How can acetic acid be distilled by freezing as soon as its freezing suggest is over the freezing suggest of water.

Examples ~ above the web show the water part of the vinegar together ice and the mountain as a liquid yet Wikipedia shows that freezing point of acetic acid is 16.6°C.

You are watching: Theoretical freezing point of glacial acetic acid



The procedure you space describing sounds favor fractional freezing. Acetic acid is generally purified by this method, thus 100% acetic acid is often dubbed \"glacial\" acetic acid.

As an example of exactly how this works, let\"s consider a mixture the acetic acid and water.

Acetic acid has actually a freezing suggest of 16.6 oC. Water has actually a freezing suggest of 0 o. They form a eutectic in ~ -26.7 oC (although I execute not understand the composition). The phase diagram most likely looks something favor (but is not) the following.

Phase Legend:

A = fluid solutionB = Solid equipment of acetic acid in water PLUS liquid solutionC = Solid equipment of water in acetic mountain PLUS fluid solutionD = Solid equipment of acetic mountain in water E = Solid systems of water in acetic acid F = Solid solution of acetic acid in water to add Solid solution of water in acetic mountain

A mixture of acetic acid and water that is approximately 72% acetic acid is cooled till it begins to freeze (solid blue upright line), i beg your pardon happens roughly 2 oC. The phase changes from A (liquid solution) to C (Solid solution of water in acetic acid PLUS liquid solution). The solid solution is enriched in acetic acid contrasted to the initial liquid solution. The composition of the remaining supernatant liquid systems is enriched in water contrasted to the initial liquid solution. The ingredient of the solid solution can be figured out by drawing a horizontal (red) line to the phase boundary between C and E and also reading down to 91% acetic acid. The ingredient of the staying supernatant liquid solution deserve to be determined by illustration a horizontal (green) line to the phase boundary in between A and also C and reading under to 63% acetic.

See more: What Does Janai Mean In Japanese, Ja Nai And De Wa Arimasen

The supernatant step is removed and discarded, and also the solid step is enabled to melt. The process is repeated. Each successive freezing yields a brand-new solid equipment that is enriched in acetic acid, till the purity is as high together you desire it.

Note, that because water and acetic acid have a eutectic point, if we has started top top the left side of the eutectic point, the phases would have actually been reverse. The solid would be enriched in water and also the supernatant would have been enriched in acetic acid. The supernatant would certainly be remove and also kept, and also the solid would be discarded. The supernatant would then be cooled and also fractionally frozen again to additional enrich the supernatant in acetic acid till the eutectic allude is reached (at which allude the ingredient of the supernatant is equivalent to the ingredient of the heavy phase). If you want to isolation acetic mountain from a solution that is mainly water, I would certainly distil the solution until the ingredient is mainly acetic acid, and also then fractionally frozen it.