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JEE Mains 2015 Preparation › Physical Chemistry questions › %

0.85g sample of pyrites FeS2 was fused and sulphur oxidised to SO₄^2-.The ppt. of BaSO4 weighed 1.43g.Whats % of pyrites in the ore?
Ans43.22%

#Chemistry #Physical Chemistry

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6 Answers

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eureka123 ·2009-01-05 11:05:39

HELPPPPPPPPPPPP

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1357

Manish Shankar ·2009-01-12 03:56:50

mole of BaSO4 n=1.43/233

mole of FeS2=(1/2)n

%=(1/2)n100/0.85

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kunalb Bhattacharya ·2009-01-23 23:49:21

FeS₂ + O^2--->Fe + SO₄^2----> + 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)....

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24

eureka123 ·2009-01-23 23:51:08

thanx..

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kunalb Bhattacharya ·2009-01-23 23:55:37

cud u plz tell me the source f dis ques???i mean frm ne bk or magzine or tst paper????

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eureka123 ·2009-01-23 23:57:32

yaar.....my brother gave JEE 5 years back..............these questions are from his unsolved notes............

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