Azeotrope Examples

A binary mixture of two or more liquids that boils at a constant temperature and a given pressure shows a similarity in the concentration and their composition both in liquid and vapour phases: this is said to be an azeotrope mixture. In such mixtures, one component is more volatile than the other. The pressure is called azeotropic pressure. The temperature is called azeotropic temperature. Fractional distillation is called the separation method that separates the azeotrope mixtures. Compounds like benzene and toluene form suitable azeotropes when mixed with water. Both compounds are taken in fixed compositions to form an azeotrope.

Azeotrope distillation 

Here’s some essential information about the azeotrope distillation process: 

• Azeotrope distillation is the process of separating two different volatile mixtures in a boiling liquid mixture. 
• Azeotropic distillation is an essential and unique distillation process that is commonly used in laboratories and industries.
• An azeotrope mixture cannot be separated by the normal distillation method, so an additional third component is added to the mixture.
• The third additional component is called entrainer. 
• Entrainer increases the volatility of one of the liquids, making it more significant than the other, allowing the separation. 
• Generally, an azeotropic agent is added with the charge. Then, the distillation continues until all components are removed, leaving only the azeotropic agent and the bottom product as the remaining component.

 What are the types of azeotrope mixtures?

Using Raoult’s law derivations, the azeotropic mixtures are divided into four types based on their composition. They’re as stated below: 

•  Heterogeneous & homogeneous azeotrope

Heterogeneous azeotropes are not completely miscible. For example, an aqueous mixture of chloroform and water is an example of a heterogeneous azeotrope. On the other hand, homogeneous azeotropes’ constituents are completely miscible. Therefore, any percentage of ethanol can be added to water to form a homogeneous azeotropic mixture.

•  Minimum boiling azeotrope

The azeotropes whose boiling point is less/lower than their pure constituent component are called minimum boiling azeotropes.  They are also known as positive azeotropes as they show large positive deviations from Raoult’s law at given composition. For example, water and ethanol. Water boils at 1000C while ethanol boils at 78.50C, and this azeotropic mixture boils at 78.20C.

•  Maximum boiling azeotrope

The azeotropes whose boiling point is higher than their constituent of the pure components are called maximum boiling azeotropes. They are also known as negative azeotropes as they show large negative deviations from Raoult’s law at given composition. For example, water and hydrogen chloride. Water boils at 1000C while HCl boils at -840C and this azeotropic mixture boils at 1100C.

•  Binary azeotrope

Azeotropes having two constituents are known as binary azeotropes—for example, a mixture of diethyl ether and halothane.

Give some examples of azeotrope 

Here are some examples of azeotropes:

• The mixture of diethyl ether 33% and halothane 66% is commonly used for making anaesthesia. 
• The mixture of water and hydrogen chloride. Water boils at 1000C while HCl boils at -840C and this azeotropic mixture boils at 1100C.
• The mixture of water and ethanol. Water boils at 1000C and ethanol boils at 78.50C and this azeotropic mixture boils at 78.20C.
• The mixture of chloroform and water.
• The mixture of ethyl alcohol 96% and water 4% boils at 78.10C. 
•  The mixture of nitric acid 68% and water 32%  boils at 120.4 °C.
• The mixture of hydrofluoric acid 35.6% and water 64.4% boils at 111.35°C.
• The perchloric acid mixture 71.6% and water 28.4% boils at 203°C.
• The mixture of sulfuric acid 98.3% and water 1.7% boils at 338°C.
• The mixture of 1.2% water and 98.8% diethyl ether.
• The mixture of 30% acetone, 47% chloroform, and 23% methanol boils at 57.5 °C.
• The mixture of water 13.5% and toluene 86.5% boils at 84.1°C.
• The water mixture 1.3% and diethyl ether 98.7% boils at 34.2°C.
• The mixture of water 1.4% and pentane 98.6% boils at 34.6°C.
• The mixture of methanol 12.1% and ketone 87.9% boils at 55.5°C.
• The mixture of methanol 72.5% and toluene 32.0% boils at 63.5°C.
• The mixture of ethanol 68.0% and toluene 32.0% boils at 76.7°C.

Conclusion

In this topic, we learned about azeotropes. Then we studied azeotropes mixtures in detail. We also discussed the azeotrope distillation. Then we saw the types of azeotropic mixtures. Also, various azeotrope examples are included to understand the topic better. It is a very crucial topic for chemistry students. It is also helpful for students or aspirants appearing in IIT/JEE/NEET exams.