why to add h2so4 in estimation of barium sulphate
Answers
Answer:
When dilute sulphuric acid is added to barium chloride solution, barium sulphate is formed as a precipitate and hydrogen chloride is formed in aqueous solution. Explanation: According to the law of conservation of mass, mass can neither be created nor be destroyed.
H2SO4 reacts with Ba forming BaSO4 which is insoluble, so it forms a thin layer on the metal's surface, preventing a further action of the acid.
Only to those metals which react with (dilute) H2SO4 forming an isoluble layer (sulphate, oxide, ecc). PbSO4 is also insoluble (but less insoluble than BaSO4). Note that, instead, concentrated H2SO4 does dissolve those sulphates because they react forming hydrogen sulphates, which are soluble:
BaSO4 + H2SO4 <--> Ba(HSO4)2
Aluminum also is insoluble in that acid because it forms a tick layer of Al2O3. Tin also should be insoluble. Other metals as Cu, Ag, Au, Pt, ecc., are too noble to react with a generic non-oxidant acid. Yes, someone could say that hot, conc. H2SO4 is oxidant too...
The story would be very long...
Answer:
Above answer is totally correct.......