[kevinmac]

Ok here is my question. Sorry if its newbie but I am learning. From what I know that once the water has evaporated from vinegar, it is more concentrated and stronger. What is confusing is how about the acetic acid itself? doesn't that evaporate too? If you were to put vinegar on your skin and it dries up, there is still acetic acid on your skin? How long does it take the acetic acid to neutralize or evaporate?

[Corribus]

Even though water and acetic acid do not form an azeotrope, the vapor pressures of acetic acid and water are not very different, so they evaporate at similar rates. You would get some concentration as the total volume declines, but not very much.

[kevinmac]

Even though water and acetic acid do not form an azeotrope, the vapor pressures of acetic acid and water are not very different, so they evaporate at similar rates. You would get some concentration as the total volume declines, but not very much.

So, in other words, you are saying that if Vinegar has dried up from a surface, both the water and acetic acid have evaporated and there is nothing left whatsoever? It's strange because there are white residue and smell even after.

[Corribus]

Probably acetate salt or some such. Vinegar is not pure acetic solution.  There are plenty of dissolved solids and trace organics. Vinegar is natural product derived from wine, cider, etc. Even distilled vinegar will have impurities because it's diluted with water to desired strength.

[AWK]

Food grade vinegar is never a pure acetic acid solution.