More about solutions
Solutions are a type of mixture. They are made of a solute and a solvent.
If we take the easy example of salt water, the substance that dissolves (the salt) is called the solute and the substance it dissolves in (the water) is called the solvent.
To make a basic solution all you need to do is put a solute in a solvent. The solute will start to break into pieces, and if you stir it, it will break down even faster. The molecules of the solvent will move out of the way, making room for the solute. Finally the concentration of the solute and solvent becomes equal.
Solubility is the ability of the solute to dissolve in the solvent. It varies according to three main factors:
Heat makes it easier to dissolve, which is why it’s easier to mix sugar in hot tea than cold tea.
Higher pressure makes it easier for gas to dissolve in liquid. This is how fizzy drinks are made. The gas is pushed into the liquid thanks to high pressure.
Some solutes dissolve easier than others. Sugar has an easy structure to dissolve in liquid, whereas oil does not. In fact, oil is not soluble in water so it cannot distribute evenly. It cannot make a solution. Oil and water is a mixture.
Homogeneous mixtures
An alloy is a combination of metals or of a metal and another element. Steel is an alloy made from mixing iron and carbon.
Solutions are homogeneous mixtures.
Heterogeneous mixtures
Suspensions are mixtures between solid particles and liquids. An example is sand in water. The solid particles do not dissolve. With time, the solid particles settle and separate.
Colloids are evenly distributed mixes (like solutions) but the particles do not fully dissolve, they are suspended in the solution. Examples of colloids are clouds, smoke and shampoo. Emulsions are colloids that mix oil and water. Milk is an emulsion, a mixture of butter fat (oil) in water.
The difference between suspensions and colloids is that in colloids particles do not settle to the bottom.
