One For The Chemists

[banned]

Well Today I needed to do some Heat Exchanger cleaning but I couldn't find the concrete etch (phosphoric acid) I normally use. Apparently Lowe's and Home Depot don't carry it anymore now they've got something safer without acid in it. So I hunt around and scrounge up 6 gallons of concrete etch with phosphoric acid in it. I start the circulation process with plain water then add 2 gallons of the phosphoric. It's working but I'm not certain it's strong enough so I decide to add 1/2 gallon of muriatic acid. Now it's bubbling a little and appears to be working. A few minutes later it starts getting violent and starts producing a thick black smoke. Luckily I had a way to direct the discharge out of the boat and dilute the input with water.

So what happened? Does mixing muriatic and phosphoric cause a reaction? What was the black smoke all about?

Brian

[lcruiser]

sorry to LOL but that was kinda funny. I'm not a chemist but I'm fairly certain the strength of the muriatic acid is waaaaaay up there compared to the phosphoric... HD still carries some of the "green acid' by a different name I think.. if not, probably a paint store may carry it...

if you used muriatic it's probably clean NOW...

[krush]

Why don't you ask over on the other forums....buahahha

[banned]

It more than just a strength issue I've done this with muriatic and you have to dilute more. This was a reaction of some kind. I've learned that chlorine and muriatic will react like this they even mention a thick black vapor. The problem is that chlorine is not listed as an ingredient in the concrete etch.

Krush I don't post on the other forum I refuse to subject myself to Nazi behavior.


Brian

[badhattitude]

What was the ingredients in the other stuff? It's hard to determine what reacted if we don't know what was in it.

[banned]

Label states Phosphoric Acid Nitric Acid and Water It doesn't show the percentages.


Brian

[badhattitude]

I believe the hydrochloric and nitric acids can dissolve noble metals. That could be the reaction you saw.

Mixing 2 acids can change the properties of what it will dissolve and could be dangerous.

[banned]

I think your right here's a description of what happens when nitric acid is mixed with hydrochloric (muriatic) Acid

1.General Description: Hydrochloric acid, mixed with nitric acid (3:1) (CAS NO.8007-56-5) is a yellow liquid with a pungent odor prepared by mixing nitric acid and hydrochloric acid, usually in a ratio of one part of nitric acid to three or four parts of hydrochloric acid. Fumes are irritating to the eyes and mucous membranes. Corrosive to metals and to tissue.
2.Air & Water: Reactions Fumes in air. Soluble in water with release of heat.
3.Reactivity Profile: Nitrohydrochloric acid is a powerful oxidizing agent and a strong acid. Reacts exothermically with chemical bases (for example: amines and inorganic hydroxides) to form salts and water. Reacts with most metals, including gold and platinum, to dissolve them with generation of toxic and/or flammable gases. Can initiate polymerization in polymerizable organic compounds. Reacts with cyanide salts to generate toxic hydrogen cyanide gas. Generates flammable and/or toxic gases with dithiocarbamates, isocyanates, mercaptans, nitrides, nitriles, sulfides, and weak or strong reducing agents. Additional exothermic gas-generating reactions occur with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), and carbonates (CO2).
4.Health Hazard :TOXIC; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance may cause severe injury, burns or death. Reaction with water or moist air will release toxic, corrosive or flammable gases. Reaction with water may generate much heat that will increase the concentration of fumes in the air. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.
5.Fire Hazard: Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Vapors may accumulate in confined areas (basement, tanks, hopper/tank cars etc.). Substance will react with water (some violently), releasing corrosive and/or toxic gases and runoff. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water.

[badhattitude]

And the molarity of the Hydrochloric is probably 6-8 times the nitric.

[banned]

And that's what you need to watch out for the molarity will get you every time!!!

WTF is molarity?


Brian

Isnt that the propensity to beez thinkin' like a molanjohn?? ws