The chemical reactions involved in the conversion from Ba to BaSO4 are as follows:

Ba + 2H2O -> Ba(OH)2Ba(OH)2 + 2HNO3 -> Ba(NO3)2 + 2H2OBa(NO3)2 + H2SO4 -> BaSO4 + 2HNO3

So the overall reaction would be:

Ba + H2SO4 -> BaSO4 + H2