[abcc]

A sample of pyrite is known to have approximately 90-95 wt. % Fe2S. It is analyzed by oxidizing the sulfur to SO4(2-), which is precipitated as BaSO4. How many grams of sample must be taken for analysis if a minimum of 1 g of BaSO4 is desired? ( a.m: Ba=137.33, Cl=35.45, Fe=58.847, O=15.99, S=32.06)

also , I would like to know what is pK(sp)??what is it physical significance??

[AWK]

Pyrite is FeS₂
According to shortcoming stoichiometry
FeS₂ ==> 2S ==> 2SO₄^2- ==> 2BaSO₄
try solve your problem