Silicic Acid in phosphoric acid solution

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SUMMARY

The discussion centers on the behavior of Meta Silicic Acid (H2SiO3) in an 85%wt phosphoric acid solution. Participants agree that the acidic environment is likely to prevent the formation of polysilicic acid and instead promote the dissociation of H2SiO3 into water and silica (SiO2). The consensus is that a gelatinous amorphous hydrated silica will form, characterized as a polymer of Si(OH) and SiO units, rather than the stoichiometric dissociation indicated in the initial reaction equation.

PREREQUISITES
  • Understanding of acid-base chemistry, particularly in relation to silicic acids.
  • Familiarity with the properties and reactions of phosphoric acid (H3PO4).
  • Knowledge of silicate chemistry and the formation of silica (SiO2).
  • Basic principles of polymer chemistry as they relate to silicate structures.
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  • Research the properties and reactions of silicic acids in acidic solutions.
  • Study the formation and characteristics of gelatinous silica and its applications.
  • Explore the effects of temperature on silicate solubility and precipitation.
  • Investigate the polymerization processes of silicates and their industrial relevance.
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Chemists, materials scientists, and chemical engineers involved in silicate chemistry, as well as those researching the applications of phosphoric acid in various industrial processes.

JohnP
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Consider the following reaction:
3Si3N4 + 27H2O + 4H3PO4 --> 4(NH4)3PO4 + 9H2SiO3 --> ^4NH3(g) + 4H3PO4 + 9H2SiO3 --> 4H3PO4 + ??

The phosphoric acid solution is 85%wt.

In your fella's opinion, what happens to the Meta Silicic Acid (H2SiO3)? Is the solution to acidic to form a polysilicic acid?
Will this occur: H2SiO3 --> H2O + SiO2 and form a gelatinous poly silica? Something else?
I do know that at relatively low concentrations of this silicate based product (~100PPM @ 155C) the product will come out of solution.
Appreciate your thoughts, thanks guys.
 
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I would expect a gelatinous amorphous hydrated silica. It would be a polymer composed of Si(OH) and SiO units, not the stoichiometric dissociation that your equation suggests
 

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