angelhair
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The death of NaOH
Is it just me or have you noticed what is happening to the NaOH from suppermarkets and hardware stores?
Only about a year ago quality white 99% NaOH was available everywhere, but now what I find is this grey, yellow or pink crap from China that doesn't
even list % any more.
And what about the brand name, "Mechanix" what the hell is that!! I feel really pissed off and completely insulted at what is happening at the retail
level.
The quality of just about everything has dropped and I am expected to except it as a fact and still pay the same price or more. Is this happening to
your NaOH?
[Edited on 3-11-2008 by angelhair]
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johnnybobonny
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The same's been happening around here. Thankfully, you can quite readily order it elsewhere, albeit at an inflated price.
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Picric-A
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Our local DIY store sell it at 98% purity5, which comes as pure white prills.
Boots also sells 98% pure stuff for around £1. 50 for 500g, not bad price...
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chloric1
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Lowes still sells the tall 2 pounds jar of 100% NaOH and I have used it for making soap numerous times without issue! Thankfully, with the popularity of biodeisel spreading, a few ebay sellers are
selling it at reasonable cost. Also, this is a good source for KOH for better solubility in water and alcohol. Never tried potassium soaps yet. I
think they might be jelly like.
[Edited on 11/4/2008 by chloric1]
Fellow molecular manipulator
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Phosphor-ing
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If I'm not mistaken K soaps are the liquid type. While Na soaps are the standard bar variety.
"The nine most terrifying words in the English language are: 'I'm from the government and I'm here to help.'" -Ronald Reagan
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UnintentionalChaos
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I've never made potassium soaps, but I have heard that a potassium soap will eventually harden up as well, although it takes longer. Liquid soaps are
made by flooding the reaction mix with water before the bars solidify (potassium works better for this) or something along those lines, assuming of
course that your idea of liquid soap is actually soap and not just a mix of thickeners and surfactacants. I've never made the potassium flavors, just
read about them in several books.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Formatik
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Long gone from most supermarkets. Harder to find in some hardware stores. Sometimes you just have to look harder. Like the 3-5% NH3 solutions even if
clear almost always have foam in them nowadays, but then I travel to a grocery store in another area, and find some that has no foam. Well, I'll be
damned.
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chief
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I was thinking about an electrolysis of Na2CO3 to get NaOH, like this:
==> anode close to the surface,
==> high current-density, so the CO2 would be so much that it would escape, having not enough time to dissolve
==> rising temperature near the surface (at the anode) would hinder CO2-dissolution additionally, because the solubility decreases with temperature
==> if the temperature-distribution could be made inhomogeneous, at the top higher than at the bottom (where the kathode would be), then mixing of
the whole thing would be sort-of hindered, and the NaOH-solution could concentrate on the ground.
Only the H2-generation could serve as a mixing-agitator, so the H2-stream would have to be homogeneously distributed over the whole-surface-diameter
of the electrolytic cell.
As electrode-material could, as I recall from a patent, stainless steel or iron or steel be used, as these passivate in the alcalic conditions. The
mentioned patent was about electolytic production of H2 and O2, the electrolyte was too NaOH or Na2CO3, not getting used up ...
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kclo4
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I think someone on this board at one time claimed Ca(OH)2 + Sodium Sulfate (or Carbonate) would precipitate the Calcium salt, leaving the Sodium
Hydroxide In solution.
I know these sorts of reactions are totally possible with some things, but I don't know if this is one that works.
Might be worth looking into if you can easily get calcium hydroxide.
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497
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That is a well known method for making NaOH, and it does work. The filtration of the precipitated insoluble calcium salt can be a pain in the ass
though.. Especially if you don't have a vacuum filtration setup.
Since I get 50 pounds of Ca(OH)2 for $25, this route looks quite attractive.. I haven't tried it yet, haven't needed a large amount of NaOH.
[Edited on 4-11-2008 by 497]
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chief
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I thought the Ca(OH)2-method works only with Na2CO3; but it seems possible because the Ca-sulfate is insoluble too. Main thing:tha CaSO4/CaCO3 hasto
be more insoluble than the Ca(OH)2, which is only slightly soluble (as the CaSO4!); maybe the CaCO3-route (really insoluble) is more efficient.
Anyhow: 50 pound of Ca(OH)2 are much cheaper, in the hardware-store: only (3.50 - 5.00) EUR !
The Ca(OH)2 is used for construction, just like cement (probably also in the future), and is in the same area of the store.
But one still has to get the Na2CO3 or Na2SO4 ! It would be easier, if NaCl could be used, but thatfor an insoluble Chloride would have to be ppt.
out; and the chloride would have to be more insoluble than the hydroxide; don't know if Silver could work: (g/(100 ml), 2 temperatures)
Silver chloride AgCl 0.0001923 0.000052
But I doubt the Na2SO4-route works:
Calcium sulfate CaSO[4].2H[2]O 0.223 0.244 0.255 0.264 0.265 0.244 0.234 0.205
Calcium hydroxide Ca(OH)[2] 0.189 0.182 0.173 0.16 0.141 0.121 0.086 0.076
As can be seen, the Ca-hydroxide is more insoluble than the sulfate ! I bet it doesn't work !
But I _know_ it's possible to use Na2CO3;
==> the CaCO3 is really (water)insoluble (see any chalc-mountains: millions of years of rain don't dissolve it; corals ...)
==> it was done like that, industially, 100 years ago
The CaCO3resulting may be heat-treated (900 celsius ?), to give CaO again, ...
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Formatik
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You would probably have to start off using a slurry of Ca(OH)2, if using Na2SO4. Adding it to boiling dilute aq Na2SO4 under stirring. That's how it
has been done for KOH starting with K2CO3. I would do also it in an iron vessel, since we know solid NaOH attacks glass, concentrated solutions more
slowly, with hot solutions worse, forming sodium silicate. Na2CO3 is more preferable due to solubility difference.
[Edited on 5-11-2008 by Formatik]
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chief
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| Quote: | Originally posted by Formatik
You would probably have to start off using a slurry of Ca(OH)2, if using Na2SO4. Adding it to boiling dilute aq Na2SO4 under stirring. That's how it
has been done for KOH starting with K2CO3.
[Edited on 5-11-2008 by Formatik] |
With an carbonate it may work (K2CO3,Na2CO3), but with Na2SO4 ???
==> CaSO4 is double as good soluble as Ca(OH)2, so why should any OH get out of the Ca(OH)2 ?
==> also industrially it isn't done via the Na2SO4-route (which doesn't work, probably), and Na2SO4 is a cheap end-material with few uses only.
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kclo4
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yeah I wasn't to sure.
Well, for most Na2CO3 is a lot easier to get then the sulfate anyways. All you need to do is boil common baking soda for a while, it decomposes
pretty easily.
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smuv
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You can get Na2CO3 from virtually any supermarket in the US as a product called washing soda. Its in the cleaning aisle usually right next to the
bleach and ammonia.
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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not_important
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| Quote: | Originally posted by kclo4
yeah I wasn't to sure.
Well, for most Na2CO3 is a lot easier to get then the sulfate anyways. All you need to do is boil common baking soda for a while, it decomposes
pretty easily. |
For this application just using Ca(OH)2 and NaHCO3 works, boil the solution to drive off CO2, CaCO3 ppts out. In effect
Ca(OH)2 + 2 NaHCO3 => 2 NaOH (aq) + CaCO3 (s) + CO2 (g) + H2O
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kclo4
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Actually you better turn it into Na2CO3 first!
Ca(OH)2 + 2NaHCO3 = CaCO3 +Na2CO3 + 2H2O
you'd need to add more Ca(OH)2, which seems pointless since you do the same steps anyways.
[Edited on 5-11-2008 by kclo4]
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