1. Chapter 18 Solutions and Crystallisation Solution – A solid dissolved in a liquid e.g. seawater Can you think of other solutions?

2. Solutes, Solvents and solutions Solute – The substance that dissolves e.g. sugar or salt Solvent – The liquid the solute dissolves in e.g. water, oil Solution – When the solute dissolves in the solvent e.g. sea water Concentrated and Dilute Solutions Concentrated solution e.g. Ribena concentrate. It tastes very sweet and has a dark purple colour. There are a lot of ribena molecules (solute) present In a concentrated solution (solvent).

3. When you add water to the concentrated ribena you make a dilute solution. What happens to the colour of the solution, the taste of the solution? A dilute solution has a small number of solute molecules dissolved In it. Soluble and Insoluble Soluble: If a substance dissolves in a solvent it is said to be soluble. e.g. salt in water Insoluble: If a substance does not dissolve in a solvent it is said to be insoluble e.g. salt in oil

4. Suspension – When a solid settles to the bottom of a liquid or scatters throughout the liquid it forms a suspension e.g. milk is a suspension of oil in water or soil in water Solubility – How much of a substance will dissolve. The amount of solute e.g. salt that dissolves depends on: Solubility of solutes usually increases with temperature. (exception is oxygen dissolved in water).

8. Solubility Curves A solubility curve plots the mass of solute dissolved in a saturated solution at different temperatures. The graph shows the solubility of copper sulphate increases as the temperature of the solvent increases.

9. Crystallisation – The formation of crystals by cooling a saturated solution. Crystals are tiny particles built in a regular manner e.g. salt, diamonds, snowflakes When a hot saturated solution of copper sulphate is cooled down some of the copper sulphate will come out of solution and form crystals. The more slowly you cool the solution the bigger the crystals are.