I'm sorry I was unclear about the sulfuric acid. Kirk is right of course. The reason I have a gallon of 37% Sulfuric Acid is that for a molar equivalent of 1 L of 50% NaOH, you will need about 1 L of 37% Sulfuric Acid, which is the strongest that can be bought on the open market here. You do not dump the acid onto the hydroxide solution. You must have it in a dilute form. I dilute it to about 3.7% so I have plenty of water ready to flush things with. I also like to have a little extra acid to be diluted kept around the lab to get the splashes, if any.
Sodium Hydroxide is far more harmful and quick acting to cause injury than Sulfuric Acid. That is not to say that they are not each dangerous, but the harm from Hydroxide is virtually instantaneous, especially to the eyes, whereas, you have a few seconds to rinse off the acid.
Also, this combination will generate heat but few fumes are given off. This often depends on the floor material.
This combination is also selected to help preserve my floor just in case.
Take care. All is well in my lab this AM. I left the still warm 1 L bottle in its containment bath of cold water overnight just in case. The lid was just a bit loose. So, if the bottle broke the hydroxide would be contained in a diluting water bath and that was in my stainless steel sink. The loose cap would prevent any potential explosive condition in case contaminants had gotten into the hydroxide somehow. It would also protect against a vacuum being created over the hydroxide as air and water vapor condensed as it cooled further.
Rodinal is perfectly safe albeit the solutions are very very alkaline and they must be handled as such. It is the mixers that have to take extra precautions.
We do not need a 50% solution of either NaOH or KOH. The KOH I got from The Chemistry Store was in the flake form. Less than 100 grams per liter are needed for Rodinal. If the flakes are poured into 750 ml of water at room temperature while stirring, there is no sticking to the bottom and the heat generated does not cause boiling. Add the sulfite next. The p-aminophenol base should dissolve, and you have produced a Rodinal expedient.
Can anyone tell me the solubility of potassium 4-methyl paraminophenolate in water, or where to find it?
No idea Patrick but I do have some formulae for High Concentration Metol devs, and I'm doing some sorting at the moment.
I'd say most all developers regardless of whether they start with sulfite, bisulfite, or metabisulfite have free SO3--. That's sulfite in solution, after all. Nothig special there.
Originally Posted by Ian Grant
Did you mean free SO2? (And not "free SO3--?) If so, once you've raised the pH so that the solution to where it is pretty much not acidic, then you don't have an free SO2 either. The SO2 that's dissolved will become SO3--. So there's no free SO2 in Rodinal.
So what did you mean?
Several of the existing formulas use 25 - 50% NaOH. That is the reason I mention what I did. Many require the use of solid NaOH which is just as bad.
It is but we have an excess, that's the nature of Metabisulphite it's seems more than the Molecular weight, and it acts that way in use.
I think the whole Bisulphite/Metabisuphite properties are poorly defined and explained, there is lot of free SO2 when you buy fresh Metabisulphite, not included in the MW.
All the work I can find is into how Metabisulphite is used in practice, and the small difference in the US grade "Bisulphite". I know from practical experience there's a difference.
With regard to the EZ-Rodinal, It would probable be best to dissolve the sulfite and hydroxide at about the same time. IIRC, the sulfite is endothermic. Certainly, the KOH is potentially dangerous. Worse yet is adding water to the dry hydroxide, either K or Na.
I have made KOH upon occasion. I had the potassium carbonate, and can get calcium hydroxide at a garden shop (they call it "slaked lime" or "hydrated lime") . Mix one molecular weight of each in water and you get a precipitate of calcium carbonate and 2 molecular weights of KOH dissolved in the amount of water you used. You'll be hard pressed to recover all the solution by filtering, but the amount that can be decanted after the limestone has settled will be the same strength as what is trapped in the limestone. Just get the precipitate out of the container before it dries if you want to get it out without some acid.
Go ahead. It's OK to laugh.
There's more than it "seems" as the metabisulfite uses some of the water it's dissolved in to make the SO3--.
Originally Posted by Ian Grant
But there's not going to be more than there actually is...
Almost forgot. The reason I asked about the metolate is that I tried the following:
K2SO3..................222 g, 45% w/w K2SO3 (100 g dry.)
Water to 500 ml.
If all dissolves, the solution will contain 28.8 grams K2SO4. It did not all dissolve. I wasted a lot of time trying to dissolve it by bringing the pH up to 14.5 (stupid meter didn't know any better). I added water to make 750 ml and it became clear in more ways than one. It still is a potent stock solution.
The K2SO4 is not much in the working solution, but is a fair proportion of the stock in terms of 4methyl paraminolphenol. In any case, something is not all dissolving that I thought ought to.
I won't laugh, but one operation I will not do is filter a concentrated KOH solution. Too much chance of an accident, and the KOH usually ends up dissolving the filter paper. The CaCO3 is colloidal and can go through the filter paper.
Best use a sintered filter for this one, if it even works.