Reagent used to distinguish benzene from ethylbenzene

1. issues raised

In chemical production, the identification of benzene and ethylbenzene is very important. They have different uses in industrial applications. For example, benzene is commonly used in organic synthesis, while ethylbenzene is commonly used in petroleum processing and the rubber industry. Therefore, distinguishing their components is of great significance for production and quality control.

2. Reagent Selection and Identification Principle

To distinguish between benzene and ethylbenzene, the following reagents can be selected:

1. Distillation method: distillation can distinguish between the two boiling point difference.
2. Density determination: the use of both density differences for identification.
3. Illuminate reaction: through the bromine water reaction phenomenon to distinguish between the two.
4. Hydrolysis method: through the hydrolysis reaction to generate toluene ring and other products.

3. physical property identification

1. Distillation method

Distillation is the most direct way to distinguish between benzene and ethylbenzene. Benzene and ethylbenzene have different boiling points. Benzene has a boiling point of about 80°C, while ethylbenzene has a boiling point of about 115-120°C. Therefore, a mixture of the two can be easily separated by distillation.

Operation steps:

1. The benzene and ethylbenzene mixture was fed to the distillation apparatus.
2. Heat to boiling and collect the distilled liquid.
3. Depending on the distilled liquid temperature, it is possible to distinguish between benzene and ethylbenzene.

Phenomenon analysis:

in the distillation process, benzene will volatilize before ethylbenzene, so the lower temperature liquid in the distillate is benzene, and the higher temperature part is ethylbenzene.

4. chemical properties identification

1. Density determination

Benzene and ethylbenzene have slightly different densities, with benzene having a density of 0.876g/cm³ and ethylbenzene having a density of 0.874g/cm³. Although the difference is not large, the two can be distinguished by precise measurement.

Operation steps:

1. Weigh equal mass of two samples, were added to the cylinder.
2. Operation steps: observe the volume difference.

Phenomenon analysis:

although the difference is small, accurate density values can be obtained through multiple measurements to distinguish the composition of the two.

2. Oil soluble identification

Both benzene and ethylbenzene can be used as solvents, but their solubility is slightly different. For example, the solubility of bromine water in benzene is high, while the solubility of ethylbenzene is low.

Operation steps:

1. The bromine water is added to the test sample.
2. Stir well.

Phenomenon analysis:

benzene is rapidly miscible with bromine water and delaminates, while ethylbenzene may partially dissolve or not delaminate.

5. further identification

If the above method cannot distinguish between benzene and ethylbenzene, the following method can be used:

1. Hydrolysis reaction

The hydrolysis reaction of benzene and ethylbenzene with a certain reagent was carried out to observe the difference of the products.

Reagent selection:

sodium hydroxide solution or sulfuric acid can be selected.

Operation steps:

1. The sample to be tested is mixed with the NaOH solution.
2. Stir and heat.

Phenomenon analysis:

the hydrolysis of benzene in NaOH solution produces toluene ring and other products, while the reaction degree of ethylbenzene may be weak.

6. Question Summary

In distinguishing between benzene and ethylbenzene, the choice of suitable reagents and methods is very important. Distillation and densitometry are the basic methods, while Illuminate reaction and hydrolysis can provide more in-depth identification information. Through these methods, benzene and ethylbenzene can be accurately distinguished to ensure production quality and application safety.

The distinction between benzene and ethylbenzene requires a combination of physical and chemical properties, the selection of appropriate reagents and methods of operation. Only in this way can we accurately identify these two substances in a complex environment and avoid potential dangers and losses.