MrHomeScientist
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Making Orthosilicic Acid
Some time ago I made a video on making pure SiO2 by dehydrating orthosilicic acid. To make the acid, I combined solutions of sodium bisulfate and
sodium silicate (water glass) to form a gelatinous product. You can watch the video here: http://www.youtube.com/watch?v=G6sxdejGOqw&list=UUZOxhZo...
I recently got a question about what the equation is for this reaction, and after a lot of searching I haven't been able to find a source that lists
it. Here's what I think it is - can anyone confirm or deny? I don't want to give out incorrect information!
2NaHSO<sub>4</sub> + Na<sub>2</sub>SiO<sub>3</sub> + H<sub>2</sub>O =
H<sub>4</sub>SiO<sub>4</sub> + 2Na<sub>2</sub>SO<sub>4</sub>
Thanks!
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Spart
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Thank you for posting this, it was very helpful. I'm sure this is the right equation. I was embarrassed when I realized that my mistake was that I
forgot to include water in the equation haha.
On a side note, when I performed this, rather than getting a solution with clumps of the acid forming within it, as it did in your demonstration, my
entire solution just turned into one gelatinous mass of acid with very little liquid solution settled at the bottom. I am not quite sure why this
happened. Would it be because maybe my measurements of the chemicals were incorrect? I dehydrated the mass and it yielded just as one would expect,
nearly all silicon dioxide. After mixing the product in water and filtering it, I found very little of the material dissolved. If you have any idea
why the solution would turn into a whole mass of acid rather than a solution with bits of acid in it, please share your thoughts.
Thanks
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MrHomeScientist
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Hah! Were you the one that messaged me? That's pretty funny you found this. Well unless anyone comes up with a different answer, I think that is the
correct equation above!
My first thought on your entire solution solidifying is maybe you used more saturated solutions than I did, meaning you wouldn't have much water left
after the reaction was finished. Or, if you just poured the solutions together rapidly rather than dropping it in slowly as I did, that might have
caused it. In any case it sounds like your synthesis was very successful, so congratulations on that! Glad you liked my videos!
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White Yeti
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I gave this method a try, but it didn't work. I was using non TSP cleaning agent which contained sodium silicate and I reacted it with spa pH-down
which contained sodium bisulphate.
Instead of forming a gelatinous precipitate, the solution bubbled furiously. I was so startled that I didn't try again since.
Any idea as to what impurity might have caused this?
"Ja, Kalzium, das ist alles!" -Otto Loewi
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MrHomeScientist
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Quote: Originally posted by White Yeti  | I gave this method a try, but it didn't work. I was using non TSP cleaning agent which contained sodium silicate and I reacted it with spa pH-down
which contained sodium bisulphate.
Instead of forming a gelatinous precipitate, the solution bubbled furiously. I was so startled that I didn't try again since.
Any idea as to what impurity might have caused this? |
If you can find an MSDS or full ingredients list, that would give you the answer. Since they only "contain" the required ingredients, I'm sure there's
lots of other garbage floating around in your chemicals. My first thought would be a carbonate in one of them, which would react with the bisulfate to
form CO2.
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Spart
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| Quote: Originally posted by MrHomeScientist |
My first thought on your entire solution solidifying is maybe you used more saturated solutions than I did, meaning you wouldn't have much water left
after the reaction was finished. Or, if you just poured the solutions together rapidly rather than dropping it in slowly as I did, that might have
caused it. In any case it sounds like your synthesis was very successful, so congratulations on that! Glad you liked my videos!
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I think that it was a combination of both. I did indeed combine the 2 solutions rather fast and also had slightly more saturated solutions. Thanks for
the input.
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zhiang0113
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Hi all, I'm new to this forum, nice to meet you guys 
I've tried adding hydrochloric acid and sulfamic acid to aqueous sodium metasilicate. However, no gel or visible precipitate was formed.  Any ideas why?
Thanks!
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