Spectrophotometric Determination of Hg II

Dithizone forms an orange complex with Hg(ll) ions and the complex is soluble in chloroform. 

Follow the same steps as in 17.7.1 but filter the precipitate in a prepared sintered glass crucible. After washing the precipitate with water, dry to constant weight at lOO C. Calculate from duplicates, the concentration of Hg(Il) in mol dm.  

Hg(ll) is a soft acid and tends to coordinate to soft bases e.g. Y and SCN . 

These are readily obtained by precipitating [Hgl4] by either of the two coinage metals. In the case of Cu, Cu(II) sulphate is reduced to Cu(I) prior to the precipitation. These 

Carry out the following sequence of reactions on a small quantity (0.02-0.025 g) of the prepared solid. Record and interpret your observations. 

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