Crystallisation

The fourth experiment of the year ^-^ (If I'm not wrong) 

In this experiment, we were supposed to make crystals using this method called crystallisation, one of the few separating techniques we learnt. 

Basically, everyone was supposed to:

1. Mix copper (II) sulphate with water until it cannot be dissolved anymore (in the water). 
2. Then, filter out the particles that did not dissolve using filter paper. 
3. Next, we boil the filtrate, which is the liquid left after filtering out the solid particles. 
4. When half of the filtrate has evaporated, pour half of the remaining liquid into a boiling tube, and leave the other half to cool in the evaporating dish
5. Place the boiling tube in a beaker filled with ice water (rapid cooling) 

In the end, both ways of cooling the filtrate (rapid cooling and slow cooling) caused crystals to form. However, if the mixture is not saturated enough, crystals will not form (such as my group). Crystals are formed when water evaporates, which means there has to be a lot of a certain type of particle solute left to have crystals form.

Also, the type of crystals formed by rapid and slow cooling are different. Rapid cooling creates smaller and less defined crystals while slow cooling creates larger and more defined crystals. This is because slow cooling allows the crystals to take a longer time to form, resulting it to become more defined and larger.

 These are the crystals formed through rapid cooling (placed in the ice water).

These are the crystals formed through slow cooling. As you can see, one of the evaporating dishes does not contain any crystals. This is because the solution was not saturated enough (it belongs to my group). D: