How to make boric acid

How to make boric acid

Boric acid has formula H3BO3, appearance – the crystals of a "scaly" look which do not have color and a smell. Is weak acid, stability keeps only up to the temperature not over 70 degrees. How it is possible to receive this substance?


1. At excess of a limit of temperature, there is such reaction: H3BO3 = HBO2 + H2O as a result turns out metaboric acid which is also very unstable. If to continue heating, metaboric acid will be transformed to tetraboric (H2B4O7) which will practically at once decay: H2B4O7 = 2B2O3 + H2O

2. In the industry the main way of receiving boric acid is influence by sulfuric acid on boron-containing concentrates. For example, on the so-called "datolitovy concentrate" representing itself raw materials of complex structure. Its main components – datolite (a formula – CaBSiO4 (OH)), quartz, calcite and also the difficult complex connections containing iron, aluminum, magnesium, calcium. In strongly simplified look, this reaction can be written thus: CaBSiO4 (IT) + H2SO4 = H3BO3 + SiO2 + CaSO4

3. A desirable product of reaction, boric acid, separate from mix of products by means of washing with a large amount of water, then filter it, cool, allocate and clean, bringing to the required purity degree.

4. In vitro boric acid can be received influence of strong acid (for example, salt) on a drill (i.e. disodium salt of tetraboric acid). Reaction should be carried out when heating in big excess of water. It goes as follows: HCl + 5H2O + Na2B4O7 = 4H3BO3 + 2NaCl After cooling of reactionary mix, the formed boric acid "drops out" in the form of scales. They should be separated and subjected to further cleaning.

Author: «MirrorInfo» Dream Team