Absolute Alcohol Vs. Absolute alcohol

  • Thread starter Sam Morse
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I read in a book that an aqueous solution of ethanol produces a constant-boiling mixture which contains 95.6% ethanol and 4.4% water. This is called rectified spirit.

I googled the word "constant-boiling" and I came to the conclusion that it's nothing but azeotrope. But it isn't clear to me how rectified spirit is prepared. Is it true that whatever volume of alcohol is taken in water, rectified spirit is formed?

Also, I would like to know how absolute alcohol is prepared and what it is. The book says that when rectified spirit is(???? heated under reflux over quicklime ????)for about 5 to 6 hours and then allowed to stand for 12 hours, on distillation, pure alcohol is produced. What is heating under reflux over quicklime? I understand heating under reflux but what is the use of quicklime here ?
 

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  • #2
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Can you name that book(give page no. also)
 
  • #3
Borek
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I googled the word "constant-boiling" and I came to the conclusion that it's nothing but azeotrope. But it isn't clear to me how rectified spirit is prepared. Is it true that whatever volume of alcohol is taken in water, rectified spirit is formed?
Not exactly. More like if you start with any mixture of water and ethanol, and you repeat the distillation many times, each next time distilling product of the previous distillation, you will end with the azeotrope. Actually there is no need for many distillations, one done with a column is enough (equivalent to many single step procedures).

Also, I would like to know how absolute alcohol is prepared and what it is. The book says that when rectified spirit is(???? heated under reflux over quicklime ????)for about 5 to 6 hours and then allowed to stand for 12 hours, on distillation, pure alcohol is produced. What is heating under reflux over quicklime? I understand heating under reflux but what is the use of quicklime here ?
200px-Reflux_labled.svg.png


What is quicklime? What are its chemical properties? Especially in the context of water?
 

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