Search results
Results from the WOW.Com Content Network
The first crystalline silicic acid was prepared from the phyllosilicate natrosilite (Na 2 Si 2 O 5) in 1924. More than 15 crystalline acids are known and comprise at least six modifications of H 2 Si 2 O 5 .
Here, the silicic acid H 4 SiO 4, or Si(OH) 4, which is equivalent to SiO 2 · 2 H 2 O represents hydrous or amorphous silica for the sake of simplicity in aqueous chemistry. Indeed, the term silicic acid has traditionally been used as a synonym for silica, SiO 2. Strictly speaking, silica is the anhydride of orthosilicic acid, Si(OH) 4.
Orthosilicic acid (/ ˌ ɔːr θ ə s ɪ ˈ l ɪ s ɪ k /) is an inorganic compound with the formula Si(O H) 4. Although rarely observed, it is the key compound of silica and silicates and the precursor to other silicic acids [H 2x SiO x+2] n. Silicic acids play important roles in biomineralization and technology.
Example Bjerrum plot: Change in carbonate system of seawater from ocean acidification.. A Bjerrum plot (named after Niels Bjerrum), sometimes also known as a Sillén diagram (after Lars Gunnar Sillén), or a Hägg diagram (after Gunnar Hägg) [1] is a graph of the concentrations of the different species of a polyprotic acid in a solution, as a function of pH, [2] when the solution is at ...
If the pH is reduced below 7 or if salt is added, then the units tend to fuse together in chains. These products are often called silica gels. If the pH is kept slightly on the alkaline side of neutral, then the subunits stay separated, and they gradually grow. These products are often called precipitated silica or silica sols.
Sulfuric acid and sodium silicate solutions are added simultaneously with agitation to water. Precipitation is carried out under acidic or basic conditions. The choice of agitation, duration of precipitation, the addition rate of reactants, their temperature and concentration and pH can vary the properties of the resulting silica. The formation ...
Hydrated silica is a primary ingredient in modern toothpastes, serving as a high performance abrasive during cleaning. [1]Hydrated silica is a form of silicon dioxide, which has a variable amount of water in the formula.
Silicic acid (H 4 SiO 4) in the silica-enriched fluids forms lenticular, nodular, fibrous, or aggregated quartz, opal, or chalcedony that grows within the rock. [5] Silicification happens when rocks or organic materials are in contact with silica-rich surface water, buried under sediments and susceptible to groundwater flow, or buried under ...