thanx..
0.85g sample of pyrites FeS2 was fused and sulphur oxidised to SO42-.The ppt. of BaSO4 weighed 1.43g.Whats % of pyrites in the ore?
Ans43.22%
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FeS2 + O2--->Fe + SO42----> + Ba2+---->BaSO4
Now mol wt of BaSO4=137+32+64=233
233 gm BaSO4 has 32 gm S
so,1.43gm----------0.1964 gm S(by calculation)
Again in FeS2,64 gm S combines with 56 gm Fe
Hence 0.1964 gm S--------56 x 0.1964 / 64==0.17185 gm Fe...
Hence total wt of FeS2 in ore==0.17185+0.1964=0.36825 gm, which is almost 43.3% of the given ore.....(Ans)....
cud u plz tell me the source f dis ques???i mean frm ne bk or magzine or tst paper????
yaar.....my brother gave JEE 5 years back..............these questions are from his unsolved notes............