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.