The reagent that distinguishes ethylbenzene and benzene is

Ethylbenzene and benzene are very common organic solvents in the chemical industry, but due to their similarities in physical and chemical properties, it is sometimes confusing to distinguish between them. In order to help professionals accurately identify these two liquids, this article will analyze their physical and chemical characteristics in detail, and introduce several effective methods to distinguish them.

Analysis of Basic Properties of 1.

Ethylbenzene and benzene are both colorless, odorless liquids, but they differ significantly in certain physical properties. For example, density, solubility, volatility and other indicators can be used as the main basis for distinguishing them.

2. density analysis

1. density difference Ethylbenzene has a density of about 0$(\mathrm{g/cm ^ 3})$, while benzene has a density of about $0.876$\ $(\mathrm{g/cm ^ 3})$. This means that under the same conditions (such as room temperature), ethylbenzene has a higher density than benzene, so they can be distinguished by measuring the density of the liquid.

2. Reason The ethylbenzene molecule contains a methyl group (CH$_3$), which makes the molecular weight of ethylbenzene slightly higher than benzene, and the structure of ethylbenzene molecule makes the intermolecular force relatively large in the liquid state, resulting in a higher density.

3. solubility analysis

1. solubility in water Benzene is almost insoluble in water and will form stratification when mixed, and will gradually mix after non-stratification, but it will take several hours to several days to completely mix. Ethylbenzene, on the other hand, is better miscible with water and mixes rapidly with water.

2. Solubility in carbon tetrachloride The solubility of the two in carbon tetrachloride is quite different. Benzene is practically insoluble in carbon tetrachloride, while ethylbenzene is miscible with carbon tetrachloride and mixes rapidly with carbon tetrachloride.

Volatile and odour analysis.

1. Volatile Benzene has a strong volatile, pungent smell, flammable. Ethylbenzene, on the other hand, is slightly less volatile, but is also flammable and has a less pungent odor than benzene.

2. Smell The smell of benzene is typically "burnt", while the smell of ethylbenzene is milder and smells more like an olefin.

6. physical separation method

1. liquid separation operation
   because ethylbenzene and benzene are close in some physical properties, direct liquid separation may not be effective. But it can be done:

• separatory funnel: After mixing the two, the liquid was separated by a separatory funnel. Since ethylbenzene is miscible with water and benzene is almost insoluble in water, during liquid separation, benzene will remain at the bottom of the separatory funnel, while ethylbenzene will enter another liquid separation vessel.
• Static stratification: Let the mixed liquid stand for a period of time. Because ethylbenzene is miscible with water, while benzene is almost insoluble in water, the water layer is slow, but it can also be distinguished by observing the stratification.

1. Other physical methods
   by measuring the physical properties such as density and thermal conductivity of the mixed liquid, it can also help to distinguish between ethylbenzene and benzene.

7. View Density Column

another way to quickly distinguish between ethylbenzene and benzene is to look at the density column. A density column is a vertically arranged liquid container whose density can be judged by observing the position of the liquid in the density column. Ethylbenzene has a higher density than benzene, so it will be located above the benzene in the density column.

8. identification reagent

when it cannot be directly distinguished by physical methods, specific reagents can be used for identification:

1. sodium carbide reagent The liquid to be tested is added to a test tube containing a small amount of sodium carbide and allowed to stand after shaking. If the liquid reacts fully with sodium carbide, it is ethylbenzene; if it does not react, it is benzene. This is because benzene reacts with sodium carbide, while ethylbenzene does not.

2. bromine water reagent Pour the liquid to be tested into bromine water and let stand after shaking. If the liquid is rapidly miscible with bromine water and does not separate into layers, it is ethylbenzene; if the color of bromine water rapidly fades, it is benzene. This is because benzene will undergo a weak bromination reaction with bromine water, while ethylbenzene does not undergo such a reaction.

9. considerations

in the use of identification reagents, need to pay attention to the amount of reagents and operating conditions. For example, when using sodium carbide reagent, if the amount of liquid to be tested is too large, the experimental phenomenon may not be obvious. Wear protective equipment during operation to avoid contact with hazardous substances that may be released by reagents.

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through the above analysis, we can clearly see the differences in physical and chemical properties between ethylbenzene and benzene, and through which methods can accurately recognize and distinguish them. Mastering this knowledge will help chemical practitioners to improve the accuracy of operation in practical work and avoid production or safety risks caused by confusion.