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What is the maximum concentration of equimolar solutions of ferrous sulphate and sodium sulphide so that when mixed in equal volumes , there is no precipitation of iron sulphide ?(For iron sulphide , K_(sp)=6.3xx10^(-18) ) |
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Answer» Solution :(i)Concentrationin x M Ferrous sulphate solution : `{:(FeSO_4 to , Fe^(2+) +,SO_4^(2-)),(x,xM,xM):}` (ii) Concentration in x M sodium sulphide : `{:(Na_2S to , 2Na_((AQ))^(+)+,SO_(4(aq))^(2-)),(x,"2X M","x M"):}` FeS is form by same concentration of solution(i) and (ii) in it. `[Fe^(2+)]=x/2 , [S^(2-]=x/2` `{:(FeS_((s))hArr , Fe^(2+) +, S^(2-)),(,x/2M,x/2M):}` `therefore K_(sp) (FeS)=6.3xx10^(-18)=(x/2)(x/2)` `therefore x^2=4xx6.3xx10^(-18) = 25.2xx10^(-18)` so `x=sqrt(25.2xx10^(-18))=5.02xx10^(-9)` M so , concentration `x=[Na_2S]=[FeSO_4]` `=5.02xx10^(-9)` M |
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