Understand What Happens During Dissolving

A mixture contains different substances that are not chemically joined to each other.

When a solid substance dissolves into a liquid it forms a mixture.

We can explain what happens when something dissolves using ideas about particles. The particles in a solid are all held together in a fixed arrangement. When the solid dissolves, the particles come away from each other as they mix with the particles in the liquid.

We give the solid that dissolves a name - the solute. And we call the liquid that it dissolves into the solvent. The resulting mixture we call the solution.

The diagram shows how the particles behave while dissolving:

When we talk about solubility, we usually think of water as the solvent. However, water is not the only solvent and not everything dissolves in water.

For example, nail varnish does not dissolve in water - but it does in a liquid called propanone. That's why propanone is used in nail polish removers! 

Other examples include gloss paint, which cannot dissolve in water, but in a solvent called white spirit. You can't wash off gloss paint, but you can remove it with white spirit.

Want a bit more help with this before you begin? Why not watch this short video?