1. When preparing anhydrous ethanol in the laboratory, add calcium oxide (CaO) into 95.57% ethanol and heat and reflux (anhydrous copper sulfate can also be used). Water in alcohol reacts with calcium oxide (calcium oxide reacts with anhydrous copper sulfate to generate copper sulfate pentahydrate) to generate nonvolatile calcium hydroxide, and then distilled to obtain 99.5% anhydrous alcohol. If you want to remove this small amount of water, you can add magnesium for treatment, and you can get 100% ethanol, which is the so-called anhydrous ethanol.

2. The method of preparing anhydrous alcohol in industry is to add a certain amount of benzene to ordinary alcohol and then distill it. Boiling at 64.9℃, a ternary azeotropic mixture of benzene, ethanol and water can be distilled (the ratio is 74: 18.5: 7.5), so that all water can be distilled. The binary mixture of benzene and ethanol (the ratio is 67.6: 32.4) can be distilled at 68.3℃ by continuous heating. Finally, the temperature was raised to 78.5℃ and anhydrous ethanol was distilled. Anhydrous ethanol is prepared by strong acid cation exchange resin (with polar groups and strong water absorption) in industry.

3. Edible distilled liquor is a high-alcohol liquor extracted from fermented raw materials through one or more distillation processes. The principle of making distilled liquor is to extract high-purity liquor by evaporating alcohol according to the physical properties of alcohol. Because the vaporization point of alcohol is 78.3℃, vaporized alcohol can be obtained by reaching and maintaining this temperature. If the vaporized alcohol is input into the pipeline and cooled, it is liquid alcohol.