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What is crystallization? What is the use of this process?

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• August 21, 2021
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What is crystallization? What is the use of this process?

Crystallization is a processthat is often used for purifying substances that involve the separation of solids from a given solution and are also known as a separation technique.

Crystallization is defined as the process or technique in which there is an arrangement of atoms or molecules belonging to a substance. The arrangement is in the form of a well-defined 3-dimensional lattice where the overall energy is minimized in the given system. In the process of crystallization, the atoms or molecules of a substance combine forming a 3-D lattice via well-defined angles. In addition, of a solid substance to a liquid with constant stirring a point will come where the solid will be completely dissolved in the liquid  However, with constant addition, there will be a point where the solid will no longer dissolve in the liquid and this point is known as the saturation point and the fluid where the solid is being added at this point is called the saturation solution.

Crystallization Process

The crystallization process can be explained with the help of a diagram as given below:

1. The given solution is first taken in an open container and is heated.
2. The molecules of the solvent start evaporating thereby leaving the solutes behind.
3. The solutionwas allowed tocool down and then the crystals of the solute accumulate on the solution’s surface.
4. The crystals formed are then collected where it is dried as per the requirement of the final product.
5. The next step is the filtration of the undissolved solids present in the liquid.
6. The cooling rate determines the sizes of the crystal that are formed during the crystallization process. If it is cooled at a faster rate many tiny crystals will be formed. However, slow cooling rates result in larger size crystals.

Activity that can help one in understanding the crystallization technique

Here is an activity that one can do for separating substances via crystallization to understand more about the crystallization technique.

• In the first step,water is taken in a100 mL beaker.
• In Step 2 sugar is added tothe water and the solution is continuously stirred.
• After this, the solution is heated, and the process is repeated till a point comes when the sugar stops dissolving in the solvent or water. This is called the saturation point.
• Next, the sugar is filtered using a filter paper whereas the filtrate is collected in a bowl where it is cooled down. After some time, we will see the formation of crystals that are very fine in the bowl. The next filtration step will help in the separation of crystals and the liquid left behind is called the mother liquor.

What is the water of Crystallization?

The water of crystallization refers to the water molecules present in a fixed number in one unit of salt. In other words, it is used to term water that is bonded into crystals stoichiometrically. For example, a chemical, Hydrated copper sulfate has a chemical formula CuSO₄ 5H₂O. This means that the crystallization of Copper sulfateis with 5 molecules of water. The water molecules that can make a crystal structure may also be defined as water of crystallization Such water molecules form and crystallizecrystals. The CuSO₄. 5H₂O is widely used as an antibacterial and antifungal agent tropically used.

Example of Crystallization.

The crystallization of salt is the most widely practiced crystallization technique and is considered to be the cheapest or the most cost-effective technique for the preparation of salt. This technique is also used in compound purification and also for the synthesization of crystals synthesis required for various purposes.

Application of Crystallization:

1. The crystallization process is used for the purification of seawater. Crystallization techniques are usually applied in cases of separation for obtaining pure crystals which are being separated from an impure mixture. With this process, pure salts can be obtained from seawater which is required for various purposes.
2. The crystallization process helps in separating alum crystals from the impure mixture. The crystallization process is more preferable to evaporation as it also removes soluble impurities. Hence, it is more effective.
3. The crystallization process is used as the purification and separation processes in the pharmaceutical industry, for synthesizing co-crystals as well as their isolation. It also helps in the synthesize of pure API (Active Pharmaceutical Ingredients), and in controlling the release of pulmonary drug delivery, and in process of chiral isomers separation.

Two types of the crystallization process

The crystallization technique can be broadly divided into two types:

1. Evaporative crystallization
2. Cooling crystallization

Advantages of crystallization

The advantages of the crystallization technique can be discussed as under:

1. It can produce a high-quality product from just a single step i.e., the crystallization process.
2. The products thatare dried and formed by the crystallization process can be packed and stored directly in packaging things.
3. This process does not require much energy and the required temperature is relatively low.