Difference between Crystalline and Amorphous Solids:
The amorphous solids are formed in the process of crystallization. An antibiotic, chloramphenicol, exists in three crystalline forms and an amorphous form while novobiocin exist in amorphous form. The former antibiotic is inactive in crystalline form whereas the latter shows rapid absorption in GIT with a good therapeutic response. For stability, crystalline forms have better stability over amorphous forms. The crystalline form of penicillin G sodium or potassium salt is more stable than its corresponding amorphous form. The crystal lattice of the drug has to be disrupted by solvent before the drug can dissolve. In crystal form, molecules are held tightly therefore driving force for the drug to dissolve is low. Hence crystalline forms have lower intrinsic solubilities compared to amorphous forms. The Difference between Crystalline and Amorphous Solidsin Table below.
Crystalline Solids | Amorphous Solids |
1. Crystalline solids are arranged in a neat and orderly fashion as fixed 3D crystal lattice or geometric patterns. Examples are ice, methanol, penicillin G, and sodium chloride. | 1. Amorphous solids are just strewn in any old fashion with random unoriented molecules. Examples are glass, plastic, penicillin G, and novobiocin. |
2. Practically incompressible. | 2. Practically compressible. |
3. Crystalline solids show a definite melting point so they pass sharply from solid to liquid state… | 3. Amorphous solids do not show a definite melting point so the transition from solid to liquid takes place at a wide temperature range. |
4. Higher energy is required for a molecule to escape from a crystal form. | 4. Low energy is required for a molecule to escape from an amorphous form. |
5. Take less time to remove solvent through the space between crystals | 5. Take comparatively more time to remove solvent and is removed by diffusion. |
6. Handling quality of crystalline materials is poor. | 6. Handling quality of amorphous materials is better. |
7. Shows poor aqueous solubility because more energy is required by orderly arranged molecules for dissolution. | 7. Shows good aqueous solubility because minimal energy is required by randomly arranged molecules for dissolution. |
8. In crystalline solids melting happens. | 8. In amorphous form glass transition happens. |
9. When a crystalline solid is heated at a constant rate, the temperature increases at a constant rate. | 9. When a crystalline solid is heated at a constant rate, the temperature increases at different rates. |
10. They show poor absorption and low bioavailability. | 10. They are rapidly absorbed and show higher bioavailability. |
11. These solids are stable than amorphous solids. | 11. They are less stable than crystalline solids. |
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