If I dry AR
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Assuming that with "AR" you are referring to aqua regia or a chloride salt solution of metals.
If you dry or evaporate the water from a solution of metal chloride ions you will have the salts or crystals of those metals as chloride salts. During the process, water is vaporized off, acids concentrate and begin to azeotrope and then decompose into vapors of the acids involved, the acidic salts will dry but will still hold moisture and can still be acidic in nature...
The gold chloride will still be salt of gold and of the acid (chloride ion), as the solution of dissolved gold concentrates as the solution is evaporated, you can come to a point the solution cannot hold the chloride salt of those metal ions, to the point where crystals of those metals begin to precipitate from the solution.
Boiling a solution you can have losses of gold through carryover of gold salts with the vapors and splashing of liquids and gases the process.
Keeping the solution from boiling C.M.Hoke suggested using a steam bath that would provide enough heat to slowly evaporate the solution (over a large surface area) but keep the temperature low enough so as not to actually boil the solution which would be a problem for losing gold in the process...
Gold chloride salt can begin to decompose around 160 deg C.
The gold chloride can become volatile if heated at higher temperatures (>180 deg C.), or baked dry in the process causing loss of gold in the fumes due to chlorine gas evolution carrying gold in those fumes...
When evaporated to salts of metal chlorides (if done properly) even then you may have some salts that will still be water-soluble, some of the gold salts may dissolve In water or some may need HCl added to get the metal back into the solution if the salts are calcined or baked dry some gold may have become reduced to metal in the evaporation process and may not be easy to get it to dissolve without using an oxidizer (Hoke page 55 discusses using chlorates with gold salts baked-on the dish...).
If you dry or evaporate the water from a solution of metal chloride ions you will have the salts or crystals of those metals as chloride salts. During the process, water is vaporized off, acids concentrate and begin to azeotrope and then decompose into vapors of the acids involved, the acidic salts will dry but will still hold moisture and can still be acidic in nature...
The gold chloride will still be salt of gold and of the acid (chloride ion), as the solution of dissolved gold concentrates as the solution is evaporated, you can come to a point the solution cannot hold the chloride salt of those metal ions, to the point where crystals of those metals begin to precipitate from the solution.
Boiling a solution you can have losses of gold through carryover of gold salts with the vapors and splashing of liquids and gases the process.
Keeping the solution from boiling C.M.Hoke suggested using a steam bath that would provide enough heat to slowly evaporate the solution (over a large surface area) but keep the temperature low enough so as not to actually boil the solution which would be a problem for losing gold in the process...
Gold chloride salt can begin to decompose around 160 deg C.
The gold chloride can become volatile if heated at higher temperatures (>180 deg C.), or baked dry in the process causing loss of gold in the fumes due to chlorine gas evolution carrying gold in those fumes...
When evaporated to salts of metal chlorides (if done properly) even then you may have some salts that will still be water-soluble, some of the gold salts may dissolve In water or some may need HCl added to get the metal back into the solution if the salts are calcined or baked dry some gold may have become reduced to metal in the evaporation process and may not be easy to get it to dissolve without using an oxidizer (Hoke page 55 discusses using chlorates with gold salts baked-on the dish...).
kurtak
Well-known member
To make more simple what butcher said
It depends on the conditions under which you "dry" the AR
The conditions being temperature as well as whether there is oxygen or no oxygen (oxidizing atmosphere or reducing atmosphere)
depending on those conditions the AR (with gold dissolved in it) can be "dried" so that it is "reduced" to the actual metal of gold (called calcination) --- OR --- most if not all the gold can vaporize (go up in smoke) - OR some will be reduced to gold & some will go up in smoke
Calcination NEEDS to be done under VERY controlled conditions - or (much) of the gold is likely to go up in smoke)
simply put - if you try to dry AR out on a hot plate - some of the gold will likely reduce to actual gold but some of it will most certainly go up in some --- how much goes up in smoke will depend on the above conditions
Gold salts (as chlorides) are very volatile so the likely hood of your gold going up in smoke is more likely then not
Kurt
It depends on the conditions under which you "dry" the AR
The conditions being temperature as well as whether there is oxygen or no oxygen (oxidizing atmosphere or reducing atmosphere)
depending on those conditions the AR (with gold dissolved in it) can be "dried" so that it is "reduced" to the actual metal of gold (called calcination) --- OR --- most if not all the gold can vaporize (go up in smoke) - OR some will be reduced to gold & some will go up in smoke
Calcination NEEDS to be done under VERY controlled conditions - or (much) of the gold is likely to go up in smoke)
simply put - if you try to dry AR out on a hot plate - some of the gold will likely reduce to actual gold but some of it will most certainly go up in some --- how much goes up in smoke will depend on the above conditions
Gold salts (as chlorides) are very volatile so the likely hood of your gold going up in smoke is more likely then not
Kurt
You can evaporate some of the acid off as it’s base is water but as most advise to dilute your solutions before precipitation it’s not really much help, if you can evaporate your spent solutions it helps with disposal.
First time posting on here... didnt know how to start a new thread. I need some help!! I was doing aqua regia and by mistake slightly contaminated my solution with another metal (beginner...). I figured I would filter, precipitate the gold and then start aqua regia again. As I started to precipitate the gold, my one solution turned a pale blue, and the other one went dark brown. Totally different colors but the same solution (split into two beakers so I had room for any over flow). What would cause this? Did I totally bugger it up?
