Can anyone tell me the properties of silicic acid Silicic acid or carbonic acid who is more acidic

The simple silicic acid is orthosilicic acid Si(OH)4, or written as H4SiO4, with an ionization equilibrium constant k1=. It is a weak acid, and its salts have hydrolysis in aqueous solution. Free silicic acids, including metasilicic acid (H2SiO3) and disililicic acid (H2Si2O5), are very weakly acidic.

The ionization equilibrium constant of metasilicic acid k1 = 2 * 10-10 (room temperature), orthosilicic acid is stable in the range of pH2-3, but if the supersaturated H4SiO4 solution is left for a long time, there will be amorphous silica precipitation, and appear as colloidal particles, precipitates or gels. Some of the water in the gel evaporates to give a porous, dry solid gel, the common silica gel. This silicate gel has strong adsorption and can be used as a moisture-absorbing desiccant, catalyst, or as a carrier for other catalysts.

Reference: baidu

The properties of silicic acid are divided into physical and chemical properties.

1. Physical Quezhou reto: Silicic acid is a glassy colorless and transparent amorphous particle, with a relative density of 2.1 to 2.3, which is insoluble in water and alcohol. Silicic acid has a variety of molecular compositions, such as disililicic acid, metasilicic acid, orthosilicic acid, etc.;

2. Chemical properties: insoluble in acid, soluble in caustic solution. Compared with silica gel, it contains more hydroxyl groups, and it is a kind of silica gel with high purity reagent.

Heated to 150 degrees Celsius to decompose into silica, silicic acid is chemically stable, does not react with any substance except strong alkali and hydrofluoric acid, and reacts violently with hydrofluoric acid and decomposes.

Carbonic acid is highly acidic, and the method of CO is passed into the Na SiO solution and there is a gelatinous precipitate to form, which proves that carbonic acid is more acidic than silicic acid. Acids are less soluble in water and are weakly acidic. Silicic acid acidity is weaker than carbonic acid, it can be proved by the reaction, because of the introduction of carbon dioxide into the silicate solution, it can be seen that the solution becomes turbid, because of the formation of insoluble silicic acid precipitation, the reaction principle is strong acid to weak acid, indicating that bismuth carbonate silicic acid is strong.

Pure carbonic acid is an unstable crystal in the presence of C(OH) and decomposes violently when exposed to water. Carbonic acid is very low, and its saturated aqueous solution pH is about, and the normal rainwater pH is because CO dissolves in rainwater to produce carbonic acid. Its aqueous solution is acidic, so it can discolor the indicator (it can make the litmus solution red).

Silicic acid is chemically stable, does not react with any substance except strong alkali and fluoric acid, and reacts violently with fluoric acid and decomposes.

Chemical properties of silicon.

Silicon is inactive at room temperature, and its main chemical properties are as follows:

1) Interaction with non-metals.

Si can only react with F2 at room temperature, and burns instantaneously in F2 to generate SiF4

si+f2 ==si+f4

When heated, it can react with other halogens to form silicon halide, and react with oxygen to form SiO2:

si+2f2 sif4 (x=cl,br,i)

Si+O2 SiO2 (microstructure of SiO2).

At high temperatures, silicon is combined with non-metallic elements such as carbon, nitrogen, and sulfur to form silicon carbide SiC, silicon nitride Si3N4 and silicon sulfide SiS2, respectively.

si+c sic

3si+2n2 si3n4

si+2s sis2

2) Interaction with acids.

Si is passivated in oxygenated acids but reacts with hydrofluoric acid and its mixed acids to produce SIF4 or H2SIF6:

si+4hf sif4↑+2h2↑

3si+4hno3+18hf ==3h2sif6+4no↑+8h2o

3) Interaction with alkali.

Amorphous silicon reacts violently with alkali to form soluble silicate and releases hydrogen

si+2naoh+h2o ==na2sio3+2h2↑

4) Interaction with metals.

Silicon can also be combined with calcium, magnesium, copper, iron, platinum, bismuth, etc., to form corresponding metal silicides.

Silicic acid is a white powdery solid, insoluble in water, its acidity is weaker than carbonic acid, silica is the anhydride of silicic acid, but silica is insoluble in water, so it can not be directly reacted with silica and water to obtain silicic acid, can only be prepared by soluble silicate and acid reaction. As. NaSiO3+2HCl=2NaCl+H2SiO3 precipitation.

Metasilicic acid is acidic, silicic acid, formerly known as metasilicic acid, is a dibasic weak acid, insoluble in hydrochloric acid, sulfuric acid, soluble in hydrofluoric acid. Soluble in potassium hydroxide or sodium hydroxide solution, potassium silicate K2SiO3 or sodium silicate Na2SiO3 and water will be generated.

Metasilicic acid. Metasilicic acid contains a trace amount of potato Youshan elements that are beneficial to human health, which is easily absorbed by the human body and can effectively maintain the body's electrolyte balance and physiological functions. Medium.

Metasilicic acid-containing water is widely distributed in China and is found in many provinces, municipalities and autonomous regions.

Metasilicic acid is used for the adsorption of gases and vapors, the decolorization of oils and waxes, and the preparation of catalytic mixtures and their carriers.