Silver Precipitates

Hazards

Avoid contact with silver compounds as they will stain skin and clothing.

Chemicals and Solutions

  • 0.1 M Na₂CO₃ (1 mL)
  • 0.1 M AgNO₃ (10 mL)
  • 0.1 M NaOH (10 mL)
  • 0.1 M NaCl (30mL)
  • 5 M NH₃ (35 mL)
  • 0.1 M NaBr (10 mL)
  • 0.1 M Na₂S₂O₃ (50 mL)
  • 0.1 M KI (10 mL)

Materials

  • 600 mL beaker
  • 200 mL water
  • Magnetic stirrer and bar

Procedure

  1. Add 200 mL water and a stirring bar to the 600 mL beaker and begin stirring.
  2. Starting with 1 mL of sodium carbonate add the solutions consecutively to the water in the order listed in the materials section. Precipitates will form and disappear.

Discussion

Precipitate Color Ksp Moles/L
Ag₂CO₃ white 8.1 x 10-12 1.2 x 10-4 most soluble
AgOH brown 6.8 x 10-9 8.2 x 10-5
AgCl white 1.8 x 10-10 1.3 x 10-5
AgBr yellow 7.7 x 10-13 8.8 x 10-7
AgI yellow 8.3 x 10-16 1.2 x 10-8 least soluble

\( \ce{ $\underset{\text{white solid}}{\ce{ 2Ag+ + CO3^2- -> AgCO3 }}$ } \)

\( \ce{ $\underset{\text{brown solid}}{\ce{ Ag2CO3 + 2OH- -> 2AgOH + CO3^2- }}$ } \)

\( \ce{ $\underset{\text{white solid}}{\ce{ AgOH + Cl- -> AgCl + OH- }}$ } \)

\( \ce{ $\underset{\text{colorless}}{\ce{ AgCl + 2NH3 -> Ag(NH3)2+ + Cl- }}$ } \)

\( \ce{ $\underset{\text{yellow solid}}{\ce{ Ag(NH3)2+ + Br- -> AgBr + 2NH3 }}$ } \)

\( \ce{ $\underset{\text{colorless}}{\ce{ AgBr + 2S2O3^2- -> Ag(S2O3)2^3- + Br- }}$ } \)

\( \ce{ $\underset{\text{yellow}}{\ce{ Ag(S2O3)2^3- + I- -> AgI + 2S2O3^2- }}$ } \)