In the prepartion of `HBr` or `HI, NaX (X=Br,I)` is treated with `H_(3)PO_(4)` and not by concentrated `H_(2)SO_(4)` since,

In the preparation of HBr or HI, NaX (X=Br, I) is treated with H_3PO_4 and not by conc. H_2SO_4 and since

HI is prepared from Nal , using H_(3)PO_(3) but not H_(2)SO_(4) . Explain.

What is the action of concentrated H_2SO_4 on HBr and HI

BaO_(2)+H_(2)SO_(4) rarr BaSO_(4)+H_(2)O_(2) In the above method of preparation of H_(2)O_(2) , now-a-days H_(3)PO_(4) (conc.) is used instead of conc. H_(3)SO_(4) because :

H_(3)PO_(3) is added to KMnO_(4) solution acidified with H_(2)SO_(4) .

H_(3)PO_(2)+CuSO_(4) to Cu darr+H_(3)PO_(4)+HNO_(3)