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Author: Subject: Phosphate free - Trisodium Phosphate (TSP) = Sodium sesquicarbonate (50/50 sodium carb & bicarb...)
RogueRose
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[*] posted on 22-5-2020 at 10:19
Phosphate free - Trisodium Phosphate (TSP) = Sodium sesquicarbonate (50/50 sodium carb & bicarb...)


So I was browsing a janatorial supply catalog and found a strange listing. The box looked just like the normal TSP box but underneath in letters about 15% of the TSP heading it said "phosphate free". The "substitute was even smaller in a color that didn't stand out.

So I checked the SDS and found it listed as: Sodium sesquicarbonate. Huh, what's that. I look and see it as this:

Na2CO3 * NaHCO3 and from what I can see, it doesn't seem to be any different than mixing the two together, which I suspect it just might be, and for $18.99 for a 3lb box, I just wish I was in on that raquet!

So I'm asking if anyone knows if there is anything special about this compound. Also, would I get the same thing if I just mixed the carb & bicarb together or is there some special reaction that occurs with this pricey product?
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[*] posted on 22-5-2020 at 11:00


SOOOOO much easier not on the phone....

Well, ZTS16, my remark was a hastily posted link to sodium metasilicate info page, a sunnyside product page and no explanation.

Ive never encountered anything other than sodium metasilicate when purchasing TSP over the last decade. Ive seen MEK, Xylene disappear off shelf's and replaced with new stuff, fluorinated solvents too heavy to count as VOC's. things come and go, but ive never seen anything other for that product... for phosphate free TSP

I imagine its not that hard to look through a pile of MSDS sheets on a website like sunnyside to confuse two products and get excited, good or bad.. I think we have all done that at least a couple times, no?

so right or wrong, one could double check the MSDS.

I wouldn't buy TSP that was just sodium sesquicarbonate. but that's me, a personal opinion; at that point sign me up for a citrus cleaner, metasilicate or lye even.

Does that clarify my point?

(he non-sarcastically remarked) ... ((today seems like the day misunderstandings)) ... (((already peved a few people today, unintentionally of course))) ... ((((I've 3 children, my house is not quiet for more than a few min at a time))))

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it is indeed sold for cleaning, but the remarks I saw were about its use in the UK as a replacement for the laundry booster borax, as it had been deemed toxic and banned, restricted or something. so it doesn't really apply here in California, explains why I haven't seen that on the shelves

still think the metasilicate works better and is more interesting, though, granted, this is not a thread about that, sorry

[Edited on 23-5-2020 by violet sin]

[Edited on 23-5-2020 by violet sin]




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[*] posted on 23-5-2020 at 06:37


violet sin: What in the world does sodium metasilicste have to do with sodium sesquicarbonate?

RogueRose: Yeah it’s just a 1:1 mixture of bicarbonate and carbonate. It’s a racket indeed. Similar to the 10% HCl that sells for a higher price than the same volume of 31%, because it’s “Low Odor!”




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[*] posted on 23-5-2020 at 08:55


I think there is a little more to this than just a mix. Sodium sequicarbonate really is an existing compound, it can be considered a double salt of sodium carbonate and sodium bicarbonate. It is not a particularly interesting compound and solutions of this behave just like solutions of a mix of Na2CO3 and NaHCO3, but technically, the solid compound differs from a simple mix of Na2CO3 and NaHCO3.

Another similar example is alum. It is a 1 : 1 hydrated double salt of K2SO4 and Al2(SO4)3 and solutions of this are like solutions of mixes of K2SO4 and Al2(SO4)3, but there is a real compound, called alum, which is the double salt.




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[*] posted on 23-5-2020 at 09:27


I've still got a load of Sodium Metasilicate - what is it actually good for, does anyone know? I've UTFSE, but I've not really been able to find much of any information about it.
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[*] posted on 24-5-2020 at 08:23


Quote: Originally posted by woelen  
I think there is a little more to this than just a mix. Sodium sequicarbonate really is an existing compound, it can be considered a double salt of sodium carbonate and sodium bicarbonate. It is not a particularly interesting compound and solutions of this behave just like solutions of a mix of Na2CO3 and NaHCO3, but technically, the solid compound differs from a simple mix of Na2CO3 and NaHCO3.

Another similar example is alum. It is a 1 : 1 hydrated double salt of K2SO4 and Al2(SO4)3 and solutions of this are like solutions of mixes of K2SO4 and Al2(SO4)3, but there is a real compound, called alum, which is the double salt.
Yes, it is a double salt. I would argue though that double salts do not necessarily qualify as chemical compounds in their own right. Sodium bicarbonate and sodium carbonate will co-crystallize to form sodium sesquicarbonate, but ultimately you still have the same mixture of sodium, carbonate, and bicarbonate ions. No chemical reaction is taking place. As you said, in solution it is identical. The only difference is in the crystal structure. This goes for all alums as well. They're more like solid solutions than unique chemical compounds.



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[*] posted on 24-5-2020 at 09:33


There is one important difference between solid solutions and double salts. Double salts have specific ratios for their constituting ions, while solid solutions can have any ratio for constituting ions.

E.g. in alum, the K(+) ions and Al(3+) ions always occur in a 1 : 1 molar ratio. In sodium sesquicarbonate, the ratio of carbonate ions and bicarbonate ions also is exactly 1 : 1. The crystal lattice dictates the ratio of the different ions.

In a solid solution, any ratio is possible. A nice example is a solid solution of KMnO4 in KClO4. One can have pale pink solutions of this, with the ClO4(-) and MnO4(-) ions in a ratio of e.g. 10000 : 1, but one can also have very dark purple solid solutions, with the ClO4(-) and MnO4(-) ions in a ratio close to 1 : 1.

Another example of a solid solution is a solution of chromium sulfate in aluminium sulfate. Aluminium ions and chromium ions can be exchanged in the crystal lattice, without chaning the crystal lattice itself.

A nice example of a solid solution, which at the same time is a double salt, is a solution of chrom alum in ordinary alum. In this compound, the molar ratio of Cr(3+) and Al(3+) can be anything, but the molar ratio of [Cr(3+) + Al(3+)] and K(+) is exactly 1 : 1.





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[*] posted on 24-5-2020 at 10:06


Fair enough. The language that I used in my last post wasn’t correct when it comes to solid solutions vs double salts.

However, I think the point still stands that these double salts do not have unique chemical properties that differentiate them from a simple mixture of their constituent salts. They merely have different physical characteristics due to the fact that the ions present are arranged in a different physical configuration.




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[*] posted on 24-5-2020 at 10:26


Yes, from a chemical point of view they are not very different from mixtures. So, all in all we agree ;)



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