Boric acid , on heating , loses water in there different stages at different temperatures ultimately giving boron trioxide or boric an hydride.
`underset(" Boric acid ")(H_(3)BO_(3)) overset(370 K)rarr underset(" Metaboric acid ")(HBO_(2)) + H_(2)O`
`underset(" Metaboric acid ")(4HBO_(2)) underset(-H_(2)O)overset(410 K)rarrunderset(" Tetraboric acid ")(H_(2)B_(4)O_(7))overset("Red heat")rarr underset(" Boron trioxide ")(2B_(2)O_(3)) + H_(2)O` .
