Mixtures

A mixture is made from different substances that are not chemically joined.

For example powdered iron and powdered sulphur mixed together makes a mixture of iron and sulphur. They can be separated from each other without a chemical reaction, in the way that different coloured sweets can be picked out from a mixed packet and put into separate piles.

Separation of liquids

Liquids can be described in two ways – immiscible and miscible. The separation technique used for each liquid depends on the properties of the liquids. Immiscible liquids are liquids which do not mix together and form separate layers, E.g. Oil and water OR lava lamps (Molten plastic and water)

Miscible liquids do mix well together and will not form separate layers, E.g. Petrol and diesel.

Immiscible liquids

Immiscible means that the liquids don't dissolve in each other – oil and water are an example. It is possible to shake up the liquids and get them to mix but they soon separate. Separating immiscible liquids is done simply using a separating funnel. The two liquids are put into the funnel and are left for a short time to settle out and form two layers. The tap of the funnel is opened and the bottom liquid is allowed to run. The two liquids are now separate.