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aga
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No experiment is useless.
That's like saying a negative experience is useless.
What happens is that people Learn at least something.
Even if it is just how to get carbon off the inside of an RBF.
I distilled weeds with suphuric acid.
Now i know not to poke the glass for hours, just get some pirahñas in.
Where i'm at, any experiment, useless or otherwise gives me useful experience.
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blogfast25
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Quote: Originally posted by aga  | No experiment is useless.
That's like saying a negative experience is useless.
What happens is that people Learn at least something.
Even if it is just how to get carbon off the inside of an RBF.
I distilled weeds with suphuric acid.
Now i know not to poke the glass for hours, just get some pirahñas in.
Where i'm at, any experiment, useless or otherwise gives me useful experience. |
Sorry, but I have to stand firm here.
A negative experience would be useless if it was predicted you'd have one. NO ONE sets out to have deliberate negative experiences, other than
sociopaths.
Now, running an experiment (without knowing the outcome but with a reasonable expectation of sucess) and getting a negative result, is something you
learn from, so that IS useful.
Trying to extract gold from urine is a negative experience that was entirely predictable: nothing was learned from the outcome. But time and resources
were consumed for no good reason: that's a lose-lose situation.
Even trying to extract gold from urine because it might get some carbon off your RBF isn't smart because it would be more interesting and productive
to formulate some theory based hypotheses re. how to best go about doing that and then testing these with well designed experiments.
Wasteful 'science' is pseudo-science. See the countless crackpots trying to build perpetual motion machines: it can't be done so don't try it.
[Edited on 8-6-2014 by blogfast25]
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aga
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At my stage of learning chemistry, even a certainty of a negative outcome is useful.
It shows the Theories to be correct, in that the reaction would Not occur, and experimental evidence would show me that to be true,
So a pre-determined Failure woud actually yeild a Positive learning experience (to me at least).
Waste. Ah. I could wax lyrical regarding Waste.
| Quote: | | crackpots trying to build perpetual motion machines |
Best way to deal with that is to Tax the Motion !
[Edited on 8-6-2014 by aga]
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blogfast25
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While my product is drying, here’s some more ‘random theorising’  on AJ’s
scheme:
"2 AlCl2(OH) (aq) + MgSO4 (aq) ---?---) Mg(OH)2 (s) + Al2(SO4)Cl4"
1. The Ksp of Mg(OH)2 is 5.6 x 10<sup>-12</sup>, that means that from a 1 M Mg<sup>2+</sup> solution Mg(OH)2 only starts
precipitating from about pH > 8.4. But at that pH, Al<sup>3+</sup> cannot stay in solution either.
2. Existence/availability of AlCl2(OH): although there is a CAS number for this formula, precious few sources stock it. Even arguably the largest
inventory in the world, Sigma Aldrich, does not stock it. I suspect it only really exists in solution, not as a pure substance. Some datasheets I
found indicate an BP of 100 C: that clearly refers to a solution, not an ionic solid.
3. Assume I’m wrong on all this and that Mg(OH)2 precipitates (but not Al). A solution that contains Al3+, sulphate and chloride in the molar ratios
of 2/1/4 would then be left behind. But it’s by no means certain that something like “Al2(SO4)Cl4” would crystallise out: whatever crystallises
out would have the lowest solubility limit of all possible ones.
[Edited on 9-6-2014 by blogfast25]
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blogfast25
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A bit more analysis of the presumed AlClSO4.6H2O compound.
1. Drying:
The product was dried in a CaCl2 desiccator and its weight recorded. After 4 days a constant weight of 6.86 g was noted, which remained stable for the
next 3 days. It’s reasonable to assume this to be a stable, dry hydrate of the product.
No HCl gas was ever observed during drying: if this compound does contain significant anounts of Cl, drying doesn’t destroy its structure.
2. Aluminium content:
Al content was determined by back titration of an excess Na2EDTA added to a precisely known sample of the dissolved compound. The excess Na2EDTA was
titrated with standardised ZnSO4.
Na2EDTA was standardised against reagent grade CaCO3, ZnSO4 against the standardised Na2EDTA solution. All solutions were nominally 0.05 M, all
titrations buffered with pH = 10 NH3/NH4Cl buffer and using Eriochrome T as indicator solution.
I obtained an Al w% = 9.4 w% for the sample.
Pure AlClSO4.6H2O would have an Al content of 10.13 %, pure AlCl3.6H2O 11.2 % and commercial aluminium sulphate hydrate about 9 %.
So the 9.4 % number isn’t really discerning enough, considering also there is some unknown uncertainty (measuring error) on that number.
Tomorrow I’ll carry out a semi-quantitative analysis of sulphate and chloride in the sample.
[Edited on 14-6-2014 by blogfast25]
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blogfast25
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1. Semi-quantitative determination of sulphate:
The previous titrations showed the sample solution to be about 0.05 M in Al, so if the empirical formula of the material is AlClSO4 then this solution
must also be 0.05 M in sulphate and 0.05 M in chloride.
50 ml of 0.05 M sample solution was placed in a beaker. 50 ml of 0.05 M MgSO4 was prepared and placed in a second beaker. Then 100 ml of 0.1 M
Ba(NO3)2 solution was prepared.
50 ml of the barium nitrate solution was added to both the beakers. Left: the sample solution, right: the MgSO4 solution:
The precipitate is the highly insoluble BaSO4, which forms in both solutions in roughly equal amounts (visual assessment).
This is unequivocal proof the material contains sulphate ions in its lattice.
2. Semi-quantitative determination of chloride:
The BaSO4 suspension of the sample solution was filtered on Buchner to remove all BaSO4 and the filtrate placed in a beaker.
About 100 ml of 0.05 M NH4Cl was prepared in another beaker.
To both was added about 50 ml of silver nitrate (AgNO3) 0.1 M. In both cases a comparable amount of insoluble AgCl precipitated. Left: sample solution
after filtering and addition of AgNO3 solution, right: NH4Cl 0.05 M after addition of the same amount of AgNO3 solution:
This is unequivocal proof the material contains chloride ions in its lattice.
3. Yield determination:
Based on the amount of product (6.85 g) obtained, assuming it is AlClSO4.6H2O and the 20 g of ASH I started from, the Actual Yield would be about 40
%. I think this could be improved by reducing the amount of HCl 37 % used.
4. Recrysallisation experiment:
The remaining 3.49 g of product were subjected to a recrystallisation test. The material was mixed with 5.4 g of water. This ratio amounts to a mol
fraction of AlClSO4 of about 0.033 which is comparable to that of hot, saturated ASH solutions.
The mixture was heated and the product dissolved quickly and to a clear solution. It’s now cooling to check if it will crystallise out.
5. Could this be a double salt of aluminium sulphate and aluminium chloride?
A double salt with the composition Al2(SO4)3.AlCl3.18H2O would correspond to the formula AlClSO4.6H2O, so it’s a possibility.
6. Another batch:
Another batch has now been prepared, this one from 40 g commercial ASH and 80 ml HCl 37 %, for further experimentation.
[Edited on 15-6-2014 by blogfast25]
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CHRIS25
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ASH? aluminium sulphate?
Do not understand this sentence at all: "....to a mol fraction of AlClSO4 of about 0.033 which is comparable to that of hot, saturated ASH
solutions......"
Well I always assumed it was a double salt because it fits the criteria: IE, separates back into its individual ions and is made up of (in this case)
1 metal and 2 acids.
Interesting what you are doing though I am now un-clear about your aims are with all this, what are you trying now to establish?
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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blogfast25
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ASH: aluminium sulphate hydrate.
0.033 mol fraction ( = mol substance / (mol substance + mol water)) is about the maximum concentration at 90 C for ASH. I used it here as a reference
point to try and create a saturated solution of the salt.
My goal here is to prove that the formula of this substance is AlClSO4.6H2O. Just because atomistry says so doesn't make it true,
especially in the light of the complete absence of any other references. There doesn't even seem to be a CAS or EINECS identifying number attributed
to this substance. That is HIGHLY unusual and made me sceptical regards it existence. But so far my data seem to confirm it...
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The Volatile Chemist
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You can make so many double salts, it seems unlikely they'd have a listing for every single one.
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blogfast25
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If a 'pure substance' is a stable compound there is absolutely no reason NOT to attribute an identifier like CAS or EINECS to it, although I'm
uncertain about the protocol. A double salt is a pure substance in its own right.
Whether the compound is actually useful or whether there are many similar ones is neither here nor there.
Your argument would be like a biologist saying: 'pff, there are that many species of beetles, why catalogue them all?' (it's a career ending opinion,
BTW! )
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CHRIS25
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As you know I found a number of patents with compositions of this stuff. But here is something, I know it is liquid form, but maybe something here
might interest you? Posted it anyway.
http://www.cleartech.ca/msds/NAID%20I-3.pdf
http://brevets-patents.ic.gc.ca/opic-cipo/cpd/eng/patent/209...
This next one mentions the following: Interesting?
"....separation of the precipitated hydrated aluminum chlorosulphate crystals ... even as double sulphates, as described in applicants' French patent
application No........" but can not seem to find this in the patent or the links, or anywhere for that matter.
http://www.google.pt/patents/US4124680
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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blogfast25
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Chris:
Thanks for the links. The first two relate to basic aluminium chloride sulphate, these contain hydroxy ions and are fundamentally different from what
we have. Note that the term 'chlorosulphate' is very misleading as it implies a salt of chlorosulphuric acid:
http://en.wikipedia.org/wiki/Chlorosulfuric_acid
Our product is NOT a chlorosulphate in that sense. 'Chloride sulphate double salt' is probably the best term to represent it.
The patent does suggest a composition of AlClSO4 6 - 7 H2O. Unfortunately patents are notoriously bad sources of information, as their purpose is
often more to obfuscate than to enlighten.
The weekend coming I'll be determining chloride content quantitatively, assuming the chosen method works. That should then allow a full compositional
determination of the material.
[Edited on 17-6-2014 by blogfast25]
[Edited on 17-6-2014 by blogfast25]
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blogfast25
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My jury is finally out (at least more or less) on the composition of the Al chloride sulphate double salt.
The chloride content was determined using Mohr’s titration: titration of chloride with silver nitrate and potassium chromate as indicator.
Because this titration has to be performed at pH 6.5 to 9, a pH at which aluminium would precipitate as Al(OH)3, the aluminium had to be eliminated
prior to the titration, as follows.
3.33 g of dried product (from the second batch) was accurately weighed (1 mg) and dissolved in 100 ml of water. A perfectly clear solution was
obtained. About 2 ml of 33 w% ammonia solution was then very gradually added to a pH of about 8. The aluminium precipitates as Al(OH)3.
This was filtered off with a Buchner filter and the filter cake washed repeatedly with small amounts of water until the total filtrate was about 200
ml. This was quantitatively transferred into a 250.0 ml volumetric flask and diluted to the mark.
The silver nitrate solution was first standardised against recrystallised sodium chloride.
The titration yielded a w% chloride of 12.7 w%. Combined with the previously obtained value of Al w% = 9.4 w%, from these values can be deduced that
the molar Al/Cl ratio of the original material is 0.995, in other words 1 (one). And from the neutrality requirement (Al<sup>3+</sup> +
Cl<sup>-</sup> + SO<sub>4</sub><sup>2-</sup> = electrically neutral) can be deduced that the molar ratio Al/Cl/SO4
= 1/1/1.
From this the water content could also be estimated and the formula of the material to be AlClSO<sub>4</sub>.7H<sub>2</sub>O
but I’m fairly sure that because of the indirect determination of water, there is some error on that 7. If it was actually 6, the overall formula
would be Al<sub>2</sub>(SO<sub>4</sub><sub>3</sub>.AlCl<sub>3</sub>.18 H<sub>2</sub>O.
[Edited on 21-6-2014 by blogfast25]
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CHRIS25
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Quite an extensive test, new methods here that I am not familiar with but this last bit lost me:
"""there is some error on that 7. If it was actually 6, the overall formula would be Al2(SO4)3.AlCl3.18 H2O""".
How did you get from 6 to 18 by subtracting 1? (I really must be missing something here)
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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blogfast25
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Simples, dear Watson.
Al2(SO4)3.AlCl3 is essentially 3 x AlClSO4. Since I suspect AlClSO4.6H2O may be closer to the truth than AlClSO4.7H2O, I need to multiply the 6 also
by 3, giving me 18.
To be honest, there's some uncertainty on that hydration number but water content is surprisingly difficult to determine accurately.
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blogfast25
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I've been invited by a German university researcher to co-author an academic paper on the synthesis, analysis and characterisation of this compound.
His own research confirms the composition I claimed and also found the hydration (per mole of Al) to be 7, as I found.
If all goes ahead as planned I'll report on where this 'child of ScienceMadness' can be found.
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MrHomeScientist
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Congratulations! That's very cool. A win for amateur science!
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blogfast25
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Thanks, MrHS!
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Velzee
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Wow, that's amazing, blogfast! This thread was a really good read, too. I love complexes and double salts—there should be a whole thread on the
syntheses and theories of syntheses of them!
Check out the ScienceMadness Wiki: http://www.sciencemadness.org/smwiki/index.php/Main_Page
"All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident."
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"¡Vivá Cristo Rey!"
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blogfast25
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Thanks Velzee. It'll be a couple of months before it gets published, I think...
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The Volatile Chemist
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man, that's crazy! Cool work. And as I was reading through this thread I was wondering who dug it up again. Cool to hear! Looking forward to reading
the paper.
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