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I would figure approximately
1.22ml 68% HNO3 + 1.22ml H2O for a gram of silver
3.5ml 68% HNO3 + 3.5ml H2O for a gram of copper (or base metal)
even more, water will save on nitric consumption due to loss as NOx gas, a small addition of 3% H2O2 can also assist...
Sterling silver 92.5% silver 7.5% copper
Coin silver 90% silver and 10% copper
1.22ml 68% HNO3 + 1.22ml H2O for a gram of silver
3.5ml 68% HNO3 + 3.5ml H2O for a gram of copper (or base metal)
even more, water will save on nitric consumption due to loss as NOx gas, a small addition of 3% H2O2 can also assist...
Sterling silver 92.5% silver 7.5% copper
Coin silver 90% silver and 10% copper
It is also helpful to look at the information above, or in other ways.
From the information above we can figure that it would take about 1 gram of copper metal to cement about 3 grams or more of silver metal from an ionic silver nitrate solution.
From the information above we can figure that it would take about 1 gram of copper metal to cement about 3 grams or more of silver metal from an ionic silver nitrate solution.
Exactly how much you need is impossible to say, it depends on your setup.
There are two different reactions that can occur and it depends on the acid concentration among other things.
https://www.youtube.com/watch?v=U8v2zbUYBgw
Göran
There are two different reactions that can occur and it depends on the acid concentration among other things.
https://www.youtube.com/watch?v=U8v2zbUYBgw
Göran
g_axelsson said:
In the video he explains why a hot solution works faster than a cold solution but now I have another question...of course. If I understand that explanation right, it also explains why a hot solution will hold more metals than a cold solution. And why, when a hot solution cools it drops out some metals as a balancing act to hold the metal volume of a cold solution. It is that anywhere near close?
I hope that makes sense, as I am struggling to explain it.
Martijn
Well-known member
Yes, and the more you cool it down, the more will fall out or crystalize out.
Cool and dilute solutions can slow the process but will dissolve more silver.
The cooler the solution the more gases it can hold, the slower the nitric decomposes to form the gases that dissolve the silver or copper...
Excess water helps to keep the NO2 gas (red deadly cloud of gas) from leaving the solution as easy, the water helps to reform the gas back into HNO2 and HNO3 which will dissolve more silver ...
NO gas is not water-soluble it is clear until it gets oxygen from the air and changes to NO2 gas (red gas)
A small amount of H2O2 will help to convert the NO gas into NO2 and thus into HNO2 and HNO3 in solution to dissolve a little more silver...
Highly concentrated solutions of nitric do not work as well. The reaction can be very slow to begin (as the nitric decomposes to be able to dissolve the silver) and become vigorous with high losses of nitric due to NOx evolution...
Heating can speed the reactions but also can force more gasses from the solution...
In the video, he was making silver nitrate crystals, the concentration and his process was different from what we do when recovering silver ...
silver nitrate is fairly soluble and when we dilute our 70% nitric with equal volumes of water to dissolve silver in the recovery process, we will not crystalize out AgNO3 with normal cooling of the solution the crystals will not form without a whole lot of evaporation of the solution to dryness...
The cooler the solution the more gases it can hold, the slower the nitric decomposes to form the gases that dissolve the silver or copper...
Excess water helps to keep the NO2 gas (red deadly cloud of gas) from leaving the solution as easy, the water helps to reform the gas back into HNO2 and HNO3 which will dissolve more silver ...
NO gas is not water-soluble it is clear until it gets oxygen from the air and changes to NO2 gas (red gas)
A small amount of H2O2 will help to convert the NO gas into NO2 and thus into HNO2 and HNO3 in solution to dissolve a little more silver...
Highly concentrated solutions of nitric do not work as well. The reaction can be very slow to begin (as the nitric decomposes to be able to dissolve the silver) and become vigorous with high losses of nitric due to NOx evolution...
Heating can speed the reactions but also can force more gasses from the solution...
In the video, he was making silver nitrate crystals, the concentration and his process was different from what we do when recovering silver ...
silver nitrate is fairly soluble and when we dilute our 70% nitric with equal volumes of water to dissolve silver in the recovery process, we will not crystalize out AgNO3 with normal cooling of the solution the crystals will not form without a whole lot of evaporation of the solution to dryness...
Solubility varies with temperature, different amount depending on what substance and what liquid we have. How much it changes with temperature is also depending on what substance.
We can use that to our advantage, for example when we chill our nitric acid when making it from nitrates and sulfuric acid.
Nurdrage have made a lot of good videos. Another good source for chemical videos is Nile Red.
Here is one which he shows crystallization as a way of purifying certain chemicals.
https://www.youtube.com/watch?v=T2Z8tFXYpI8
Göran
We can use that to our advantage, for example when we chill our nitric acid when making it from nitrates and sulfuric acid.
Nurdrage have made a lot of good videos. Another good source for chemical videos is Nile Red.
Here is one which he shows crystallization as a way of purifying certain chemicals.
https://www.youtube.com/watch?v=T2Z8tFXYpI8
Göran
Approximate solubility in grams per 100ml H2O of some nitrate salts
salt ------------- 0 degC------20degC ------100degC
AgNO3 ------------122g---------216g----------733g
Cu(NO3)2----------84g----------125g---------247g
Zn(NO3)2------------98g---------128g----------xxx
NH4NO3-------------118g----------192g-----------871g
Pb(NO3)2------------37g------------54g-----------133g
Ni(NO3)2-------------79g-----------94g-------------170g
KNO3------------------13g-------------31g----------246g
NaNO3----------------73g-------------87g-----------180g
at 0 degC a nitrate solution can hold 122g of silver nitrate.
at 0 degC a nitrate solution can hold 13g of potassium nitrate.
at freezing potassium nitrate will precipitate out before the silver, or at any temperature, silver nitrate is much more soluble than potassium nitrate, in fact beside ammonium nitrate, silver nitrate looks to be much more soluble than the other metal nitrates above at most any temperature, a fairly insoluble salt like barrium nitrates are not very soluble at 0 degC a little over 4grams are soluble in 100ml H2O
salt ------------- 0 degC------20degC ------100degC
AgNO3 ------------122g---------216g----------733g
Cu(NO3)2----------84g----------125g---------247g
Zn(NO3)2------------98g---------128g----------xxx
NH4NO3-------------118g----------192g-----------871g
Pb(NO3)2------------37g------------54g-----------133g
Ni(NO3)2-------------79g-----------94g-------------170g
KNO3------------------13g-------------31g----------246g
NaNO3----------------73g-------------87g-----------180g
at 0 degC a nitrate solution can hold 122g of silver nitrate.
at 0 degC a nitrate solution can hold 13g of potassium nitrate.
at freezing potassium nitrate will precipitate out before the silver, or at any temperature, silver nitrate is much more soluble than potassium nitrate, in fact beside ammonium nitrate, silver nitrate looks to be much more soluble than the other metal nitrates above at most any temperature, a fairly insoluble salt like barrium nitrates are not very soluble at 0 degC a little over 4grams are soluble in 100ml H2O
AgNO3 solubility
https://saltlakemetals.com/solubility_of_silver_nitrate/
https://saltlakemetals.com/solubility_of_silver_nitrate/
