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ajkoer

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About ajkoer

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    Inorganic chemistry, mathematics,statistics, astronomy
  1. To quote from Wikipedia (http://en.m.wikipedia.org/wiki/Water_of_crystallisation#undefined ): "Classically, "water of crystallization" refers to water that is found in the crystalline framework of a metal complex or a salt, which is not directly bonded to the metal cation." So per Wikipedia, the water molecule in the formed crystal structure that are not directly bonded to metal cation (usually containing a +2 and +3 cations as well as a −2 anions) are usually termed "water of crystallization". Now, in the case of copper(II) sulfate, it is more actually represented as [Cu(H2O)4]SO
  2. Here is an idea based on the reaction of the hydroxyl radical with graphite. Per this source "The reaction of hydroxyl radicals with carbon at 298 K" by M.F.R. Mulcahy, B.C. Young, to quote from the abstract: "The reaction of free OH radicals with graphite was studied in a flow system by mass spectrometry, the OH being produced by the reaction H + NO2 → OH + NO. The OH radicals react rapidly at 298 K to produce approximately equal amounts of CO and CO2." Link: http://www.sciencedirect.com/science/article/pii/0008622375902687 The reactions, involving radical species, appear to proc
  3. The starting materials are a copper alloy, air, moisture and NH4NO3. An electrochemical reaction proceeds with the reduction of the NH4NO3 to NH4NO2 (which is very poisonous and unstable usually forming N2, but the dry salt can explode, especially in the presence of impurities) and then further reduce to NH3. Interestingly, you did actually detect the smell of ammonia. Copper is a known sensitizer for ammonium nitrate (that is, NH4NO3 is now transformed into a sensitive explosive, probably due to the creation of NH4NO2 and at higher temperatures, other unstable intermediaries, so be v
  4. John: I agree on your comment on the reaction cited and have edited my comments to be more clear that the author is, in my opinion, referring to an electrochemical reaction using non-standard notation for that field, which certainly can be confusing and viewed, to quote you, as "utter garbage". But, your comment on the important of concentration is similarly misplaced, to the best of my understanding, in an electrochemical setting. That is why an insignificant amount of HOCl, found normally in Bleach, is still significant. The other less obvious point is that a low concentration, b
  5. John: Note my quote from the author: "Even though there is relatively little HOCl in bleach" the reaction with HOCl apparently proceeds nevertheless because of its greater electrial potential. Now, so called 'free-chlorine' (defined as Hypochlorous acid and hypochlorite ion) is in all of our drinking water unless you water is made safe via ozone or chloramine. Interestingly, employing higher chlorination levels is one way of addressing issues with declining water purity, so my suggested reaction path may be observed even more frequently in Aluminum alloy tanks with exposure to copper.
  6. OK, lets assume there is not ever a high concentration of any compounds to form a gaseous eruption. Also, your proposal of the action of Zn and water to form H2 is not likely given the water temperature. However, I believe your idea is close. I was recently exploring (seemingly unrelated to this topic) a hypochlorite based Aluminum and Copper battery. Here is the chemistry per my research. To quote (see http://www.exo.net/~pauld/saltwater/ and http://sci-toys.com/scitoys/scitoys/echem/batteries/batteries.html ): "In the bleach battery, sodium hypochorite (NaOCl), the major constituent
  7. John: Thanks for raising questions. I think we can forget the point on whether any more gas (meaning O2) is generated via iron bacteria as I do not feel it alone is the answer, but would explain, on testing the gas mixture, any increased in the amount of oxygen. The important point is that Fe(HCO3)2, all by itself, on standing with exposure to air breaks down releasing CO2 and deposits Fe2O3.xH2O and consumes O2. Absence oxygen, Iron bacteria could attack ferrous salts (including Fe(HCO3)2) depositing more iron oxide and,in the case of this bicarbonate, releasing CO2, Now, the hypo
  8. Yes, I agree if the water is pure it shouldn't make gas. Or, one could state, if it makes gas, the water is impure. So, are there rare instances in varying locales where the water could be impure? I claim the reported incidents indicate a possible yes as well as potentially newly implemented solutions in some countries (like adding CuSO4 to the water supply). Now, on the solubility of the CO2 in the context of the specifics of the water tank, there are several parameters to examine. First, solubility is a function of temperature. Also the presence of other dissolved gases (like O2), and I
  9. I like the concept of why it was felt necessary to add a cupric salt to the water storage tank to kill (Copper is highly toxic to lower organisms) micro-organisms. If they are present, some micro-organisms are reputedly capable of breaking the otherwise stable nitrates into nitrites (see, for example, page 527 at http://books.google.com/books?id=8aw4ZWLABQkC&pg=PA527&lpg=PA527&dq=bacteria+convert+gaseous+nitrogen+into+ammonia+nitrates+and+nitrites&source=bl&ots=SQWZ3JcRrc&sig=Of3QJShC3vIQrrFR_1Ah4-URVSY&hl=en&sa=X&ei=T-PIUYf-IeTx0wHvxIHYAQ&ved=0CDQQ6AEwA
  10. Now, to quote Wikipedia again: "In anything other than very dilute, cold solutions, nitrous acid rapidly decomposes into nitrogen dioxide, nitric oxide, and water: 2 HNO2 → NO2 + NO + H2O " So, assuming some very dilute aqueous HNO2 (or NH4NO2) is formed, it is stable, until the water temperature rises, or the solution becomes acidic. So, correct me, but dilution itself, is not a negative as it contributes to Nitrous acid's stability, and more interestingly, per this source, HNO2 has limited solubility (see http://pubs.acs.org/doi/abs/10.1021/j100333a025 ). The severity of pressure er
  11. John: One of the pictures I posted clearly shows that the top of the tank has been blow off as if by a pressure eruption. This observation is not consisent of a failure by corrosion (there is no solution contact on the top of the tank). Also, the corrosion argument can be used to support a pressure reaction before a mechanical failure. Galvanic corrosion, like for example, with the Zn-Cu couple, does consume Zn forming some Zn(OH)2 which can eventually lead to a failure. But the other product is a whole lot of H2 gas: Zn + 2 H2O ---Cu & Heat--> Zn(OH)2 + H2 in fact,
  12. If one accepts the presence of nitrates in the drinking water, then in the presence of the following metals Fe and Pb in neutral solutions, and Zn, Cd, Cu, Mg and Al also appear active (see "American journal of science", Volume 112, page 188 at http://books.google.com/books?id=MvcQAAAAIAAJ&pg=PA188&lpg=PA188&dq=zinc+reduces+nitrates+to+nitrites&source=bl&ots=Dq9GZDHiTU&sig=sVyXwq5mDYxfUJzj51enKIVdpjg&hl=en&sa=X&ei=K1K4UcXCGOji4AOJ0oDYBA&ved=0CFIQ6AEwCDge#v=onepage&q=zinc%20reduces%20nitrates%20to%20nitrites&f=false in reducing nitrates to nitrit
  13. John: I actually came up with something that supports your zinc-copper couple hydrogen based model (opened minded in spite of my critics). The argument goes, assume there is only a small amount of copper salt around (this has been one of main points of concern), but a double replacement reaction with Zn will deposit the copper on the tank's lining over time. So, with sufficient time and some copper presence, it could accumulate. Then, upon sufficient warming of the water, the reaction: Zn + 2 H2O ---Copper & Heat--> Zn(OH)2 + H2 (g) and more rapid generation of hydrogen co
  14. To quote a source (see http://cgmp.blauplanet.com/adv/nomol.html ): "At room temperature and at atmospheric pressure Nitric oxide is a colorless gas with low solubility in water". See also Wikipedia solubility table results at (http://en.wikipedia.org/wiki/Solubility_table#N ), low solubility indeed, .0056 g/100g water at 20 C. Now as NO molar mass is 30 g which would occupy 22.4 liters, the dissolved amount of gas of .0056 g equates to 4.2 ml. Now, add O2 to the water and things change as, to quote Wikipedia (http://en.wikipedia.org/wiki/Nitric_oxide ): "In water, NO reacts wi
  15. In my opinion, Points 3 and 4 are did not necessarily contradict. Timing is important, as Chlorine, per a source cited above, to quote: " Chloramine does not dissipate easily compared to chlorine." My take, although Cl2 can kill nearly all kinds of bugs, it dissipiates and the water can be subsequently contaminated with organic matter and bacteria (forming NH3). Hence, the argument for Chloramine, although a much weaker disinfectant, having greater longevity. You may be aware of some arguments about chlorine cleansers, that they can create super bugs in your home, well, at least, that is the
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