Crystallization Process

The crystallization process consists of two major events. One is nucleation and the other is crystal growth which both are driven by thermodynamic properties also as chemical properties. Nucleation is the primary step where the solute molecules or atoms dispersed within the solvent start to collect into clusters, that become stable under the present operating conditions. These stable clusters constitute the nuclei. Therefore, the clusters got to reach a critical size so as to become stable nuclei. It’s at the stage of nucleation that the atoms or molecules are arranged in a defined and periodic manner that defines the crystal structure.

Crystal growth refers to the increase in the size of the nuclei which is able to achieve the critical cluster size. Many compounds have the power to crystallize with some having different crystal structures, a phenomenon called polymorphism. Certain polymorphs can be metastable, meaning that although it’s not in thermodynamic equilibrium, they are kinetically stable and requires some input of energy to initiate a change to the equilibrium phase.

Theory of Crystallization

The three major stages in the process of Crystallization are:

• Supersaturation of Solution: It can be done in three ways: Heating the solution, Cooling the solution, and Salting it out.
• Nucleation: This takes place in several steps. During their random motion, the atoms/ molecules/ ions will come closer to one another and form aggregates called Clusters. These clusters will combine to form an EMBRYO. In this stage, only the lattice formation begins. These embryos combine to form NUCLEI. From nuclei, crystals are formed.
• Crystal Growth: Once the crystals are formed, nuclei formation stops and crystal growth begins.

Water of Crystallization  

The number of water molecules that combine with other molecules in definite proportions to form a crystal structure is called the water of crystallization. This water of crystalization is responsible for the shape and color of the crystal. For Example in Washing Soda, Na₂CO₃.10H₂O, the water of crystallization is 10.

Learn more about Water of Crystallization

Crystallization is a technique for purification of the substances. It is a technique that separates a solid from its solution. The process in which the solid dissolve in the liquid arranges itself in well-defined 3-D structures called the crystal is called crystallization. When any substance undergoes crystallization its molecule arranges itself in a fixed structure at an angle to form a 3-D structure called the crystal and then the crystal is removed from the solution. The crystal is a pure substance and thus the process of crystalization is widely used in the purification of material from its impure solution.

In this article, we will learn about crystallization, the process used for crystallization, its example, and its application in detail in this article.

Table of Contents 

• Definition
• Examples
• Crystallization Process 
• Crystallization of Salt
• Types of Crystallization
• Factors Affecting Crystallization
• Applications
• FAQs