Is boric acid the same as borax?

Date:9/14/2020 2:04:48 AM

Is boric acid the same as borax?

White powder crystal or scaly luster crystal with triclinic surface. It has a greasy feel and no odor. Soluble in water, alcohol, glycerin, ethers and essential oils. No smell. The taste is slightly sour, bitter and sweet. Greasy feeling in contact with skin. No change in exposed air. It can volatilize with water vapor. When heated to 100-105 ℃, a molecule of water is lost and metaboric acid is formed. When heated to 104-160 ℃ for a long time, it changes into pyroboric acid. At higher temperatures, anhydrous substance is formed. The pH of 0.1 mol / L aqueous solution was 5.1. 1g is soluble in 18ML cold water, 4ml boiling water, 18ML cold ethanol, 6ml boiling ethanol and 4ml glycerol. The solubility energy in water increases with the addition of hydrochloric acid, citric acid and tartaric acid. The relative density was 1.4347. Melting point 184 ℃ (decomposition). The boiling point is 300 ℃. The median lethal dose (LD50) was 5.14g/kg in rats. It's irritating. The lowest lethal dose is 640mg / kg for adults, 8.6g/kg for skin and 29mg / kg for intravenous administration for infants; 200mg / kg for infants. The maximum allowable concentration in air is 10mg / m3.



Borax chemical name is sodium borate, also known as Moonstone. Borax has sodium tetraborate decahydrate, sodium tetraborate pentahydrate and anhydrous sodium tetraborate. Sodium tetraborate decahydrate is also called sodium pyroborate, CAS number is [1303-96-4], the molecular formula is Na2B4O7 · 10h2o, and the molecular weight is 381.37. It is a colorless translucent crystal or white crystalline powder, monoclinic crystal system. It is odorless, salty, soluble in water and glycerin, insoluble in ethanol and acid, aqueous solution is weak alkaline. Its density is 1.73g/cm3 and it is weathered in dry air. When the temperature is higher than 56 ℃, pentahydrate is precipitated from the solution; when it is lower than 56 ℃, decahydrate is precipitated; when heated to 350-400 ℃, it is anhydrous; when heated to 878 ℃, it melts into glassy substance. The molten borax can dissolve many metal oxides and form compound salts of metaboric acid with characteristic color. This property of borax is called "borax bead test".



1. Different physical properties
Borax is a colorless translucent crystal Du or a white crystalline powder. Odorless, salty.
Boric acid is white Dao powder crystal or triclinic scale luster crystal with greasy handle and no odor.

2. Different chemical properties
Borax is easily soluble in water and glycerin, slightly soluble in alcohol, and the aqueous solution is weakly acidic.
The solubility of boric acid in water increases with the increase of temperature and volatilizes with steam.

3. Different uses
Borax can be used as detergent, cosmetic, insecticide, buffer solution and other boron compounds.
Boric acid can be widely used in glass industry. It can improve the heat resistance and transparency of glass products, improve the mechanical strength and shorten the melting time.