Growing large silver crystals
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An elderly friend, now long departed, grew them in an enclosed container in which he had a pointed electrode on one end, with a small anode of silver attached to the other end. I never saw his setup----but we discussed it at length. Unfortunately, he died back in '84, so my memory has dimmed considerably.
Silver will grow crystals if you keep the purity of electrolyte high and limit it's ability to plate out of solution. On rare occasions, a spot in my silver cell would grow a few that were large enough to save, although I don't recall that I saved any of them aside from maybe one. They were not large, perhaps fingernail size at best, but my objective was to purify silver, not to grow large crystals.
Incidentally, when you operate a silver cell, it becomes obvious that the silver grows as crystals, albeit small ones. It appears to me that if you limit area, you'll get nothing but large crystals, but I don't know that.
Do use pure silver, no copper. Copper, from my experience, tends to form soft crystals that won't grow large in size. The few relatively large crystals that I grew always came early in the operation, before the copper level of my electrolyte increased. I used silver crystal to make my electrolyte, adding no copper. As the level of copper increased, the nature of the crystal changed considerably, finally growing nothing but long strands of silver threads, very soft. Shortly thereafter, copper would start to co-deposit with the silver. On such occasions, I'd simply place the once refined silver back in the basket and part it a second time, using new electrolyte and an anode that was placed on top to insure good electrical contact.
Hope some of this helps.
Harold
Silver will grow crystals if you keep the purity of electrolyte high and limit it's ability to plate out of solution. On rare occasions, a spot in my silver cell would grow a few that were large enough to save, although I don't recall that I saved any of them aside from maybe one. They were not large, perhaps fingernail size at best, but my objective was to purify silver, not to grow large crystals.
Incidentally, when you operate a silver cell, it becomes obvious that the silver grows as crystals, albeit small ones. It appears to me that if you limit area, you'll get nothing but large crystals, but I don't know that.
Do use pure silver, no copper. Copper, from my experience, tends to form soft crystals that won't grow large in size. The few relatively large crystals that I grew always came early in the operation, before the copper level of my electrolyte increased. I used silver crystal to make my electrolyte, adding no copper. As the level of copper increased, the nature of the crystal changed considerably, finally growing nothing but long strands of silver threads, very soft. Shortly thereafter, copper would start to co-deposit with the silver. On such occasions, I'd simply place the once refined silver back in the basket and part it a second time, using new electrolyte and an anode that was placed on top to insure good electrical contact.
Hope some of this helps.
Harold
Thanks
Even if it’s not a recipe, it certainly points in the right direction.
I’ve made a relatively primitive experiment, just a fine silver wire and a bar of (relatively) fine silver (chloride precipitation, then reduced with zinc) hanging in ½ a litre of silver nitrate solution (dissolving 30 grams of copper cemented silver in 30 mL of nitric acid + 30 mL of water, then diluted to 500 mL with distilled water).
(Some copper must have remained, the solution was light green)
Running at approx 4 amps, the silver precipitates as a relatively fine powder when the solution is cold, changing to long feathery crystals as it warms. I guess they are less than half a millimetre wide, and up to 15 mm long before dropping to the bottom.
High voltage seemed to encourage “strandy” growth.
Guess I’ll have to refine some more, do it carefully, and then try it clean, slow and at only a couple of volts.
Even if it’s not a recipe, it certainly points in the right direction.
I’ve made a relatively primitive experiment, just a fine silver wire and a bar of (relatively) fine silver (chloride precipitation, then reduced with zinc) hanging in ½ a litre of silver nitrate solution (dissolving 30 grams of copper cemented silver in 30 mL of nitric acid + 30 mL of water, then diluted to 500 mL with distilled water).
(Some copper must have remained, the solution was light green)
Running at approx 4 amps, the silver precipitates as a relatively fine powder when the solution is cold, changing to long feathery crystals as it warms. I guess they are less than half a millimetre wide, and up to 15 mm long before dropping to the bottom.
High voltage seemed to encourage “strandy” growth.
Guess I’ll have to refine some more, do it carefully, and then try it clean, slow and at only a couple of volts.
Well, I'm going to try it one of these days. (Just have to get my power supply available from another experiment first)
A thin solution of silver nitrate (chemically pure), a bar of fine silver and an isolated silver wire, with just the tip exposed.
Sealed in a flask to avoid loosing water and introducing dirt.
Low temperature, approx 10°C
Low concentration, 0.25M, 0.5M as a reserve if nothing happens.
Low voltage, just 1½-2 Volts
Loooong time, I guess
Apparatus as shown below.
(I know that this is "playing", but most of us are doing just that anyway)
A thin solution of silver nitrate (chemically pure), a bar of fine silver and an isolated silver wire, with just the tip exposed.
Sealed in a flask to avoid loosing water and introducing dirt.
Low temperature, approx 10°C
Low concentration, 0.25M, 0.5M as a reserve if nothing happens.
Low voltage, just 1½-2 Volts
Loooong time, I guess
Apparatus as shown below.
(I know that this is "playing", but most of us are doing just that anyway)
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My friend's container was flat, which is conducive to supporting large crystals. Electrodes were on opposing ends, near the bottom. The container was relatively shallow, and made of plastic as I recall.
The one thing I remember is that the cathode was just a point---so the silver had no option but to form in an isolated place. You might give that some thought. Anode and cathode spacing, along with electrolyte concentration, will play a role in voltage. I agree, low amperage, but do experiment. I'm not convinced you want the concentration particularly low. I used 30 troy ounces of silver in my electrolyte for my parting cell, which held about 8 liters of solution. Hope some of this is helpful. It's been years since I last did any of this stuff.
Harold
The one thing I remember is that the cathode was just a point---so the silver had no option but to form in an isolated place. You might give that some thought. Anode and cathode spacing, along with electrolyte concentration, will play a role in voltage. I agree, low amperage, but do experiment. I'm not convinced you want the concentration particularly low. I used 30 troy ounces of silver in my electrolyte for my parting cell, which held about 8 liters of solution. Hope some of this is helpful. It's been years since I last did any of this stuff.
Harold
Great, I'll try that too! (It makes sense, and it will be quite easy to do)Harold_V said:
Harold_V said:
So is mine. The L-shaped part is isolated, first by a thick layer (black), then by a thinner (dark green), only at the wery tip is the silver exposed by ½ a millimeter.
Harold_V said:
Wow, that's 114 grams silver pr. litre :shock: equalling 181 grams of silver nitrate.
The solubility of silver nitrate is 170 g/100 mL at 10 °C and 257 g/100 mL at 25°C. Practically a saturated solution.
My fault, by the way, I used the wrong argument for low concentration.
Crystals will form when a solution is super-saturated. The normal way to control that reaction when growing large crystals, is to just supersaturate it slightly, normally by using a weak solution or changing the temperature.
But here, the supersaturation is caused by current, not concentration.
Thanks, you really are a great help. (Help from people who have "been there, seen it, done it" is very valuable!)
Regards
Peter
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Very good! I couldn't tell that from the pic. You're on the right track, for sure.peter i said:
Heh! I'd dissolve that 30 ounces in a 4,000 ml beaker, using a liter of nitric and adding enough distilled water to get it going, then apply heat, taking it to boiling. After it had boiled for a prolonged period of time the vast majority of the silver was gone, although if there were traces, they were simply included in the cell with the electrolyte. I used silver crystals from the cell to make new electrolyte, so it made no difference.
Interestingly, as the solution cooled, unless I added more distilled water, it formed huge crystals of silver nitrate. Yep-it was damned well saturated!
I wish I could have provided more guidance. Growing crystals was not my concern, although some grew of their own accord, as I suggested. Had I held greater interest, I'd have learned more from my old friend. Too late now, so I'm relying on you! Please give us all a report on your success, and don't hesitate to show us some pics. They're always welcome.
By the way, my friend grew a few crystals that bordered on ten troy ounces. He really enjoyed good success.
Harold
First try:
2 grams of analytical grade silver nitrate dissolved in 15 mL of distilled water.
The tray is a polystyrene "specimen box" (shown without the lid in the photo).
Fine silver wires are pushed through the ends and secured with hot melt glue.
Power supply was a large 1½ Volt Duracell.
It failed misserably. In just one hour, a long strand of crystals grew from one end to the other.
:evil:
Next try will be from a dilute solution (diluting the present solution with a factor of 5, I guess)
2 grams of analytical grade silver nitrate dissolved in 15 mL of distilled water.
The tray is a polystyrene "specimen box" (shown without the lid in the photo).
Fine silver wires are pushed through the ends and secured with hot melt glue.
Power supply was a large 1½ Volt Duracell.
It failed misserably. In just one hour, a long strand of crystals grew from one end to the other.
:evil:
Next try will be from a dilute solution (diluting the present solution with a factor of 5, I guess)
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Pete,
Looks like you had success to me! GSP once mentioned using motion to keep the crystals from shorting out your rig. Maybe if you just rock the dish every once in a while you can break the strand and form granules of pure silver.
If you want big bulky crystals you may try putting a resistor inline with the positive lead to limit the current so it doesn't make a B-Line to the negative lead. Another possibility would be to put a partition in the cell to stop the progress of the crystals across the cell.
I think your 'mini-cell' is awesome!
Steve
Looks like you had success to me! GSP once mentioned using motion to keep the crystals from shorting out your rig. Maybe if you just rock the dish every once in a while you can break the strand and form granules of pure silver.
If you want big bulky crystals you may try putting a resistor inline with the positive lead to limit the current so it doesn't make a B-Line to the negative lead. Another possibility would be to put a partition in the cell to stop the progress of the crystals across the cell.
I think your 'mini-cell' is awesome!
Steve
A
Anonymous
Guest
cut that crystal halfway leaving one end attached, then continue growing,
and cutting out the short, eventually the half your saving would be quite massive.
I think that could work.
and cutting out the short, eventually the half your saving would be quite massive.
I think that could work.
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I'm of the opinion that your voltage is too high (for conditions). I ran my parting cell at approximately 3 volts, but the spacing, anode to cathode, was about 3".
A resistor isn't a bad place to start, or achieving a greater space between the two poles might be helpful. It will be interesting to see if a lower concentration will work, too. The electrolyte will likely seek its own level once the cell operates to your satisfaction. Could be a lower concentration would be helpful---it certainly should change conductivity.
What you accomplished is very pretty! You're on the right track.
Harold
A resistor isn't a bad place to start, or achieving a greater space between the two poles might be helpful. It will be interesting to see if a lower concentration will work, too. The electrolyte will likely seek its own level once the cell operates to your satisfaction. Could be a lower concentration would be helpful---it certainly should change conductivity.
What you accomplished is very pretty! You're on the right track.
Harold
Thanks guys!
Test number two used a 1:4 dilution of the ”2g @ 15 mL” solution, but yielded the same result.
The crystals grew 20 mm in a little more than an hour. Even if it doesn’t work the way I intended, it’s a nice chemical demonstration. Placed in a Petri dish on an overhead projector, it could grow throughout a lecture (a modern projector with camera would give cool pictures).
You’ve given three suggestions:
- Pruning, to just keep a single crystal growing
- Rocking to break up the crystals
- Changing the power supply
I’ll start with the power. This goes well with the observation, that high voltage gives a strandy growth.
It’s easy to do, and easy to control (and will need less attention on my part). A variable resistor should do the trick.
But should it be hooked up as a rheostat, limiting the current, or as a potentiometer, limiting the voltage?
If Harold's guess is right, it's the pot-meter solution.
( http://www.kpsec.freeuk.com/components/vres.htm just a a reminder to myself. I'm a chemist, not an electronics guy :shock: )
I recently scrounged a lab power-supply. After restoring it (ie: washing out the chemical deposits inside it, yuck! Beating out the dents in the cabinet and replacing the proken connectors), I’m exited to see if it will work when I plug it in or if I’ll just turn out the light in the neighbourhood :?
It may come in handy, once the pilot study is done.
This is my ”micro-cell” by the way. My “mini-cell” is a 500 mL cell made from a rectangular glass vase and some Perspex (an excuse for experimenting on the welding of Perspex with chloroform
It just sits on the workshop table, growing larger crystal than the micro-cell!
Test number two used a 1:4 dilution of the ”2g @ 15 mL” solution, but yielded the same result.
The crystals grew 20 mm in a little more than an hour. Even if it doesn’t work the way I intended, it’s a nice chemical demonstration. Placed in a Petri dish on an overhead projector, it could grow throughout a lecture (a modern projector with camera would give cool pictures).
You’ve given three suggestions:
- Pruning, to just keep a single crystal growing
- Rocking to break up the crystals
- Changing the power supply
I’ll start with the power. This goes well with the observation, that high voltage gives a strandy growth.
It’s easy to do, and easy to control (and will need less attention on my part). A variable resistor should do the trick.
But should it be hooked up as a rheostat, limiting the current, or as a potentiometer, limiting the voltage?
If Harold's guess is right, it's the pot-meter solution.
( http://www.kpsec.freeuk.com/components/vres.htm just a a reminder to myself. I'm a chemist, not an electronics guy :shock: )
I recently scrounged a lab power-supply. After restoring it (ie: washing out the chemical deposits inside it, yuck! Beating out the dents in the cabinet and replacing the proken connectors), I’m exited to see if it will work when I plug it in or if I’ll just turn out the light in the neighbourhood :?
It may come in handy, once the pilot study is done.
This is my ”micro-cell” by the way. My “mini-cell” is a 500 mL cell made from a rectangular glass vase and some Perspex (an excuse for experimenting on the welding of Perspex with chloroform
It just sits on the workshop table, growing larger crystal than the micro-cell!
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The reason I suggested voltage control is that's how I managed to run my cell for a prolonged period of time without shorting. It ran 24/7 for weeks on end, until I'd processed all the silver I had at hand. I'd then accumulate again until I needed to refine, then start over.
It's been years since I ran a cell, but I recall that the recommended amperage per sq. ft. was something like 15 amps. What ever voltage it took to achieve that amperage is what I used at first, having a Variac in my power supply (home built). I simply controlled the voltage fed to the transformer. The first day of operation kept me jumping--so I reduced the voltage, which had a corresponding decrease in the amperage. Seems I ran it at about 12 amps/ft, but I'm not sure. Could be I have the information saved, which I'll check when time allows.
I screwed with the voltage until I found a place where it produced nicely, producing more coarse crystals than hair or wire, and then I ran it there. I never went back to the higher voltage, finding it was to my benefit to slow it down and produce coarser crystal. I'd have to get up during the night to knock it down (my lab was at home), but only once. I ran it that way constantly, which actually proved to be quite adequate. It allowed me to pursue my other duties, checking on the cell only about every 3 or 4 hours. As slow as it was, I'd still turn about 100 ounces in a day or a little longer. Not as bad as it may sound, at least for a small operation.
Bottom line----I truly believe that lower voltage will help. Keep us posted!
Harold
It's been years since I ran a cell, but I recall that the recommended amperage per sq. ft. was something like 15 amps. What ever voltage it took to achieve that amperage is what I used at first, having a Variac in my power supply (home built). I simply controlled the voltage fed to the transformer. The first day of operation kept me jumping--so I reduced the voltage, which had a corresponding decrease in the amperage. Seems I ran it at about 12 amps/ft, but I'm not sure. Could be I have the information saved, which I'll check when time allows.
I screwed with the voltage until I found a place where it produced nicely, producing more coarse crystals than hair or wire, and then I ran it there. I never went back to the higher voltage, finding it was to my benefit to slow it down and produce coarser crystal. I'd have to get up during the night to knock it down (my lab was at home), but only once. I ran it that way constantly, which actually proved to be quite adequate. It allowed me to pursue my other duties, checking on the cell only about every 3 or 4 hours. As slow as it was, I'd still turn about 100 ounces in a day or a little longer. Not as bad as it may sound, at least for a small operation.
Bottom line----I truly believe that lower voltage will help. Keep us posted!
Harold
The lab-supply works like a charm! (unbelieveable regarding the punishment it had taken! White crystalline crusts and abominable brown gunk inside. Add to that a couple of good dents in the cabinet, circuitboards dangling loose and a nut that should have secured the cabinet gone AWOL. But she has a good home now 8) )
Experiment #3 is cooking
15 mL micro-cell
The dilute silver nitrate from #2,
0,48 Volts,
current limit set at ½ Ampere (just to keep it cool if it shorts out).
regards
Peter
Experiment #3 is cooking
15 mL micro-cell
The dilute silver nitrate from #2,
0,48 Volts,
current limit set at ½ Ampere (just to keep it cool if it shorts out).
regards
Peter
A
Anonymous
Guest
What about a pulsed voltage like from a cell phone charger.
peter i said:Experiment #3 is cooking
15 mL micro-cell
The dilute silver nitrate from #2,
0,48 Volts,
current limit set at ½ Ampere (just to keep it cool if it shorts out).
No "discrete single crystal synthesis" yet, but a small dense cluster of larger crystals. The largest is coming close to 5mm.
It looks promising, and will be allowed to run for another week.
I'm considering using a small single-crystal as a seed for the next run, to have a single well defined crystal lattice to start from.
Experiment #3 just went on in the same substrate as #1 and #2, and there were plenty of small crystals remaining (to act as multiple seeds).
austexjwlry
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Peter i,
I had 8 filters full to the brim of clean gold from deplated items and some gold already recovered from inquarted jewelry items, approx. 20 grams to a filter dissolving in some AR outside in a coffee pot. After it quit fuming I put it and the plastic bowl it was in inside my storeroom to let it finish working while I did other chores.
My wife of 18 yrs whom I still love very much was putting a couple bags of aluminum cans into the same storeroom but didn't like the smell so she threw the bags of cans onto her pile from the open door! One of them fell into my bowl and coffee pot spilling the contents onto the pressboard floor!
She put on my gloves and started cleaning up the spill with paper towells. she is very mildly asthmatic anyway, so we ended up going to the E.R., 4 days later we were able to come home. Watching her suffer was the most traumatic ordeal I've ever been through!
I cleaned up what I could with paper towels using a spray bottle to squirt water onto floor and soaking up with paper towels until there was no hint of yellow on the paper towels.
I squeezed the about 3 gallons of water containing a little Ar and gold into a bucket. It was quite yellow in color. I tried to precipitate the gold from this mostly water solution using SMB but only a few grams came down. It was still quite yellow. I boiled it down to about a quart and about 20 grams of gold self precipitated. I filtered the gold out of this solution which has turned a yellowish brown color. The remaining solution was sitting in the pyrex pan for almost 4 days when I noticed the crystals had formed. I was waiting to add the AR from dissolving the gold in the paper towell ashes to boiled down solution.
I still have to cut up and burn the deep purple stained pressboard floor and refine the ashes. I just thought you might like to see the crystals!
Best Regards,
Wayne
I had 8 filters full to the brim of clean gold from deplated items and some gold already recovered from inquarted jewelry items, approx. 20 grams to a filter dissolving in some AR outside in a coffee pot. After it quit fuming I put it and the plastic bowl it was in inside my storeroom to let it finish working while I did other chores.
My wife of 18 yrs whom I still love very much was putting a couple bags of aluminum cans into the same storeroom but didn't like the smell so she threw the bags of cans onto her pile from the open door! One of them fell into my bowl and coffee pot spilling the contents onto the pressboard floor!
She put on my gloves and started cleaning up the spill with paper towells. she is very mildly asthmatic anyway, so we ended up going to the E.R., 4 days later we were able to come home. Watching her suffer was the most traumatic ordeal I've ever been through!
I cleaned up what I could with paper towels using a spray bottle to squirt water onto floor and soaking up with paper towels until there was no hint of yellow on the paper towels.
I squeezed the about 3 gallons of water containing a little Ar and gold into a bucket. It was quite yellow in color. I tried to precipitate the gold from this mostly water solution using SMB but only a few grams came down. It was still quite yellow. I boiled it down to about a quart and about 20 grams of gold self precipitated. I filtered the gold out of this solution which has turned a yellowish brown color. The remaining solution was sitting in the pyrex pan for almost 4 days when I noticed the crystals had formed. I was waiting to add the AR from dissolving the gold in the paper towell ashes to boiled down solution.
I still have to cut up and burn the deep purple stained pressboard floor and refine the ashes. I just thought you might like to see the crystals!
Best Regards,
Wayne
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Nice crystals! And sorry to hear about your wife!
I’ve always thought that “Keep out of reach of children” should be “Keep out of reach of children and spouse”.
Luckily my workshop is a dedicated workshop, so there is no other traffic in there. If something potentially nasty is going on, the door is locked.
My son made his first attempt of “making it go booom” at the age of three. He’s a “creative lad with lots of initiative”
Wonder what those crystals are?
I would separate them from the liquid, dissolve in a minimum of water and test for gold. If it is gold chloride, the resulting gold after a sulphite reduction would be very high quality (recrystallisation is a great way to clean things). If it is not gold, then it’s just nice to get rid of it.
Regards
Peter
I’ve always thought that “Keep out of reach of children” should be “Keep out of reach of children and spouse”.
Luckily my workshop is a dedicated workshop, so there is no other traffic in there. If something potentially nasty is going on, the door is locked.
My son made his first attempt of “making it go booom” at the age of three. He’s a “creative lad with lots of initiative”
Wonder what those crystals are?
I would separate them from the liquid, dissolve in a minimum of water and test for gold. If it is gold chloride, the resulting gold after a sulphite reduction would be very high quality (recrystallisation is a great way to clean things). If it is not gold, then it’s just nice to get rid of it.
Regards
Peter
Too bad gold chloride crystals are a deep red. Anhydrous AuCl3 will never just crystallize out of solution Peter. Far too good of a Lewis acid, and far too happy to gain a proton 8)
Anhydrous AuCl3 is made from gold and chlorine, quartz tube and tube furnace. It is transiently stable in aqueous solutions, more so in alcohol and polar solvents if I remember correctly.
Anhydrous AuCl3 is made from gold and chlorine, quartz tube and tube furnace. It is transiently stable in aqueous solutions, more so in alcohol and polar solvents if I remember correctly.
