MIXTURES, SOLUTIONS AND PURE SUBSTANCES

Matter and its appearance

According to its appearance, there are two kinds of material systems:

Homogeneous systems: they have the same properties and compositions in all different parts of them.

Heterogeneous systems: different parts with different properties can be found in them.

Homogeneous Systems

Heterogeneous Systems

Heterogeneous Mixtures Systems with several different

substances that can be distinguished:

Oil and water. Granite is a rock that has three

different substances: quartz, mica and felspar.

Blood: using a microscope we can see a liquid (plasma) and different kinds of cells.

Smoke: has solid particles in a gas (air).

Heterogeneous Mixtures

How to separate their components:

– If the components are a solid and a liquid, we can separate them by filtering.• E. g.: water and

sand

Heterogeneous Mixtures

How to separate their components:

– Decantation: This method uses the different densities of the components to separate them:• (E.g.: oil and water)

Homogeneous Systems

There are two kinds of homogeneous systems:

Pure substances:

• They have only one component• They have constant

composition and properties. Solutions:

• They have several components.• Their composition can be

changed

Solutions A solution has, at least, two components:

Solute: It is the component that is present in a lower

quantity in the solution. Solvent:

It is the component that is present in excess. Its state never changes when the solution is being

formed

A simple sample: salty water: There is much more water than salt Water is a liquid and the solution too.

SOLUTE = SALT and SOLVENT = WATER

SolutionsThey are not always liquids !!!

Solutions

How to separate its components:

– Evaporation and crystallization: a liquid evaporates at room temperature, but a solid doesn't.

Solutions How to separate its components:

– Distillation: this method is useful to separate:• Liquids whose boiling points are different

• Liquids and solids

Pure SubstancesPure Substances

Pure substances: They have a constant composition. They can't be separated in simpler

substances using physical methods. There are two different kinds of pure

substances: Chemical compounds: pure substances

that cannot be separated using chemical methods.

Elements: pure substances that can't be separated into others

Four kinds of matterFour kinds of matter