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Give physical and chemical properties of Orthoboric acid |
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Answer» Solution :PHYSICAL properties : Orthoboric acid, `H_3BO_3` is a white crystalline solid, with soapy touch. It is sparingly soluble in water but highly solublein hot water. It is also formed by the hydrolysis (reaction with water or dilute acid) of most boron compounds (halides, hydrides, etc.). It has a layer structure in which planar `BO_3` units are joined by hydrogen bonds as shown in figure.  Chemical properties: It can be prepared by acidifying an aqueous solution of borax. `Na_2B_4O_7+ 2HCl + 5H_2O to 2NaCl + 2B(OH_3)` Boric acid is a weak monobasic acid. It is not a protonic acid but acts as a LEWIS acid by accepting electrons from a hydroxyl ION : On heating, orthoboric acid above 370K forms metaboric acid, `HBO_2`which on further heating yields boric oxide, `B_2O_3` . `H_3BO_3 OVERSETDELTATO HBO_2 oversetDeltatoB_2O_3` |
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