Chemical Concepts Demonstrated: Precipitation, complex-formation reactions and constants, competing equilibria, solubility product constants
Demonstration:
The following solutions are added to a beaker containing 0.1M AgNO3 solution.
| Solution | Chemical Equation | Solubility Product Constant (K) | Observations: |
| Na2CO3 | 2 Ag+(aq) + CO32-(aq) <=> Ag2CO3(s) | 1.2x1011 | Off-white precipitate forms |
| NaOH | Ag2CO3(s) + 2 OH-(aq) <=> AgOH(s) + CO32-(aq) | 2.0x104 | Precipitate turns coffee-colored |
| NaCl | AgOH(s) + Cl-(aq) <=> AgCl(s) + OH-(aq) | 1.1x102 | Precipitate turns white |
| conc NH3 | AgCl(s) + 2 NH3(aq) <=> Ag(NH3)2+(aq) + Cl-(aq) | 2x10-3 | Precipitate dissolves |
| NaBr | Ag(NH3)2+(aq) + Br-(aq) <=> AgBr(s) + 2 NH3(aq) | 1.8x105 | Off-white precipitate forms |
| Na2S2O3 | AgBr(s) + S2O32-(aq) <=> Ag(S2O3)23-(aq) + Br-(aq) | 15 | Precipitate redissolves |
| KI | Ag(S2O3)23-(aq) + I-(aq) <=> AgI(s) + 2 S2O32-(aq) | 4.2x102 | Pale yellow precipitate forms |
| NaCN | AgI(s) + 2 CN-(aq) <=> Ag(CN)2-(aq) | 1.1x105 | Precipitate redissolves |
| Na2S | 2 Ag(CN)2-(aq) + S2-(aq) <=> Ag2S(s) + 4 CN-(aq) | 9.4x106 | Brown-black precipitate forms |