Question

what happen when we add caustic soda and copper sulphate solution into milk.

Answer 1

Copper forms many different complex's having a variety of colors, from red to green, from blue to black, and probably more. The formation of cupric oxide would account for the appearance of an insoluble black precipitate. This could happen from the decomposition of some of the cupric oxide. It is possible that the original cupric oxide appeared more blue than green, due to the blue cupric oxide solution. As the reaction proceeded, more and more of the cupric oxide precipitated to give that black-green precipitate, you observed.



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