Introduction to Matter
introduction-to-matter
Physical Nature of Matter
physical-nature-of-matter
Particles Have Space Between Them
particles-have-space
Particles Attract Each Other
particles-attract
States of Matter
states-of-matter
Change of State: Effect of Temperature
change-of-state-temperature
Sublimation and Effect of Pressure
sublimation-pressure
Evaporation
evaporation
Summary & Practice Questions
summary-questions
Pure Substances & Mixtures
pure-substances-mixtures
Types of Mixtures
types-of-mixtures
What is a Solution?
what-is-solution
Concentration of Solutions
concentration-of-solutions
Suspensions & Colloids
suspensions-colloids
Separation Techniques - Part 1
separation-techniques-1
Separation Techniques - Part 2
separation-techniques-2
Crystallisation
crystallisation
Physical & Chemical Changes
physical-chemical-changes
Elements & Compounds
elements-compounds
Crystallisation is a technique to purify solids by obtaining pure crystals from a solution.
| Step | Action |
|---|---|
| 1 | Dissolve impure solid in minimum water |
| 2 | Filter to remove insoluble impurities |
| 3 | Evaporate to get saturated solution |
| 4 | Cool slowly at room temperature |
| 5 | Crystals form |
| Issue | Evaporation | Crystallisation |
|---|---|---|
| Decomposition | ❌ Some solids decompose on heating | ✅ Gentle process |
| Charring | ❌ Sugar chars on heating to dryness | ✅ No charring |
| Impurities | ❌ Dissolved impurities contaminate solid | ✅ Pure crystals form |
✅ Purification of salt from sea water ✅ Separation of alum (phitkari) crystals ✅ Obtaining pure copper sulphate
| Mixture Type | Method |
|---|---|
| Salt from salt solution | Evaporation |
| Cream from milk | Centrifugation |
| Oil from water | Separating funnel |
| Camphor from salt | Sublimation |
| Colours from dye | Chromatography |
| Acetone from water | Distillation |
| Gases from air | Fractional distillation |
| Pure salt from impure salt | Crystallisation |