# What is a "tri-salt polymer" as described by this product that eliminates and prevents mold?

This answer mentions an anti-mold product called Concrobium Mold Control. The FAQ linked on their website says:

Q: I see Sodium Carbonate listed on the label. Is Concrobium Mold Control just Sodium Carbonate (washing soda) and water?

A: No. Sodium Carbonate is the listed “active ingredient” on the Concrobium Mold Control label, but in fact there are two other ingredients in the solution which, when combined with the sodium carbonate and the water, result in this patented tri-salt polymer that eliminates and prevents mold. (Sodium Carbonate and water alone are not effective against mold.) The solution contains no bleach, ammonia or VOCs. Our Material Safety Data Sheet is posted on our website.

The MSDS lists two particular ingredients:

Chemical Name            CAS #          % by Wt

Trisodium phosphate   7601-54-9           1-5
Sodium Carbonate       497-19-8           < 1


I'm guessing the third might be water.

Question: What might the term "tri-salt polymer" refer to in general, and if possible to answer, what might it be in this particular case?

I did find a patent in a google search but I'm not sure of it's relevance and I don't understand it.

## 1 Answer

Beside the three-step deprotonation of (ortho) phosphoric acid, $$\ce{H3PO4}$$, along

$$\ce{H3PO4 <=> H2PO4^- + H+ <=> HPO4^{2-} + 2H+ <=> PO4^{3-} + 3H+}$$

where each of the oxygen-bound hydrogen atoms may be substituted by a cation, phosphoric acid may dehydrate partially to yield polyphosphates. Which seems, reading a related Canadian patent CA2504014 (A1) (deposit in English), the working principle here:

(loc. cit., p. 6; cations generalized)

The know-how includes tuning the proccessing as such that the composition of these blend polyphosphates is obtained reliably, since the complete dehydration simply would yield the waxy polyphosphoric acid used as acidic catalyst in the lab.

• Names of elements aren't capitalised. Oct 8 '18 at 22:53
• Thank you for your answer. The Wikipedia subsection Polyphosphoric acids says ""backbone" chain of these types of molecules consists of alternating P and O atoms covalently bonded together. Polyphosphoric acid molecules can have dozens of such phosphoric units bonded in a row." Wow!
– uhoh
Oct 9 '18 at 0:44
• @Mithoron Agreed. Better to adhere to the rules of IUPAC's Red Book. Oct 9 '18 at 21:36
• @uhoh This pattern of smaller ions joining each other may occur with anions of other oxoacids, too. Beside the smaller dichromate anion, the silicates for example represent a multitude of different ways the formal $\ce{[SiO4]^{4-}}$ tetrahedra may be attached to each other (vertex, edge, face), too. Oct 9 '18 at 21:41
• This is really interesting, thank you! I'm going to retreat to a good book or three to read further; I'd never associated silicates and phosphates (I'm not a chemist) but will now. It's never too late to learn Chemistry.
– uhoh
Oct 10 '18 at 0:28