02-20-04 00:28
No 489915
Found this interesting info on our favourite acids:
HYPOPHOSPHOROUS ACID
Boil water with phosphuret of barium. Part of the water is decomposed; a portion of the phosphorus combines with the hydrogen of the water, forming phosphureted hydrogen which escapes, and other portions produce hypophosphorous and phosphoric acids, by combining with its oxygen. These acids unite with baryta, the phosphate of baryta, which is insoluble, being left while the hypophosphite of baryta may be removed in solution by water.
To the solution of the hypophosphite gradually add diluted sulphuric acid, till no further precipitate appears; filter, that the sulphate of baryta formed in this manner may be separated; the solution contains the hypophosphorous acid.
The solution of the acid may be concentrated till it becomes viscid and crystalline. When subjected to an increased heat, the acid and water react upon each other; part of the acid acquiring oxygen from the water and also from another portion of acid which is decomposed, and producing phosphoric acid; while the phosphorus of the decomposed acid, along with the hydrogen of the water, form phosphureted hydrogen. All its salts are soluble; and it is a powerful deoxidating agent.
PHOSPHOROUS ACID
Phosphorous Acid is formed when phosphorus is inflamed in a smaller quantity of air than is necessary for its complete combustion, and even when phosphorus is exposed to the air at natural temperatures. It is mixed, however, with phosphoric or metaphosphoric acid. The process best adapted for preparing it in a pure state, was pointed out by Sir H. Davy. A piece of dry phosphorus is put into a tube retort, and bichloride of mercury in powder placed over it. On exposing the retort to heat, the phosphorus, as it rises in vapor through the bichloride, takes one proportion of chlorine from it, and a limpid fluid condenses in the receiver, a compound of chlorine and phosphorus. On mixing it with water. they mutually decompose each other, the chlorine combining with the hydrogen of a portion of the water, and forming hydrochloric acid, while the phosphorus takes the oxygen, and is converted into phosphorous acid; by heating the liquid till it becomes of a thick consistence, all the hydrochloric acid and most of the water are driven oft and the phosphorous acid, still combined with a portion of water, becomes a solid crystalline mass on cooling.
It has a sour taste and a disagreeable fetid smell. It reddens the vegetable blues, and when exposed to heat it is decomposed, a portion of phosphureted hydrogen being disengaged, and phosphoric acid remaining. It is a powerful deoxidating agent, and precipitates gold, silver, mercury, arid platinum in the metallic form.
HYDRIODIC ACID
Hydriodic acid gas is formed by the action of one part of phosphorus with ten of iodine and four of water. The iodine and water are put first into a very small glass-retort or flask, the phosphorus added, and a gentle heat applied with a spirit lamp. In a very short time, a brisk reaction commences, a slight explosion generally taking place within the retort from the heat produced inflaming a portion of phosphorus, and also from the disengagement of a little phosphureted hydrogen. Dense vapors are at the same time disengaged, and the hydriodic acid gas may be collected by displacement after these have been expelled. Water absorbs it as rapidly as hydrochloric acid gas, end it cannot be kept long over mercury, as this metal begins to act upon it whenever they come into contact, the mercury combining with the iodine, and leaving hydrogen gas. Phosphureted hydrogen is disengaged in considerable quantity towards the end of the operation; when it begins to come, it is recognized by the acid gas with which it is mixed producing with the air a whiter colored vapor than previously; the process should then be stopped to prevent it from accumulating. Fifty or a hundred grains of iodine, with the proper quantity of phosphorus and water, will be found quite sufficient, using a retort capable of containing about five or six ounces of water. Constant attention must be paid to this operation while it is going on.
A number of complicated changes take place during the preparation of this gas, from the reaction of the different substances mixed together and part of the newly formed products. Small cubical crystals may frequently be seen in the neck of the flask or retort employed; they consist of hydriodic acid and Phosphureted hydrogen, and are rapidly decomposed by water with effervescence, this fluid combining with the hydriodic acid. The hydriodic acid gas is produced by the iodine combining with the hydrogen of a portion of water which is decomposed, the oxygen uniting with the phosphorus.
Other processes for the preparation of hydriodic acid gas have been recommended, but there is none by which the beginner can prepare a small quantity more easily than that which has been described. There are several circumstances with respect to the Phosphureted hydrogen, and the other products that are formed at different periods of the process, according to the temperature applied, and the proportion of water employed, which require further investigation.
M. F. D’Arcet has proposed to prepare hydriodic acid gas in a very pure form by heating a solution of hypophosphorous acid, till it begins to give off Phosphureted hydrogen by decomposing water, after which it is to be cooled, and mixed with an equal weight of iodine. On subjecting the mixture to a gentle heat, the water affords hydrogen to the iodine, producing hydriodic acid gas, while its oxygen is transferred to the hypophosphorous acid.
It wasn't Me!
(Hive Bee)
02-22-04 11:54
No 490421
Nice info...Very nice indeed.
A Terrible though could have a Terribly long carrier
10-02-04 01:54
(Rated as: UTFSE!)
(Hive Bee)
10-05-04 23:01
No 534641
SWIX likes this, might give this a shot:
React BaCl2 with Na2HPO4 to obtain Ba3(PO4)2 which should precipitate out.
Take this and boil in water, BaO precips out and is filtered out. To the filtered solution add dil. H2SO4 until no more precipitation, filter. Filtered solution contains hypo.
Questions: (any comments welcomed)
What will then be best way to concentrate acid?
Sulphate interferes with HI/RP reaction, will it also interfere with I/hypo reduction?
Someone tried to tell SWIX yesterday that concentrating hypo by boiling can lead to an explosion. Can anybee shed any light on this? Not at all true as far as SWIX is aware.
***FriedPiper***
Reality is just a crutch for people who can't handle drugs...
(Of Counsel)
10-06-04 09:59
No 534695
Overheating hypo can lead to the creation of phosphine gas which can combust rather explosively when mixed with oxygen. Heating hypophosphorous acid in an open beaker with a fan blowing off fumes will not create a serious risk of explosion. Overheating it in a flask or a flask with condenser certainly can.
mostly harmless
(Hive Bee)
10-06-04 14:44
No 534734
Right so there is actually basis to that. Thanx geez, will remember that.
The sulphate must interfere of course so SWIX might UTFSE to suss out best way to obtain the straight acid.
***FriedPiper***
Reality is just a crutch for people who can't handle drugs...
(Wizard Master)
10-06-04 23:55
No 534800
Heating hypophosphorous acid in a O2 environment will cause the hypophosphorous acid to oxidise to phosphoric acid.
Strongly heating hypophosphorous acid will cause the hypophosphorous acid to decompose and form phosphine.
Therefore, hypophosphorous acid SHOULD NEVER be exposed to O2.
(Hive Bee)
10-07-04 20:16
No 534906
Ok sweet did some research, know all about it now.
180 celcius = oxidation to phosphoric.
Also it would appear BaSO4 precips out, taking care of that sulphate ion.
Cheers.
***FriedPiper***
Reality is just a crutch for people who can't handle drugs...
(Hive Addict)
10-09-04 16:38
No 535104
Can't get a response through PM so... Could CaCl2 bee used as a substitute for BaCl2? I did use the search engine using BaCl2, CaCl2 and substitute as keywords and a different application relating to these chemicals surfaced. In that particular application it mentioned that BaSO4 isn't water soluble but that CaSO4 is! Further down in that thread it mentioned that the CaSO4 solubility is minimal. A little Ca may not hurt but the sulfate? Would this convert to H2S in the HI rxn?
So what's the answer? I think I need to cut to the chase and start sending my PMs directly to Osmium or Unobtainium. I think we all should.
Who am I to tell you who to believe in, when all the masks they seem so damn deceiving...
(Hive Bee)
10-09-04 17:11
No 535110
Was meaning to reply, just been busy...
Also not completely sure of the answer. But I think Ba ion is neccessary so that the sulphate will precip out, it does need to be removed at some point.
***FriedPiper***
Reality is just a crutch for people who can't handle drugs...
(Hive Bee)
10-09-04 18:12
No 535123
HI at.mass 127.9079, M.P -54 C, B.P. -36 C
Very soluble in water (57%) to give acid solution
- forms 2, 3, 4H2O Hydrates.
Prepared from H2 and I2 with catalyst, or I2 plus red phosphorus plus H2O.
Aqueous hydriodic acid solution prepared I2 plus H2O plus H2S.
Warning: hydrogen sulphide (H2S M.P. -85 C, B.P. -61 C) is a very poisonous gas
produced by decaying animal or plant matter. Prepared FeS plus dilute acid, or in situ by hydrolysis of thiols.
(Hive Bee)
10-10-04 00:44
No 535160
Na2HPO4 is disodium phosphate. what would you want with that?
Ba3(PO4)2? BaO from this? no.
btw, "phosphuret of barium" is barium phosphide. easy and fast to make from phosphate and carbon, um, if you have an arc furnace handy. maybe you have two. and barium hypophosphite Ba(H2PO2)2 has about the same solubility in cold water as the chloride.
so anyways, are you asking how to get hypophosphorous acid from sodium hypophosphite, or ?
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