Calcium Carbonate Precipitation
CaCl2 + Na2CO3 → CaCO3↓ + 2NaCl
Overview
Calcium chloride reacts with sodium carbonate to precipitate calcium carbonate. CaCO₃ has a Ksp of 3.4 × 10⁻⁹. This is the fundamental reaction behind water softening, where dissolved calcium (hardness) is removed as insoluble carbonate. The precipitate is a white powder.
Participants
| Role | Substance | Coefficient | State |
|---|---|---|---|
| Reactant | Sodium Carbonate Na₂CO₃ | 1 | (aq) |
| Product | Calcium Carbonate CaCO₃ | 1 | (s) |
| Product | Sodium Chloride NaCl | 2 | (aq) |
Everyday Example
Limescale buildup in kettles and pipes is calcium carbonate precipitated from hard water when heated or evaporated.
Industrial Importance
Precipitated calcium carbonate (PCC) is used as a paper filler, in paints, plastics, and pharmaceuticals. Water softening by carbonate precipitation is a major industrial process.
Properties
- Type
- Precipitation
- Reversible
- No
- Energy
- Exothermic
- ΔH
- -13.0 kJ/mol
Related Reactions
Aluminum Hydroxide Precipitation
Barium Carbonate Precipitation
Barium Sulfate Precipitation
Cadmium Sulfide Precipitation (Yellow)
Calcium Fluoride Precipitation (Fluorite)
Calcium Oxalate Precipitation (Kidney Stones)
Calcium Phosphate Precipitation (Bone Mineral)
Calcium Sulfate Precipitation (Gypsum)
Chromium(III) Hydroxide Precipitation
Cobalt(II) Hydroxide Precipitation
Frequently Asked Questions
What is the equation for Calcium Carbonate Precipitation?
The balanced equation is: CaCl₂ + Na₂CO₃ → CaCO₃↓ + 2NaCl.
What type of reaction is Calcium Carbonate Precipitation?
Calcium Carbonate Precipitation is a precipitation reaction.
Is Calcium Carbonate Precipitation exothermic or endothermic?
Calcium Carbonate Precipitation is exothermic (releases energy). The enthalpy change (ΔH) is -13.0 kJ/mol.