Compounds, mixtures and seperating mixtures by CGP

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Compounds contain two or more elements joined up

When two or more elements join together, a molecule is made. The join is known as a chemical bond.

Compounds are formed when atoms from different elements join together

An element which is made out of atoms are all the same but not joined up and it is still called an element.

An element which is made out of molecules are joined up but there is still only one type so it is still called an element

Molecules in a compound are where different atoms are joined together and this is called a compound.

A mixture of different elements is not a compound it is just a mixture of different elements.

Compounds are formed from a chemical reaction

A chemical reaction involves chemicals called reactants combining together or splitting apart to form one or more new substances called the products

When a new compound is elements combine

The new compounds produced by any chemical reaction are always totally different from the original elements or reactants.

When elements undergo a chemical reaction the product will always have a chemical formula

Compounds can split up and go back to their original element but this won't just happen by itself you will need to apply a lot of energy for it to break apart

Mixtures are substances which are not chemically joined up

A pure substance is made up of only one type of element or one type of compound. It can't be separated into anything simpler without a chemical reaction happening

A mixture contains two or more different substances. These substances aren't chemically joined up- so if you are smart then you can separate them very easily using physical methods.

Seawater and air are good examples of mixtures because they contain several different substances which aren't chemically combined

A mixture as the properties of its constituents parts

Dissolving is not disappearing

Dissolving is a common way mixtures are made

When you add a solid to a liquid the bonds holding the solute particles together can sometimes break

The solute particles then mix with the particles in the liquid then forming the solution

When the salt dissolves it is still there

If you evaporate the solvent you see the solute

Here are 7 definitions:

Solute- is the solid being dissolved

Solvent-is the liquid being dissolved into

Solution- is a mixture of a solute and a solvent that does not separate out

Soluble-means that it will dissolve

Insoluble- means that it will not dissolve

Saturated- a solution that will not dissolve any more and will solute the temperature

Solubility- a measure of how much solute will dissolve

Separating Mixtures

There are all sorts of ways you can separate mixtures. You've got to know 4 of them...

Mixtures can be separated by using physical methods

There are four separation techniques you need to be familiar with

Filtration

Evaporation

Chromatography

Distillation

All four make use of the different properties of the constituent parts to separate them out

Filtration and evaporation and Chromatography

Rock salt is simply a mixture of salts and sand that they spread on the road during winter

Salt and sand are both compounds

Different dyes in ink will wash through the paper at different rates

Some will stick to the paper and others will dissolve

Simple distillation separating pure water from ink

Simple distillation can be used for separating out a mixture of a liquid and a solid

The liquid is then heated and boiled off. It is then cooled and condensed and collected leaving the solid behind

Simple distillation is great for getting pure water from something like sea water or tap water

Fractional distillation separates mixed liquids

Fractional distillation is used to separate a mixture of liquids

Different liquids will boil off at different temperatures around their own boiling point

The fractionating column ensures that the wrong liquids condense back down and the thermometer goes to the top

When each liquid is boiled off, the temperature rises until the next fraction starts to rise