquid.

Solutions:
When salt or sugar 'disappears' into water, we say that the substance has dissolved in the water.
Some substances don't  dissolve (e.g sand will not dissolve in water).

Concentration:
When comparing solutions, it is important to know how much solute has been dissolved in the solvent. Scientists  use the terms dilute and concentrated to describe how 'strong' a solution is.

Saturation:
A solution will become saturated when no more solute will dissolve in the solvent. A solution that is saturated has a high concentration. If some of the solvent evaporates from a saturated solution, solution becomes super saturated and crystals of solute will start to form.

Separating Solutions:
Although a solution is a mixture, the solute cannot be separated from the solvent by filtration. The solute will simply pass through the filter paper.

Distillation- Separating a Solid Dissolved in a liquid:
Evaporation is a simple technique for separating a solid dissolved in a liquid. We need to trap the solvent as it evaporates and condense it back into a liquid. Scientist call this process distillation.

Chromatography: Separating a Mixture of Coloured Compounds:  Chromatography (chroma- Greek for 'colour' and graphy meaning 'words' or 'pictures'. The pigments separate because they have different solubillities  in a solvent. This means that more soluble pigments are carried faster, and therefore further, by the rising solvent.