Chemistry Stack Exchange is a question and answer site for scientists, academics, teachers, and students in the field of chemistry. It only takes a minute to sign up.
Sign up to join this community
I found two papers from which two different formulae for the tetrasilicate (tetrasilicic acid) are found:
1.https://www.sciencedirect.com/science/article/pii/S0022309302015491.
2.https://www.ncbi.nlm.nih.gov/pubmed/26482329.
Of course, the usual formula for polymerization of oxacids suggest the first one is the right one, that is, the tetrasilicate anion being $\ce,{Si_4O_9^{2-}}$, however, how to understand the second formula? Is something missing?
Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.
"Tetrasilicate" is one of special guys. For example, sulfate is $\ce{SO_4^2-}$, while $\ce{SO_3^2-}$ is sulfite. But tetrasilicate is $\ce{Si_4O_n^{(2n-16)-}}$ - thus, it simply has four $\ce{Si}$ atoms (without connotation that they have special number of oxygens near 'em): check for
http://www.biomedsearch.com/nih/Novel-silicate-anion-Si8O2212-Hydrothermal/11487344.html, which is also tetrasilicate (here tetrasilicate is $\ce{Si_4O_11^6-}$).
https://www.researchgate.net/publication/50934696_Preparation_structural_and_luminescent_properties_of_Ba2Gd2Si4O13Eu3_for_white_LEDs (tetrasilicate is $\ce{Si_4O_13^10-}$), etc.
[edited] I've found for you even tetrasilicate with 15 oxygens: https://link.springer.com/article/10.1007/s00710-016-0447-1
Also check for amicite (zeolite): it has approximation $\ce{K2Na2Al4Si4O16·5(H2O)}$. It seems for me like 16 oxygens is maximum for tetrasilicates, but maybe someone would disagree - interesting to know that other tetrasilicates exist.
