Explain Some Factors That Affect Solubility

A mixture contains different substances that are not chemically joined to each other. Mixtures can contain elements and/or compounds. A solution is a type of mixture formed when a solute dissolves in a solvent. 

When something dissolves, it doesn't disappear - well it may appear like it has as you may not be able to see it - but its particles are still there. Let's zoom in on what actually happens to the particles in a solid when it dissolves.

When a solid (the solute) dissolves, the particles in that solid that are normally held tightly in place, break away from each other as they mix with the particles in the liquid (the solvent). They collide with the particles in the solvent and this is what causes the solute to dissolve and form a solution. 

Increasing the temperature of a solvent will help the solute to dissolve, but what else affects the speed at which a solute dissolves in a solvent? 

Stirring - using a spoon, stirring rod or just swirling the solvent and solute will speed up the rate of dissolving. This is because stirring causes the particles to be in rapid motion which means that the solvent molecules collide with the solute with greater frequency and with more force. Both factors increase the rate at which the solute dissolves.

If you don't stir, the solute would eventually dissolve because random motions of the water molecules would bring the particles into contact with each other, but the process would take much longer. 

Solute size - a fine powder of the solute will dissolve faster than a large piece of a solute. This is because small particles have a greater surface area with which the solvent can collide. So a spoonful of granulated sugar exposes far more surface area to the solvent and will dissolve more quickly than a sugar cube.

Let's try some questions on solubility.