How dangerous is Aqua regia

[martymcfly]

Ok so this is probably a no brainer. Its really dangerous . but im wondering just how much of this stuff do you have to inhale before your going to see problems?

For instance would getting a whiff from mixing a small amount like 10ml do you harm or would you have to be mixing a litre of the stuff and having serious smoke before its a proper danger?

Has anyone on here had any accidents where they have been exposed and felt ill due to it?

 

[9kuuby9]

Ok so this is probably a no brainer. Its really dangerous . but im wondering just how much of this stuff do you have to inhale before your going to see problems?

For instance would getting a whiff from mixing a small amount like 10ml do you harm or would you have to be mixing a litre of the stuff and having serious smoke before its a proper danger?

Has anyone on here had any accidents where they have been exposed and felt ill due to it?

Well the amount doesn't matter, since the damage builds up with time you should try to completely avoid it's fumes which are very harmful.

Build a fume hood or use a closed container as a vessel for your reaction vessel.

 

[solar_plasma]

I agree with 9kuuby9, blind is blind and burned lungs are burned lungs. I see a main difference between 10ml and 1 l, that 10 ml are easier to control (....or better to get under control again, if something reacts more violently), since there is 100 times more chemical energy stored in 1 l, if you start an exotherm reaction.

edit: And very important, small amounts over a long period causes diseases of the lungs without you necessarily get aware of it - similar to e-welding.

 

[martymcfly]

ive actually built my fume hood but was just wanting an idea of how dangerous ar is before i started any reactions. I read somewhere on the forum that jewelers used to smell there A/R which made me think a whiff of it must be not too bad but high exposure to it is obviously much worse.

Also once your reaction is away and in your fume hood, If you can smell the A/R is the damage already done?

 

[solar_plasma]

You do it every morning, when you inhale the exhaust from the car in front of you. But don't try this on fresh or reacting AR!

If you can smell the A/R is the damage already done?

Often you are warned by the smell, but you can't be sure of it.

 

[JHS]

Best to work under fume hood start to finnish.
john

 

[butcher]

A smell of a poisonous gas may not kill you instantly, but that would not mean that some damage is not done.

You will not fall over dead if you get a whiff of the fumes of aqua regia, but you do want to breath poisonous gases.

 

[martymcfly]

My main concern is that my fume hood is just vented straight outside and was worried that a small draft of reacting A/R fumes could blow my way and i could inhale some. Basically im treating it as if this stuff is going to kill me if i get anywhere near it but am i just being too safety conscious? Like does anyone know how much would need to be in the air to do you harm? Would your lungs be melting and coughing up blood or would it be slower to take effect?

Sorry im just paranoid about things like this.

 

[JHS]

Would it help if you raised the hight of your vent pipe?
THERE IS NO SUCH THING AS TOO SAFETY CONSIOUS
it is when we lack in safety that it become a problem

 

[solar_plasma]

Try and read the msds of HCl, HNO3, NO, NO2 and you will get a good impression. Also you will find how many ppm or mg over how long time will cause harm.

Expecting the worst case is never wrong.

 

[martymcfly]

Would it help if you raised the hight of your vent pipe?
THERE IS NO SUCH THING AS TOO SAFETY CONSIOUS
it is when we lack in safety that it become a problem

currently ive got it vented out at the maximum height i can which is about 7 foot. i managed to find some data on nitrogen dioxide:-

nitrogen dioxide

LC50 Inhalation Vapor Rat 790 mg/m3 5 minutes
LC50 Inhalation Vapor Rat 310 mg/m3 30 minutes
LC50 Inhalation Vapor Rat 220 mg/m3 1 hours
LC50 Inhalation Gas. Mouse 1000 ppm 0.67 hours
LC50 Inhalation Gas. Rat 200 ppm 30 minutes
LC50 Inhalation Gas. Rat 115 ppm 1 hours
LC50 Inhalation Gas. Rat 88 ppm 4 hours
LC50 Inhalation Gas. Rat 88 ppm 4 hours

Im not quite sure how much that is actually in the air and it deosnt state if that was the subject dead or just ill. So im guessing that a blast of fumes is not great but as long as you dont hang about in them you should be ok?

 

[solar_plasma]

and you can smell it at 0,075-0,150 mg/m³, but I would not only look on the lethal concentration, but also what is allowed in work areas.

Im not quite sure how much that is actually in the air and it deosnt state if that was the subject dead or just ill. So im guessing that a blast of fumes is not great but as long as you dont hang about in them you should be ok?

Without calculating the moles, just imagine all your 10g of acid vaporizes at once, and imagine this acid vapor is similar in its toxicity to NO2 - how many m³ air can you fill with lethal concentration? Just to get a feeling for the LC's.

LC50 5min means 50% of the rats died when they were exposed to the poison over a period of 5 minutes. LC = lethal concentration

 

[MysticColby]

I read a lot of NOx MSDS's when I started refining. From what I could tell, you can smell it at about half the concentration that it is immediately harmful to you. by 'immediately harmful', I mean the listed minimum safe exposure level. long term, low concentration, exposure can still build up and cause problems later in life.
Now the fun part: NOx also reduces your smell sensitivity. So the more you are exposed to it, the later you will realize you are exposed to it, eventually you won't be able to smell it even if it is above dangerous concentrations.
So don't cash in on your ability to detect problems because you were careless.

 

[goldsilverpro]

A friend of mine just got a fairly large burn, probably 2nd degree, on his arm from working, for a short period of time, over the hot red fumes produced from dissolving copper with nitric in a bucket.

NO2, the red fumes produced from dissolving metals in nitric or aqua regia, rats seemingly have an LD50 of 88 ppm over a 4 hour exposure. That's a little less than 1 part NO2 per 10,000 parts of air. LD50 (lethal doze for 50%) means that 50% of the rats exposed to that dosage will die. I also read that the symptoms may not show up for 72 hours.

Although the gases produced from just mixing AR are noxious and toxic, the greatest danger is the NO2 gas produced when dissolving metals.

 

[Magiskt]

Due to this topic i wonder is it possible to filter out some or most of the fumes by the vent of your fume hood?

 

[solar_plasma]

Due to this topic i wonder is it possible to filter out some or most of the fumes by the vent of your fume hood?

Yes.Try a search for "scrubber".

 

[Magiskt]

That got me to some interesting reading, thanks for the input. If I'm getting this right its the water scrubber we would like for our commonly used chemicals since they are soluble in water?

 

[9kuuby9]

That got me to some interesting reading, thanks for the input. If I'm getting this right its the water scrubber we would like for our commonly used chemicals since they are soluble in water?

Yes, Since most of the commonly used chemicals are actually "gas in water" Like HCl for instance, Cl is a gas Held by the Hydrogen atom in water.

 

[Geo]

your scrubber needs to have a basic solution instead of water. exposure to NOx fumes are two fold, immediate one time exposure to long term exposure. immediate one time exposure is measured in both concentration of fumes and length of time of exposure. symptoms of one time limited exposure can range from burning, stinging sensation on the skin to respiratory distress including inflamed mucous glands and a light cough with limited exposure. prolonged exposure to heavy fumes on a one time exposure can cause acute respiratory distress with pulmonary edema (swelling in the lungs) that have to be treated as soon as possible with steroids to avoid asphyxiation over the short term. full effects may not present for days with shortness of breath, wheezing, bloody phlegm, nose bleed, weakness and a general feeling of discomfort.

the real danger for people who work with these chemicals are long term, limited exposure of minimum concentration of fumes. exposures of concentrations too small to detect by smell is (in my opinion) very insidious in its effects. irreversible lung damage occurs with every exposure no matter how small. its an accumulative effect that resembles a long time smokers cough. these long term exposure effects will not go away by ending exposure as the damage is permanent. if you plan on working with these chemicals for any length of time, fume control should be the first and foremost priority before you begin processing.

 

[butcher]

Water will somewhat absorb some of the fumes, if the gases are in contact with the water long enough, but there are many gases that are not easily soluble in water or will not dissolve in water at all, like NO gas from nitric acid, which would pass on through the water, many scrubbers will use a chemical in solution at least in one stage of the scrubber, like a solution of NaOH to neutralize the acidic fumes and form a soluble salt from the fumes.

The scrubber can be also used to collect the gases and convert them back to acid, example NO2 gas will absorb into water forming HNO3 acid.

The clear NO gas will not dissolve in water but in oxygen (or air) can be converted to NO2 the red brown gas, if we bubble NO through a solution of hydrogen peroxide (water with an extra oxygen), the Hydrogen peroxide can convert the NO gas into NO2 and then into dilute HNO3 in the solution.

Gases can pass through a scrubber and only a portion of them may get absorbed for this reason you will normally have several stages so that more of these gases are absorbed into solution or converted to a dissolve liquid salt or an acid.