Precipitate Formation: Cobalt(III)Saccharinate Hexahydrate

1. Precipitate Formation: Cobalt(III)Saccharinate Hexahydrate Two solutions are combined to form a precipitate. Connie Giroux Chemistry Outreach

2. Purpose • The solubility and insolubility of cobalt salts is demonstrated

3. 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.

4. Concepts • Double-replacement reactions • Solubility • Precipitates

5. 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 is AB + CD AD + CB • CoCl2.6H2O(aq) + C7H4NNaO3S.2H2O Co(C7H4NO3S)2.6H2O (s) + 2H2O + Na+ + Cl- • This is also known as a metathetical reaction.

6. 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.

7. 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.

8. 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.

9. 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.