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CHRIS25
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Silver Nitrate Calculation/maths check
Hi, yes it's me again and when I have sufficient confidence in my own rusty brain I will stop asking people to check. Please could you have a look at
this:
Ag+2HNO3=Ag(NO3)+NO2+H2O
107.8+126=169.87+46+18
But for 30% nitric acid:
357mls instead of 126mls.
I have 11.4g of silver to waste. so therefore:
11.4/107.8 x 100 = 10.6%. 10.6% of 357mls = 37.8mls
So for 11.4g of silver I should use 37.8mls of 30% HNO3. The theoretical yield being 17g of Ag(NO3). But I have a feeling this last bit is wrong, I
simply did 10.6% of 169.87.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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vmelkon
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If you start with 11.4 g of Ag.
Convert to moles
11.4 g / 107.8 g/mol = 0.1085343 mol of Ag
You will need 2 times the amount in HNO3
0.1085343 mol * 2 = 0.21706864 mol of HNO3
Convert the above to grams
0.21706864 mol * 63 g/mol = 13.67532432 g of HNO3
If 30% HNO3 means 30 g HNO3 per 100 g.
13.67532432 g / 30 g * 100 g = 45.5844144 g of your 30% HNO3 is needed.
It depends on what 30% HNO3 means. Is it in terms of weight or volume?
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CHRIS25
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Hi, well I have no idea because the Bottle simply says 30%, no w/v or vol or weight words anywhere. Thankyou for the above I'm going to have to go
through that again. While you are here? Do you think you could tell me if I have this right: Wanting to make 5% citric acid from the solid. I
actually took 5% of 72g because 72g is the solubility in 100ml water meaning that that is the concentration. So i added 3.6g per 100ml water. Is
this the correct procedure? I am not needing gram for gram accuracy, but acceptable accuracy say +/- 5%, which I know is huge in tiny quantities, but
I am dealing in half litres most of the time.. (since this is all to do with photography). Thankyou.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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kavu
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A 5 % mass-volume solution (the common one) contains 5 g of material per every 100 ml of solvent.
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vmelkon
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There is a large variety of concentration expressions
http://en.wikipedia.org/wiki/Concentration
I was assuming your HNO3 30% was using mass fraction.
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CHRIS25
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Quote: Originally posted by kavu  | | A 5 % mass-volume solution (the common one) contains 5 g of material per every 100 ml of solvent. |
Oh! But
what if a concentrated solution is say 4.5g in 100ml? Then surely 5g is certainly not 5% strength. 5% acidity means 5% concentrate and each acid has
a diifferent weight of dry matter (gas/solid) to make it concentrated, hence logic, at least my logic suggests that the initial amount of dry matter
will vary considerably for each acid, different weights but all 5%?
vmelkon: "There is a large variety of concentration expressions" Thankyou for that pointer.
[Edited on 11-10-2012 by CHRIS25]
[Edited on 11-10-2012 by CHRIS25]
[Edited on 11-10-2012 by CHRIS25]
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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kavu
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| Quote: Originally posted by CHRIS25 | | Oh! But what if a concentrated solution is say 4.5g in 100ml? Then surely 5g is certainly not 5% strength. 5% acidity means 5% concentrate and
each acid has a diifferent weight of dry matter (gas/solid) to make it concentrated, hence logic, at least my logic suggests that the initial amount
of dry matter will vary considerably for each acid, different weights but all 5%? |
Then you can't make a 5% solution and that's it. This is why molarity is the best way of presenting concentrations for stoichiometric use.
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arsphenamine
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Given the abundance of nitric acid density tables indexed by %weight and temperature, I'm betting that a %HNO3 concentration is a
weight-per-weight figure.
This isn't an analytical lab prep, so most values get only 3 or 4 sig figs.
30% %HNO3 (aq) has a density(20C) of 1.18 g/ml.
1.18 g/ml = 1180 g/litre
30% of it is HNO3 by weight, or 354 grams/litre
HNO3 Formula Weight is 63 g/mol (neglecting isotopes).
30% = (354/63) moles/litre = ~5.62 Molar or 5.62 M
11.4g Ag is 11.4/107.9 or 0.105 moles.
In a simple world in which ions at all solution strengths have a 1.0 α activity coefficient, you'd need (2 * 0.105) = 0.21 moles of
HNO3 to dissolve that silver.
moles / (moles/litre) = litres, so 0.21 / 5.62 is 0.03737 litres or ~37.4 ml.
37.4 ml 30% HNO3 is the bare minimum needed to dissolve 11.4 g silver.
At a 1.18 g/ml density, that volume weighs 44.1 grams.
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CHRIS25
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Thankyou I see that I at least had the original quantities correct though by a different means. However I will have to go through your maths and that
of vmelkon's and see why you both differ. At least I learn.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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arsphenamine
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| Quote: Originally posted by CHRIS25 | | Thankyou I see that I at least had the original quantities correct though by a different means. However I will have to go through your maths and that
of vmelkon's and see why you both differ. At least I learn. |
vmelkon made a few small transcription errors.
My calculations are the One, the Truth, the Infallible (note capitals).
Look on my works, Ye Mighty, and wonder, "...like, what the fuck?"
More seriously, the crucial bits are how 30% is a weight-per-weight spec and the HNO3 density is 1.18 g/ml or 1.18 kg/litre. It all flows cleanly
after that.
-hizself
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CHRIS25
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Phenamine - thankyou, "More seriously, the crucial bits are how 30% is a weight-per-weight spec and the HNO3 density is 1.18 g/ml or 1.18 kg/litre. It
all flows cleanly after that." good to learn this.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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ElizabethGreene
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Hello.
With the disclaimer that I am an utter noob, isn't the correct procedure to titrate the nitric acid? This gives you a solution with a known
moles/liter value? Or do I not understand the function of titration?
-elizabeth
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ElizabethGreene
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Related subject question: When the silver is dissolving in the nitric acid solution, it liberates NO and NO2. Could those gases be drawn through
water to reduce the hazardous waste and reclaim some of the Nitric Acid?
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tetrahedron
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sure, you would recover some nitric acid that way, but only the NO2 hydrolyzes producing nitric acid (and more NO), so make sure you add
enough air to convert all NO to NO2, and find a way to contain the NO.
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CHRIS25
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Confirming Silver or Silver nitrate method for production
I synthesized the silver alloy to a solid piece of 6 gm worth of silver as a lump. To check that it was free from copper I re-dissolved it in 20ml
of 30% HNO3. The solution is perfectly clear, no perceptible blue at all, so job well done. I now have a choice, I either boil the whole solution to
leave me with solid silver again, or allow the solution to slowly evaporate to leave me with Silver Nitrate crystals. Is this correct? The boiling
away idea because as I have read on this site so often, that the nitrate decomposes quite easily at high temperatures above the 70c mark, plus the
water will obviously disappear.
[Edited on 20-10-2012 by CHRIS25]
[Edited on 20-10-2012 by CHRIS25]
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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kristofvagyok
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| Quote: Originally posted by CHRIS25 | | I have read on this site so often, that the nitrate decomposes quite easily at high temperatures above the 70c mark, plus the water will obviously
disappear. |
Silver nitrate is quite stable, it is also meltable (mp. above 200 according to my memories), it will decompose on lower temperature in presence of
organic impurities.
I have a blog where I post my pictures from my work: http://labphoto.tumblr.com/
-Pictures from chemistry, check it out(:
"You can’t become a chemist and expect to live forever." |
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CHRIS25
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from 11g to 6g to 4g.....So glad I didn't start with Gold
I startted off with 11.7g of silver alloy, after the first synthesis I ended up with 6.1g. After re-dissolving and evaporating I have 4.1g of silver
nitrate. This is not good chemistry
Allowing for the fact that my silver might well have been 725 and not 925, (there were only hallmarks, no numbers) that would mean that I started with
8.5g of silver. So I lost 2.4 along the way. Then I lost another 4 during evaporation??? I'm lost. Can someone help please before I wreck my
biggest chunks of silver.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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vmelkon
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No, you don't lose anything during evaporation. You probably weighted your silver nitrate and it was humid and then you weight it again, it is going
to be lighter.
I'm just guessing here. You don't give much details about what you did.
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CHRIS25
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Basically, 11.4g silver alloy dissolved in 37mls HNO3. Via copper displacement I then filtered the residue of silver mud with distilled water 3 times
and collected the mud. While wet I blow torched until there was only white residue left, all the brown mud dissappeared. I then blow torched this
whitish mud on a pre-charcoaled piece of wood with a much higher temperature at 1200c. I obtained a nice piec of silver at around 6.1g. I then
dissolved this in HNO3 looking for traces of copper impurities. The liquid was clear. I then allowed this to cool and evaporate naturally and
weighed it while it was just a little hydrated, not fully dry. It is only 4g. This is a brief overview, I think something is wrong along the way, I
feel I should not have lost 2g from the silver solid to the silver nitrate. If I lost anything at the first stage, when it originally went into the
HNO3, before seperation, then I know probably when this happened, I think at the filtration stage, maybe lost a gram or two there, I know why. But
coming from 6g solid silver to 4 gram silver nitrate seems odd?
I think I may have one explanation: When it first cooled there was still the solution, I picked it up and after a few seconds of shaking the beaker
the crystals formed very quickly, quite a lot and the liquid seemed to dissappear. After leaving this for half a day, half of the crystals
dissappeared and the solution re-appeared. I then did something that I think I should not have, I assumed, without thinking, that this was all there
was and poured the solution away to leave only the precipitated crystals, which after about a few hours seemed to settle and diminish a little?? This
last observation is purely subjective. I was wondering whether or not he silver nitrate would re-dissolve partly? And that is where I lost my 2g??
[Edited on 21-10-2012 by CHRIS25]
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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vmelkon
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If you go from 11.4 g (silver alloy) to 6.1 g (pure silver) then that means 6.1/11.4 = 53% which means you still had silver nitrate in your solution.
The problem with displacement reactions is that when you place you stick of metal in there, it gets covered with your second metal and the reaction
slows down a lot (or stops).
I don't have experience with your case but from what I have seen, you can shake the copper and the silver crystals fall off down to the bottom of the
solution and new crystals begin to grow.
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kristofvagyok
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So, let's see an old method from book written in 1954 named "pharmaceutics and their preparation".
The silver is granulated by the following: they melt it and pour it in large amount of water with stirring (this is not so easy, so please don't try
it at home). These granulates (15kg) is placed in a large bath containing 20liter of 50% nitric acid. After the reaction happens, under circa 6 hour
(beware of foaming out), they turn up the heating and boil it for a while.
When nothing happens, the upper layer is poured to another flask and the remaining silver is washed with large amount of water.
The discarded solution what contains the silver is boiled till dryness and heated further. The AgNO3 will melt and the Cu-nitrate will decompose. This
will happen fully at 250 Celsius. The resulting blackish stuff is added to a lot water, stirred until no more dissolves and the remaining CuO is
decanted, the water clear solution is evaporated to dryness to get the remaining AgNO3.
Good luck.
I have a blog where I post my pictures from my work: http://labphoto.tumblr.com/
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cyanureeves
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add salt to the left over silver nitrate solution and get your silver chloride then reduce it with muriatic acid and zinc penny cores.
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CHRIS25
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OK ok ok guys stop. First, the silver chloride method sucks. I have read about it and it's an unnecessary step. Secondly, vmelkon and kristof I was
past the first stage, I know where I might have lost the first part, in the initial seperation as previously explained. I am more concerned to know
whether or how or why or what with regards to the loss of two grams from the dissolving of the solid PURE silver to the now dry silver nitrate that is
sitting on my desk.
And Kristof:======== When nothing happens, the upper layer is poured to another flask and the remaining silver is washed with large amount of water.
The discarded solution what contains the silver is boiled till dryness and heated further. ====== This is very bad English from 1953, it is
ambiguous. The words "discarded" and "upper layer" refer to the same liquid? it seems here that both the discarded solution (or is this the the
upper layer?) and the upper layer contain silver which makes no sense. As I said this is confusingly written.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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kristofvagyok
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| Quote: Originally posted by CHRIS25 | | The words "discarded" and "upper layer" refer to the same liquid? it seems here that both the discarded solution (or is this the the upper layer?)
and the upper layer contain silver which makes no sense. As I said this is confusingly written. |
Yes, they should have meant the same.
I have a blog where I post my pictures from my work: http://labphoto.tumblr.com/
-Pictures from chemistry, check it out(:
"You can’t become a chemist and expect to live forever." |
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CHRIS25
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Oh well. Anyway, I'm going to make some more silver nitrate and then buy an ounze coin. It really works out cheaper than buying silver nitrate from
a supplier. I stained my fingers! I only touched the sides of the porcelain dish when I was fiddling - lesson learned.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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