Potential hazards of silver nitrate

[Primarygun]

A bottle of silver nitrate solution is labelled "corrosive".

That's what I read from my book and web sites.

However, when I was carrying out the silver nitrate test, my teacher did not give my class any pieces of advice.

Here, I found a web site [you don't need to really browse it]

http://www.jtbaker.com/msds/englishhtml/S2282.htm

Skin Contact:

Immediately flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Get medical attention immediately. Wash clothing before reuse. Thoroughly clean shoes before reuse. [/Quote]

Can anyone tell me why this treatment is necessary?

[YT2095]

the silver ion is very easily displaced from the nitrate ion, making it corrosive by liberation of NO2, the silver metal when in contact with your skin will turn it black also upon exposure to UV light (ordinary daylight is enough), although it`s not in itself toxic per se, there is a condition called Argeria in which the person exposed to excess silver will actualy turn Grey!

the problem is mostly with the nitrate ion, it will necrotise skin on contact.

[bascule]

Interesting to hear that from someone else because my friend who works at Kodak said the exact same thing about their silver nitrate.

[YT2095]

that would make sense also, as silver nitrate was the chemical used to make the 1`st photographic plates

 

Gold is also used (not as the nitrate) and that will send your fingers Purple!

again, it requires a little UV exposure also.

[woelen]

Well, in fact, the nitrate ion is not needed at all to make your fingers black. Any silver salt will do. I have some silver sulphamate and this equally makes your fingers black, while the sulphamate ion is quite unreactive (inert).

 

What happens is that silver ions are quite strong oxidizers, the silver itself being reduced to metallic silver (causing grey/black stains on the skin) and destroying the skin, which is being oxidized. The nitrate ion hardly has any effect. I know the same effect from any soluble silver salt.

 

Chemically speaking, silver ions and nitrate ions do not react at all. Nitrate in fact is quite stable in aqueous solutions, unless the pH is very low and concentration is high, as in nitric acid.

 

For photographic purposes, silver chloride and bromide are used. The silver then is reduced by the developer and the bromide or chloride remains behind in solution. Black stains also are obtained, when silver chloride is on the skin for a longer time.

[jdurg]

One must also realize that the silver ion is actually moderately toxic and not something you want a lot of in your body.

[Nevermore]

^^The same is true of everything.

[Nashyboyo]

For photographic purposes, silver chloride and bromide are used. The silver then is reduced by the developer and the bromide or chloride remains behind in solution. Black stains also are obtained, when silver chloride is on the skin for a longer time.

 

Does this mean that if all the silver chloride is used up then all that remains is a solutoin of chlorine? Isn't chlorine a gas? What's left behind must be a salt of chlorine or bound to some non-metal ? If true what would that be?

 

Cheers

[woelen]

No, no chlorine remains behind, but chloride.

 

AgCl consists of Ag(+) ions and Cl(-) ions. The Ag(+) ions are reduced to metallic Ag and the chloride ions remain behind as Cl(-). The reducing agent is the photographic developer, which frequently is a complex of hydroquinone and sulfite, but compounds like pyrogallol, catechol, or even vitamin C also act as reductor.

 

What remains in solution is chloride ion and some oxidizer species, derived from the developer. These oxidized species are very complicated, often polymeric/condensed organic molecules and cations.

[YT2095]

What happens is that silver ions are quite strong oxidizers.

 

HUH!?

 

more like it`s not a very good reducer perhaps, but silver as an Oxidiser???

the Nitrate ion is what causes the Damage, and silver isn`t what I`de consider even a Moderate toxin, any more than Iron is.

[jdurg]

HUH!?

 

more like it`s not a very good reducer perhaps' date=' but silver as an Oxidiser???

the Nitrate ion is what causes the Damage, and silver isn`t what I`de consider even a Moderate toxin, any more than Iron is.[/quote']

 

Take a look at the link I've posted below YT. Silver is NOT some non-toxic compound. It is FAR more toxic than Iron is, despite your disbelief. Silver competes with hemoglobin in the blood in terms of its affinity for oxygen, and it also deposits readily in tissues damaging their structures. Approximately 10 grams of AgNO3, when ingested, is fatal to man. I HIGHLY doubt that 10 grams of Fe(NO3)2 would be fatal to a human if he/she ingested it.

 

http://www.inchem.org/documents/jecfa/jecmono/v12je19.htm

[woelen]

HUH!?

 

more like it`s not a very good reducer perhaps' date=' but silver as an Oxidiser???

the Nitrate ion is what causes the Damage, and silver isn`t what I`de consider even a Moderate toxin, any more than Iron is.[/quote']

YT, silver ion really IS quite a strong oxidizer. The nitrate ion does not do anything in your case, it is the silver ion which is the active species. As I told before, ANY soluble silver salt has the blackening effect on skin and ANY soluble silver salt is quite toxic, as jdurg pointed out, because of the oxidizing properties of Ag(+) ion. I even have a nice demonstration of the powerful oxidizing properties of Ag(+). Mix some soluble silver salt with powdered magnesium and add a drop of water. Instant flash and your silver ions form silver and the magnesium is converted to Mg(2+) ion. Be careful though, this is an EXTREMELY hot and violent reaction: 1000+ C at once after adding the drop of water! Have a look on my site for this experiment.

[Primarygun]

The decomposition of this nitrate at room temperature should be slow, right?

Before your tellings, I didn't think of any possibility that silver oxide would do so much hurts to us.

My brain was covered by the gravity of the serious corrosion by halogens.

http://en.wikipedia.org/wiki/Sodium_carbonate

Anyone knows why sodium carbonate is more harmful than silver nitrate?

On the right hand side, the harmful level is 2 while that of silver nitrate is only 1.

Have a look at this.

http://en.wikipedia.org/wiki/NFPA_704

[YT2095]

YT, silver ion really IS quite a strong oxidizer. The nitrate ion does not do anything in your case, it is the silver ion which is the active species. As I told before, ANY soluble silver salt has the blackening effect on skin and ANY soluble silver salt is quite toxic, as jdurg pointed out, because of the oxidizing properties of Ag(+) ion. I even have a nice demonstration of the powerful oxidizing properties of Ag(+). Mix some soluble silver salt with powdered magnesium and add a drop of water. Instant flash and your silver ions form silver and the magnesium is converted to Mg(2+) ion. Be careful though, this is an EXTREMELY hot and violent reaction: 1000+ C at once after adding the drop of water! Have a look on my site for this experiment.

 

if silver was a strong oxidiser, then silver metal and Mg metal should react without the silver having to be a salt, and they don`t.

also I`m familiar with other silver salts and them making digits go black, but this was on about the Nitrate, so I only spoke of that, the liberation of the nitrate ion DOES cause skin damage also, one only need note the yellowing of fingers after exposure to nitric acid, I never mentioned that being the cause of the blackening, only the necrotising effect (often not seen because the silver particles are far more noticable).

as for it`s Toxicity, it isn`t considered a toxic metal, and to say that TEN GRAMS will kill you, well I`m not surprised, that`s quite alot!

[woelen]

if silver was a strong oxidiser, then silver metal and Mg metal should react without the silver having to be a salt, and they don`t.

Silver ion is a strong oxidizer, not silver metal. Silver metal is the reduced form of the oxidizing ionic species. It is essential that the silver is in a salt, because then it is Ag(+), while in the metal it is Ag(0). Think of this, this is a VERY important difference. E.g. Na(+) in table salt is inert and harmless, while Na(0), the metal is a very strong reductor. You cannot simply compare metals and the derived ions with each other, they are TOTALLY different.

 

also I`m familiar with other silver salts and them making digits go black, but this was on about the Nitrate, so I only spoke of that, the liberation of the nitrate ion DOES cause skin damage also, one only need note the yellowing of fingers after exposure to nitric acid, I never mentioned that being the cause of the blackening, only the necrotising effect (often not seen because the silver particles are far more noticable).

The effect of nitrate only exists at high temperatures (as in fireworks) or at very high concentration and low pH (as in nitric acid). Nitrate ion without acid at low temperature really is very inert. Just take some NaNO3 or KNO3 and rub your hands with that for minutes. Nothing happens, at least not more than when you rub your hands with e.g. table salt. Also, if you take a concentrated solution of NaNO3 or KNO3, then nothing special happens with your skin. AgNO3 kills your skin, due to the Ag(+) ions, and HNO3 kills your skin, not because of presence of NO3(-) ions, but because of presence of HNO3 molecules. Again, these are very different from nitrate ion.

 

An even more striking example is the perchlorate ion. The ion ClO4(-) is even more inert than the dull chloride ion at low temperature. And this remains so, with concentrations of even up to 60% by weight. Only when the perchlorate becomes covalently bound, then it becomes extremely reactive and corrosive.

So, KClO4 (ionic compound) is inert at room temp (not at high temps as in fireworks) and also dilute perchloric acid H(+)/ClO4(-) is "inert" at concentrations up to 72% (only acidic, not strongly oxidizing). Above that concentration, covalent HClO4 molecules are formed and at those concentrations the compound becomes very corrosive (e.g. to skin) and also very reactive and dangerous (liable to cause explosions with reducing agents).

 

as for it`s Toxicity, it isn`t considered a toxic metal, and to say that TEN GRAMS will kill you, well I`m not surprised, that`s quite alot!

Silver metal indeed is not very toxic, but silver ion is among the more toxic ions. Again, ions and free elements cannot simply be compared, they are totally different.

[YT2095]

so in the case of silver nitrate your saying the Silver Ion is the oxidiser and so therefore the Nitrate is the reducer?

 

that doesn`t sit right somehow, what in the case of Silver Oxide?

[jdurg]

so in the case of silver nitrate your saying the Silver Ion is the oxidiser and so therefore the Nitrate is the reducer?

 

that doesn`t sit right somehow' date=' what in the case of Silver Oxide?[/quote']

 

Not neccesarily. You typically see the Ag+ ion oxidizing everything else. It'll take electrons from your skin, a piece of paper, anything else around it, etc. etc. In the case of AgNO3 crystals darkening, then indeed one could say that the nitrate is "acting" as a reducer. In reality, what's happening is that the UV rays are striking the AgNO3 crystals causing electrons to move around. In most cases, nothing happens with a crystalline solid because the moved electrons go right back to where they were. With AgNO3, because Ag+ is indeed a stronger oxidizer, it grabs that free electron bumped off of the nitrate ion by the UV light and immediately forms silver metal. In this instance, Ag+ is a stronger oxidizer than NO3- so one could say that NO3- is the reducing agent, but in reality it's the UV light which is causing the reaction. You don't see this occuring with things like KNO3 because NO3- is a much stronger oxidizer than K+ is. When that UV light strikes the crystal structure, the NO3- readily grabs back the electron that was temporarily knocked free.

 

If what has been said above is indeed true, then one would also see that the NO3 left over would probably decompose pretty quickly into NO and O2 which would then go on and oxidize whatever the silver nitrate is touching, hence why it is so good at killing things.

[woelen]

so in the case of silver nitrate your saying the Silver Ion is the oxidiser and so therefore the Nitrate is the reducer?

 

that doesn`t sit right somehow' date=' what in the case of Silver Oxide?[/quote']

As Jdurg stated it, the Ag(+) ion is the oxidizer and the skin, piece of paper, etc. is the reductor. With such (organic) compounds around, the nitrate ion is not affected, it is the other compound which is affected.

 

I have done experiments with AgNO3, exposed to light. It appears that AgNO3 itself does not discolor, it remains purely white like snow. But even when trace amounts of organic substances are present, then it becomes grey.

 

If you have some AgNO3 then do the following:

Take a small glass vial and put a spatula of the white solid in it. Cap this vial tightly and put at a light place. Nothing happens with the AgNO3, not even when it is in the sun.

Next, do the same experiment, but allow the vial to be open (dust coming in, but also organic matter from the atmosphere, e.g. your breathe, etc.). If you now put the vial in light, then it becomes dark within a few days.

 

Back to your Ag2O (a black powder). This is a strong oxidizer, not because of the oxygen in it, but because of the two Ag(+) ions. Mixing Ag2O with Mg metal makes an extremely powerful and energetic material (be careful, this is a dangerous mix). Yes, YT, it may surprise you, but the chemistry of silver ions is quite interesting and unexpected.

If you have AgCl, then it turns purple, when light falls on it, even if left on its own without any reductor around. If I'm home, I can post pictures of this purple stuff over here. What happens is that (as Jdurg states) AgCl is excited and Ag picks an electron from Cl. The Cl escapes as radical (forming Cl2 with other radicals). What remains behind is a crystal lattice irregularity (Ag atom instead of ion and missing Cl ion). More than 99.99...% of the AgCl remains unchanged, but the tiny amount of altered lattice is sufficient to give it a strange purple color. These lattice deficiencies also are starting seeds for photographic developers, at those points reduction to metallic silver is more facile than on unexposed places and this is the underlying principle of good old B&W photography.

[YT2095]

ok lets see if we`re on the same wavelength here, would you concur that that the Black discoloration is Silver metal (just a very very fine particulate of this metal)?

 

lets deal with that part first

 

 

and also as for pure silver nitrate, I agree in direct sun it alone won`t change color, what happens is that when you get it on your hands it takes the Salt from perspiration (nacl) and reacts forming silver chloride and sodium nitrate, on later UV exposure the clorine is liberated leaving the silver metal embeded in your pores.

[woelen]

Yes, the black material consists of fine silver particles. This is the idea behind black and white photography. The black parts of an old black and white picture are made of many ultrafine metallic silver particles, immersed in the gelatin of the photo paper.

 

A few links on the oxidizing properties of Ag(+) ions and the black particles of metallic silver, which are formed when the Ag(+) is reduced to Ag:

http://www.uni-regensburg.de/Fakultaeten/nat_Fak_IV/Organische_Chemie/Didaktik/Keusch/p14_hyd_ag-e.htm

http://www.chemistry.usna.edu/manual/Ex35.pdf

 

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Now the second part. When AgNO3 comes in contact with your skin, then the following happens:

 

AgNO3 --> Ag(+) + NO3(-) (dissolving of the salt)

 

Ag(+) + X --> Ag + X(+)

 

Here X is a (possibly large) molecule from your skin, some proteinic particle, whatever organic oxidizable compound. So, the skin is the reductor, and NaCl present on your skin is not important at all. Also, light is not important in this particular situation. Put some AgNO3 on your skin, and even in total darkness it will stain your skin.

 

So, there are two different things to be distinguished:

1) The ease at which Ag(+) ion is excited and made to react with other things by means of light. This is exploited in photography.

2) The ease at which Ag(+) ion is capable of oxidizing organic matter, such as skin, dust, paper, etc. This happens even in the dark.

 

When (1) and (2) are combined, then we enter the area of photography. Photo paper contains AgCl (or AgBr or a mix of both) and this is reduced easily, itself acting as oxidizer:

 

AgCl + dev --> Ag + Cl(-) + dev(+), where dev is a developer molecule.

 

This reaction occurs anyway, whether the AgCl is exposed to light or not. But... where the solid is exposed to light, at those places, there already are some Ag atoms, dissociated from the halogen atom. At these places, the developer acts faster than on other places. So, by adjusting the time that the print is in the development bath, one can control how the image looks like. It is important to keep the photo paper with the AgCl/AgBr for such a long time in the bath, that the exposed areas already are reduced (made black), while the unexposed areas still remain white (not yet reacted AgBr/AgCl). The precise chemistry and physics behind this is amazingly complex, but a simplyfied explanation, quite understandable is given in the link below:

 

http://science.csustan.edu/nhuy/chem1002/photoexp.htm

[YT2095]

NaCl present on your skin is not important at all. Also' date=' light is not important in this particular situation. Put some AgNO3 on your skin, and even in total darkness it will stain your skin.

[/quote']

 

are you SURE about this? because mine doesn`t, and yes I have tested this above once and with several different people!?

also silver nitrate soaked filter paper even in bright sunlight takes days to react, unless you spray on a little salt water, then it takes only minutes.

and yes I`ve tested that above once also

[woelen]

are you SURE about this? because mine doesn`t' date=' and yes I have tested this above once and with several different people!?

also silver nitrate soaked filter paper even in bright sunlight takes days to react, unless you spray on a little salt water, then it takes only minutes.

and yes I`ve tested that above once also [/quote']

Yes, the latter can be explained, because of the formation of AgCl and the effect, I described with photography. With AgNO3, latent images (see link I posted) cannot be formed, with AgCl or AgBr these latent images are formed and at those places, the blackening occurs much faster, in your case, the paper acting as reductor. For this reason, silver halogenides (except the fluoride) are used in photography, because the halogen ions can be ripped sufficiently easy by the Ag(+) ion to give off their electron. Nitrate ions are not that easily ripped. Formation of latent images (the irregularities in the crystal lattice) are the cause of much easier reduction of the AgCl. This process still is not understood very well.

 

With respect to skin, I think that in practice there is no difference. Any person, who gets AgNO3 or any soluble Ag-salt on his/her skin will get black stains, regardless of presence of salt, or presence of light. Of course, there might be differences in speed of reaction, but in all cases, the reaction is fast and irreversible. Even if no stain can be observed and then the AgNO3 is rinsed off, it will stain lateron, due to Ag(+) ions absorbed by your skin and reacting anyway.

 

So, summarizing: With paper indeed the use of NaCl or NaBr has stromng influence on the speed of oxidation. With skin I think that there will be some effect also, but this effect is irrelevant for the people, who have the stains. The stains appear anyway.

[YT2095]

Hmmm... I think I can see where the misunderstang`s occured, the Metal vs Ion should have been a dead giveaway actualy

it`s happened before also, basicly it`s the old Reactivity vs Electode potential cross.

silvers Electronic potential is 1.98v (very low, infact the lowest I have listed as a pure metal) and yet silver itself is quite inert.

by contrast we have Lithium with -3.03v electronic potential (the highest listed here) and yet lithium is the least reactive when compared to something like Sodium who`s potential is only -2.7).

 

if this isn`t the case here, then I`m at a total loss as to what is

 

edit: reading back at my post, a Lithium / Silver battery should have a pd of about 5 volts! I`m might just try this as a next Battery experiment when bored

[woelen]

The redox potential for silver only is 0.80 volts, not 1.98. Have a look at http://www.wissensdrang.com/auf1rp.htm for some common half reactions.

 

But still, your cell would make about 3.8 volts. Probably a little less, because of resistive losses.

 

The misunderstanding in your reasoning indeed was between the metal and the ion. The ion really is totally different.

 

The reason why lithium is less reactive than sodium and potassium also has to do with properties of lithium compounds. Lithium hydroxide for instance is not very soluble in water, so this clogs up a free path of water to the lithium metal.

[YT2095]

it`s 0.8 for the metal but the Ag(2+) ions are 1.98v, and we were discussing ions and their oxidation properties.

 

http://72.14.207.104/search?q=cache:dqffWLkSCY4J:www.a-levelchemistry.co.uk/AQA%2520A2%2520Chemistry/14.3%2520Redox%2520Equilibria/Topic%252014.3%2520notes.doc+%22standard+electrode+potential%22+%22ag2%2B%22+1.98&hl=en&ct=clnk&cd=2

 

the interesting bits are highlighted in Green