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

$\underset{\text{white solid}}{2\mathrm{Ag}{\phantom{A}}^{+}+\mathrm{CO}{\phantom{A}}_3{\phantom{A}}^{2-}⟶\mathrm{AgCO}{\phantom{A}}_3}$

$\underset{\text{brown solid}}{\mathrm{Ag}{\phantom{A}}_2\mathrm{CO}{\phantom{A}}_3+2\mathrm{OH}{\phantom{A}}^{-}⟶2\mathrm{AgOH}+\mathrm{CO}{\phantom{A}}_3{\phantom{A}}^{2-}}$

$\underset{\text{white solid}}{\mathrm{AgOH}+\mathrm{Cl}{\phantom{A}}^{-}⟶\mathrm{AgCl}+\mathrm{OH}{\phantom{A}}^{-}}$

$\underset{\text{colorless}}{\mathrm{AgCl}+2\mathrm{NH}{\phantom{A}}_3⟶\mathrm{Ag}(\mathrm{NH}{\phantom{A}}_3){\phantom{A}}_2{\phantom{A}}^{+}+\mathrm{Cl}{\phantom{A}}^{-}}$

$\underset{\text{yellow solid}}{\mathrm{Ag}(\mathrm{NH}{\phantom{A}}_3){\phantom{A}}_2{\phantom{A}}^{+}+\mathrm{Br}{\phantom{A}}^{-}⟶\mathrm{AgBr}+2\mathrm{NH}{\phantom{A}}_3}$

$\underset{\text{colorless}}{\mathrm{AgBr}+2\mathrm{S}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_3{\phantom{A}}^{2-}⟶\mathrm{Ag}(\mathrm{S}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_3){\phantom{A}}_2{\phantom{A}}^{3-}+\mathrm{Br}{\phantom{A}}^{-}}$

$\underset{\text{yellow}}{\mathrm{Ag}(\mathrm{S}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_3){\phantom{A}}_2{\phantom{A}}^{3-}+\mathrm{I}{\phantom{A}}^{-}⟶\mathrm{AgI}+2\mathrm{S}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_3{\phantom{A}}^{2-}}$