Chemical mixing order question

WorryFree · Post by **WorryFree** » Wed Feb 11, 2009 1:40 am

When preparing the Ferric-EDTA bleach described on the "Rehalogenating Bleach" page of the wiki, is it unsafe (or otherwise inadvisable) to begin with a dilute solution of acetic acid and add the other ingredients to it, instead of adding the concentrated acid to the dissolved ingredients? (I'm a little hesitant to work with concentrated acetic acid.)

Solarenemy · Post by **Solarenemy** » Thu Feb 12, 2009 12:09 am

WorryFree wrote:When preparing the Ferric-EDTA bleach described on the "Rehalogenating Bleach" page of the wiki, is it unsafe (or otherwise inadvisable) to begin with a dilute solution of acetic acid and add the other ingredients to it, instead of adding the concentrated acid to the dissolved ingredients? (I'm a little hesitant to work with concentrated acetic acid.)

The formula I used for the same bleach called for Sulfuric acid. Of course in the US you need a DEA form to buy it but it is actually very easy to make. So just remember that 2.82 g of sodium bisulfate = 1 mL sulfuric acid when mixed in water. I just mixed everything in the water and added the SB last so it became acidic at the end.

When mixing acid with anything you always want to mix so the acid is the smallest of the two components being mixed. In a case where water is also used you should add all the other chemicals to the water and then add the acid. When diluting acids, always add the acid to the water. never add water to acid.

BobH · Post by **BobH** » Thu Feb 12, 2009 9:02 am

never add water to acid.

How else would you top off the fluid in a lead acid battery?

Solarenemy · Post by **Solarenemy** » Fri Feb 13, 2009 12:03 am

I believe that is an acid solution in a battery and is usually not pure undiluted acid. I also have not seen a battery that needs to be topped off in eons. Most lead acid batteries are sealed now and if they do need topping off then they should be disposed of. The point I was making is to avoid a reaction that could cause acid to splash you always want to add small quantities of acid to water, and not water to pure acid. Otherwise the acid will cause the oxygen and hydrogen in the water to decompose violently and cause splattering. At least this is what they taught us about the acids we used for etching and plating at a board house for PCB's. We had 80% nitric there that would even attack the air when it's vat was opened.