Chromium(III) Hydroxide Precipitation
CrCl3 + 3NaOH → Cr(OH)3↓ + 3NaCl
Overview
Chromium(III) chloride reacts with sodium hydroxide to form a green gelatinous precipitate of chromium(III) hydroxide (Ksp = 6.3 × 10⁻³¹). Cr(OH)₃ is amphoteric, dissolving in both excess acid and excess NaOH. In excess NaOH, it forms the green chromite ion [Cr(OH)₄]⁻.
Participants
| Role | Substance | Coefficient | State |
|---|---|---|---|
| Reactant | Sodium Hydroxide NaOH | 3 | (aq) |
| Product | Sodium Chloride NaCl | 3 | (aq) |
Everyday Example
The green color of some gemstones like emerald is due to chromium(III) ions, the same oxidation state that produces this green precipitate.
Industrial Importance
Chromium(III) hydroxide precipitation is used in chromium removal from industrial wastewater, particularly from chrome plating and leather tanning effluents.
Properties
- Type
- Precipitation
- Reversible
- No
- Energy
- Exothermic
- ΔH
- -90.0 kJ/mol
Related Reactions
Aluminum Hydroxide Precipitation
Barium Carbonate Precipitation
Barium Sulfate Precipitation
Cadmium Sulfide Precipitation (Yellow)
Calcium Carbonate Precipitation
Calcium Fluoride Precipitation (Fluorite)
Calcium Oxalate Precipitation (Kidney Stones)
Calcium Phosphate Precipitation (Bone Mineral)
Calcium Sulfate Precipitation (Gypsum)
Cobalt(II) Hydroxide Precipitation
Frequently Asked Questions
What is the equation for Chromium(III) Hydroxide Precipitation?
The balanced equation is: CrCl₃ + 3NaOH → Cr(OH)₃↓ + 3NaCl.
What type of reaction is Chromium(III) Hydroxide Precipitation?
Chromium(III) Hydroxide Precipitation is a precipitation reaction.
Is Chromium(III) Hydroxide Precipitation exothermic or endothermic?
Chromium(III) Hydroxide Precipitation is exothermic (releases energy). The enthalpy change (ΔH) is -90.0 kJ/mol.