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Precipitate Formation: Cobalt(III)Saccharinate Hexahydrate

Two solutions are combined to form a precipitate.

Connie Giroux

Chemistry Outreach

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Purpose The solubility and insolubility of cobalt

salts is demonstrated

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Demonstration Sodium saccharinate and cobalt chloride

hexahydrate are extremely soluble in distilled water, but when combined, they produce an insoluble product, cobalt(III)-saccharinate hexahydrate.

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Concepts Double-replacement reactions Solubility Precipitates

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Double-replacement Reactions

In the reaction below, the double-replacement reaction occurs when the cobalt ion replaces the sodium ion producing a solid, and the sodium ion replaces the cobalt ion in solution.

General form of a double replacement reaction isAB + CD AD + CB

CoCl2.6H2O(aq) + C7H4NNaO3S.2H2O

Co(C7H4NO3S)2.6H2O (s) + 2H2O + Na+ + Cl-

This is also known as a metathetical reaction.

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Solubility Solubility refers to the amount of a solid

that dissolves in a solvent. In this demonstration, the solvent used

was distilled water which completely dissolved the solutes which were sodium saccharinate and cobalt chloride solids, indicating that they were highly soluble. The sodium saccharinate solution was also heated to ensure that the Na+ and Cl- ions would remain in solution when combined.

When the two solutions were combined, the solid, cobalt(III)saccharinate hexahydrate, was produced which is highly insoluble in distilled water.

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Precipitates Precipitation refers to a substance that

leaves a solution rapidly in the form of a solid known as a precipitate

In this demonstration, cobalt(III)-saccharinate hexahydrate precipitated out of the solution forming a pink solid, while the Na+ and Cl- ions remained in solution.

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Conclusion Sodium saccharinate and cobalt chloride

hexahydrate were completely dissolved in distilled water to form two solutions.

When combined, these solutions produced an insoluble product, cobalt(III)saccharinate hexahydrate.

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Comments Researchers have been studying

saccharin and its effects on human metabolism for many years. The addition of cobalt to the saccharin complex is also being study to see what effects, if any, that it also has.