Reflux still at the molecular level?

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In summary: This allows for A to condense more readily at the top of the still, while B will remain in vapor form and continue to rise. This interaction between the condensing A and rising B allows for the separation of the two liquids in the theoretical mixture. In summary, a reflux still uses the different boiling points of two miscible liquids to separate them by condensing the higher boiling liquid at the top of the still and allowing the lower boiling liquid to continue rising as vapor. This is achieved through the molecular interactions and differences in boiling points between the two liquids.
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GiTS
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I've read info on it's operation but some questions are still unanswered. This is concerning reflux stills that create the reflux by condensing rising vapor at the top of the still.
How does the still work on a molecular level?
 
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Are you asking for a description of a phase change at the molecular level?
 
  • #3
Yes, I organized my thoughts better in the following paragraph.
A theoretical mixture is composed of liquid A and liquid B. There is more of liquid A in the mixture than liquid B and liquid B has a lower boiling point. They are fully miscible. The mixture is distilled to try to separate the two liquids. It is my understanding that when the mixture is heated both liquids will vaporize but liquid B will vaporize more. Why does liquid B vaporize more readily and what is happening on a molecular level/how are the molecules of liquid A and B interacting? In a reflux still the vapor is condensed at the top and flows back down interacting with rising vapor. Why does liquid A condense more readily than liquid B at the top of the still?
 
  • #4
Their boiling points are different. Temperature is the average kinetic energy of the molecules. In your example, a B molecule requires less energy to escape the liquid, so the higher the temperature, the more B molecules will be above their minimum threshold for evaporation, than A molecules above their (higher) minimum threshhold. Thus B evaporates at a faster rate.

At the top of the still, A has a higher boiling point and thus will condense at a higher temperature than B.
 

1. How does a reflux still work at the molecular level?

A reflux still works by heating a mixture of alcohol and water, causing the alcohol to vaporize and rise up through a column filled with packing material. As the vapor reaches the top of the column, it cools and condenses back into a liquid due to the presence of a condenser. This liquid then falls back down into the boiling flask, where it is heated again and the cycle repeats. This process allows for the separation and purification of the alcohol from other components in the mixture.

2. What is the purpose of the condenser in a reflux still?

The condenser is a crucial component of a reflux still as it helps to cool and condense the alcohol vapor back into a liquid. This allows for the separation and purification of the alcohol from other components in the mixture. The condenser works by passing cold water over the outside of the column, causing the vapor to cool and condense into a liquid which is then collected in a separate container.

3. How does a reflux still differ from a regular still at the molecular level?

A reflux still differs from a regular still in that it has a column filled with packing material which allows for more surface area for the vapor to interact with. This results in multiple rounds of vaporization and condensation, leading to a more thorough separation and purification of the alcohol. In a regular still, there is no column and the vapor is only condensed once, resulting in a less pure final product.

4. What types of molecules can be separated using a reflux still?

A reflux still is commonly used to separate and purify alcohol from water, but it can also be used to separate other types of molecules. This includes essential oils, flavors, and fragrances, as well as other organic compounds. The specific molecules that can be separated using a reflux still depend on their boiling points and the efficiency of the still.

5. What are the advantages of using a reflux still at the molecular level?

One of the main advantages of using a reflux still is that it allows for a more thorough separation and purification of the desired molecules. This results in a higher quality and more pure final product. Additionally, a reflux still is more efficient and can produce a larger quantity of the desired molecules compared to traditional distillation methods. It also allows for more precise control over the distillation process, leading to consistent and reproducible results.

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