Crystallization is a process of purifying compounds by slowly evaporating a solution until the solution becomes saturated, allowing crystals to form and grow. Common salt crystals can be purified from sea water through crystallization by slowly evaporating the water at room temperature until sodium chloride crystals precipitate out of solution. Crystallization produces purer products than evaporation and takes more time but results in solid crystalline structures rather than powders.

1. Crystallization 1.Evaporate slowly at room temperature 2.Solution becomes more and more concentrated 3.Solution becomes saturated 4.Solid crystals slowly grow in size After the removal of insoluble impurities, pure crystals of common salt can be separated out by crystallization.

2. water slowly evaporates at room temperature Experiment 3.1 sodium chloride crystals sea water more concentrated solution solution saturated with respect to sodium chloride sodium chloride crystals Experiment 3.1 Example

5. sea water water turns into vapour liquid in the cold receiver test tube boiling condensing Isolation of pure water from sea water By distillation , Learning tip

6. Distillation using simple apparatus. end of delivery tube should be above the distillate delivery tube receiver test tube pure water (distillate) heat boiling tube clamp thermometer water (cooling agent) sea water anti-bumping granule (to prevent ‘bumping’ of solution) Distillation at home

7. The distillation can also be carried out using ‘Quickfit’ apparatus. The solid left behind is called the residue . The pure liquid that distils over is called the distillate .

8. A set of ‘Quickfit’ apparatus.

9. Distillation using ‘ Quickfit’ apparatus. STSE connections 3.2 heat thermometer pear-shaped flask anti-bumping granule solution Liebig condenser receiver adaptor test tube (as receiver) cold water in (from tap) water out (to sink) thermometer bulb distillate cold water Experiment 3.2 Experiment 3 .2

10. Chemical Analysis Chemical analysis Chemical identity Chemical composition