Differentiation of benzene and cyclohexane

1. Basic concepts
   benzene has a density of 0.876g/cm³, which is lighter than water, and cyclohexane has a density of 0.778g/cm³, which is lighter than water but heavier than benzene. Therefore, the two substances can be distinguished by measuring the density of the liquid.
2. Operation steps

• equal volumes of water and the liquid to be tested are added to the same beaker.
• Observe whether the liquid is mixed. If the liquid to be tested floats in water, it is benzene; if it sinks in water, it is cyclohexane.
• Or directly use the density meter to measure the density value of the two liquids.

2. Solubility Identification

1. basic concepts
   benzene has a strong solubility, can dissolve a variety of organic substances, such as grease, dyes, etc.; and the solubility of cyclohexane is not as strong as benzene, especially for ionic substances.
2. Operation steps

• the same amount of salt water was added to the two liquids, and the phenomenon was observed after shaking.
• If the liquid to be tested can be mixed into salt water and make the solution uniform, it is benzene; if the liquid to be tested cannot dissolve salt and stratify, it is cyclohexane.

. 3. chemical reaction identification

1. basic concepts
   benzene and cyclohexane behave differently in chemical reactions and can be identified by certain chemical reactions.
2. Operation steps

• the liquid to be tested was added to the bromine water respectively.
• Observe the color change of the bromine water.
• If the color of bromine water fades gradually, it indicates that the liquid to be tested is benzene; if the color of bromine water does not change, it indicates that the liquid to be tested is cyclohexane.
• In addition, benzene will undergo an addition reaction in bromine water, while cyclohexane will not undergo this reaction.

4. acid potassium permanganate test

1. basic concepts
   benzene and cyclohexane react differently in acidic potassium permanganate solutions.
2. Operation steps

• an acidic potassium permanganate solution was added to each of the two liquids.
• Observe the color change.
• If the color of the acidic potassium permanganate solution gradually fades, it indicates that the liquid to be tested is benzene; if the color does not change, it indicates that the liquid to be tested is cyclohexane.

5. boiling point identification

1. basic concepts
   benzene has a boiling point of 80.1°C and cyclohexane has a boiling point of 65.4°C. Thus, the two liquids can be distinguished by the method of heating to boiling.
2. Operation steps

• the two liquids were separately poured into the same beaker and heated with an alcohol lamp.
• Observe which liquid boils first.
• The first boiling is cyclohexane, and the second boiling is benzene.

Through the above several methods, we can effectively distinguish between benzene and cyclohexane. These methods are not only suitable for laboratory, but also for simple identification in daily life.