At this time, concentrated sulfuric acid and ethanol are mixed at the volume ratio of 3∶ 1, and the reason for excessive concentrated sulfuric acid is to promote the reaction in the positive direction. The experimental device is similar to the device for producing chlorine gas, and broken porcelain pieces are added to the bottom of the flask to prevent the reactants from boiling.
Insert the mercury ball of the thermometer into the mixed solution of ethanol and concentrated sulfuric acid, and quickly raise the temperature to 170℃ to prevent the by-product ether from being generated at 140℃. This reaction belongs to intermolecular dehydration reaction, rather than general intramolecular dehydration reaction.
The reason why the reaction liquid turns black when making ethylene is that ethanol and concentrated sulfuric acid undergo redox reaction, so the ethylene made in the laboratory may be mixed with impurity gases such as carbon dioxide and sulfur dioxide, which can be absorbed by sodium hydroxide solution.
Ethylene is insoluble in water and its density is close to that of air. We adopt drainage and gas collection method. Carbon dioxide, sulfur dioxide and ethanol vapor are all soluble in water, so when ethylene is collected by drainage gas collection method, carbon dioxide, sulfur dioxide gas and ethanol vapor can also be absorbed.
I hope it can help you solve the problem.