Pure and Impure substances and the 3 types of Mixtures

Pure Substances

Pure substances are only made up of one substance. All elements are pure substances.

Heating Pure Substances

Made up of only one element or one compound.
All elements are pure because they each have only one type of atom.
When we are heating up a pure substance, the tempurature rises but will stop rising when solid reaches the melting point. The temperature will not rise until the whole solid has melted, it will continue to rise after this.Then it will stop rising when you reach the boiling point. When all the liquid becomes gas then the tempurature will continue to rise.

At the melting or boiling point instead of the heat energy increasing the temperature, it gives it to the solid particles to allow them to move further apart.

Impure Substances

Impure substances melt or boil at a range of temperartures because they are made up of different substances, and the temperature will contiue to rise whilst they melt/boil unlike pure substances.

Suspension (water and chalk)

These particles will eventually settle down if you do not mix but leave it. The size of particles in a suspension are usually larger than 1000nm.

Solution (water and sugar)

Solvent+Solute=Solution. The size of particles in a solution are usually less than 1nm.

Colloid (water and milk)

The size is between 1nm and 1000nm. IF you leave it, it will NOT settle, it will stay mixed and you will always see the Tyndal effect.

Units

1m = 1000mm

1mm = 1000 μm (micrometres)

1 μm = 1000 nm (nanometres)