NaClO sodium hypochlorite, what we call bleach is a basic substance, the NaOH sodium hydroxide in solution helps to keep the chlorine gas dissolved in this alkaline water, the bleach can be about 94% water.
HCl Hydrogen chloride is a gas, when dissolved in water it makes an acid we call hydrochloric acid or HCl acid, this acid is about 68% water
If we mix this acid with a base we make a salt and neutralize both the acid and alkaline solution around pH 7 if in correct proportions,
HCl + NaOH --> NaCl + H2O
Here we took a strong acid and a strong base both can be dangerous to your skin, and mixed them into a solution you can eat or wash your eyes out with.
(Caution unless you know what your doing do not try this}
trying to do chemistry without studying and understanding completely what your doing, not only can it make a mess but it could blind or poison you.
When we mix the NaClO with acid we generate chlorine gas this is what oxidizes our gold, we also try to do this with an excess of acid, the acid is reduced by the oxidized gold to form chlorides the gold and three chloride join to form a salt of gold chloride AuCl3.
What happens if we have limited acid over use Hypochlorite to make chlorine in solution to dissolve our gold, the acid is turned to salt and the solution can become basic or even alkaline which can hold excess chlorine gas in this salt solution easier, than an acid solution will.
Cold solutions hold most gases like chlorine in them easier than a hot solution.
Chlorine will stay in an alkaline solution longer than it will a neutral solution, and is driven off faster in an acidic solution.
We could go on with what happens when we dissolve gold but you can read more about that on the forum, here is one place to read a little bit more kind of related.
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=37&t=16434&start=20
I do not know you have gold in solution, as far as you know you do not either, you may believe you do because you seen it disappear when you put it into acid and added the sodium hypochlorite, but without testing you could no longer see it, so your gold just disappeared, here is where using your test solution will prove to you where your gold is, by allowing you to see a reaction of reduced gold in your stannous chloride test, the violet color verifies your gold is or is not in solution, it is you eyes to allow you to see the gold when you can no longer see it. Note the stannous chloride test must be able to reduce the gold for the test to work, if you have too much oxidizer in solution like chlorine the gold will not reduce so you have to remove the oxidizer before the test will work.
This is also true for precipitating your gold with sodium metabisulfite, the SMB will not be able to reduce the gold in solution back to a metal if you have too much oxidizer like chlorine in solution, which just keeps re-oxidizing the gold back into solution as ions.
What could have happened with your gold? Is it still there?
What may have happened is you used way too much bleach, put your gold into solution, but also raised the pH of the acid to salt water or a basic solution, which will hold chlorine, besides the water involved in both the acid used, and the bleach used, water is also formed in the reaction, so at that point you could have had a pretty dilute solution of salt NaCl gold salt AuCl3 and water, mixed with chlorine.
Then you added sodium metabisulfite and added more water to the mix, which will also form bisulfate salts as the SO2 gas leaves solution, the chlorine overwhelming your SMB keeping your gold in solution.
With just a little gold salt dissolved in solution the color is yellow, but with as much water as you have and all of the other salts in solution and as dilute as it is, you may have dispersed the gold in solution so much it diluted the yellow to where you cannot see it.
Heating this solution will concentrate it and all of the different salts involved, it can also help to drive off free chlorine gas (better if solution is acidic), the SMB has already reacted and may or may not reduce your gold when you concentrate the solution, it could just form a more concentrated bisulfate salt, along with the other salts in your solution.
I would concentrate the solution, to drive off chlorine, when it gets concentrated, you could see salts forming, or maybe even some gold powder, if you used way too much SMB, maybe even elemental sulfur powders could form, these salts if formed depending on conditions could be base metal chlorides, and or sulfates, NaCl, and even chlorate, if too much bleach, many of which would be water soluble.
I would not concentrate it too far, I would bring it down in volume to not less than half the volume that it was when you dissolved it.
Check pH and add acid if needed, after it is more concentrated, to keep it at least slightly acidic.
If you wish to check to see if chlorine gas is coming off the fumes when heated, put a few drops of ammonia in the lid of the ammonia bottle the ammonia will fume hold the cap in the fumes coming from your solution while evaporating, when the chlorine and ammonia fumes mix the light colored smokes, will mix, and gets whiter forming ammonium chloride gas the white visible fume coming from the cap of ammonia proves chlorine gas, do not get the ammonia into your solution.
Do your stannous chloride test, if positive you found your gold,you can now see where gold is, you also know the chlorine is low enough to be able to reduce the gold.
At this point if gold is in solution, adding more SMB could precipitate your gold, or it may not, depending on conditions, you may find your only alternative if gold is in solution and will not precipitate is to cement the gold out of the acidic solution with a large piece of clean metal copper.
Remember your testing solution is your eyes to see where gold is and where it is not.
Now I cannot say that what I described above is, what has, or will happen, just what I suspect.
