Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: Timothy Terwilliker on 23/02/2019 23:12:05

Title: Is there a way to separate the HCl from a mixture of salt and vinegar?
Post by: Timothy Terwilliker on 23/02/2019 23:12:05

I've heard that when salt and vinegar are mixed a small amount of HCi is formed how could one go about separating the HCi from the rest of the mix?

Title: Re: Is there a way to separate the HCl from a mixture of salt and vinegar?
Post by: chiralSPO on 24/02/2019 01:29:08

Sodium chloride and vinegar will not be a useful combination for distilling HCl.

The pK_a of acetic acid (the acid in vinegar) is more than 12 units above the pK_a of hydrochloric acid (4.8 vs about –9), so the concentration of HCl could never be more than one trillionth of the concentration of acetic acid (and vinegar is about 5% acetic acid). Also, acetic acid and water are both fairly volatile, so you would probably just end up distilling water and then acetic acid, leaving sodium chloride behind.

It is possible to convert sodium chloride into hydrochloric acid by adding acid and distilling, if one uses much stronger acid with a much higher boiling point (and little to no water). I believe that sulfuric acid and phosphoric acid both would do the trick.

However, I should note that pure, hot, gaseous HCl is *extremely dangerous.* If you don't have the right equipment to condense it, or aren't working with enough ventilation, or something goes wrong, you could easily *permanently* damage your eyes and/or lungs. HCl can be purchased (in multiple concentrations), and this is a much safer way to get it (cold dilute aqueous solutions of HCl can still blind you, but at least you are unlikely to kill yourself with them...)