Barium Carbonate (BaCO₃): Properties, Production, Applications, and Safety
1. Introduction
Barium Carbonate (BaCO₃) is an inorganic compound widely used in industries such as ceramics, glass, and chemicals. It is a white, odorless powder with limited solubility in water but soluble in acids. This article explores its properties, synthesis methods, applications, and safety measures in exhaustive detail.
2. Physical and Chemical Properties
2.1 Physical Properties
Molecular Weight: 197.34 g/mol
Appearance: White crystalline solid (rhombic or alpha form at room temperature)
Density: 4.286 g/cm³
Melting Point: 811°C (decomposes to BaO + CO₂)
Solubility:
0.002 g/100 mL (water, 20°C)
Soluble in acids (e.g., HCl, HNO₃)
2.2 Chemical Properties
Thermal Decomposition:
BaCO3→ΔBaO+CO2↑
BaCO3ΔBaO+CO2↑
Reaction with Acids:
BaCO3+2HCl→BaCl2+H2O+CO2↑
BaCO3+2HCl→BaCl2+H2O+CO2↑
Conversion to Barium Sulfate:
BaCO3+H2SO4→BaSO4+H2O+CO2↑
BaCO3+H2SO4→BaSO4+H2O+CO2↑
3. Production Methods
3.1 Carbonation Process
Barium sulfide (BaS) solution is treated with CO₂:
BaS+H2O+CO2→BaCO3+H2S
BaS+H2O+CO2→BaCO3+H2S
3.2 From Barite (Barium Sulfate)
Barite (BaSO₄) is reduced with coke at 1100°C, then carbonated:
BaSO4+4C→BaS+4CO
BaSO4+4C→BaS+4CO
BaS+CO2→BaCO3BaS+CO2 →BaCO3
3.3 Laboratory Synthesis
Precipitation from barium chloride and sodium carbonate:
BaCl2+Na2CO3→BaCO3↓+2NaCl
BaCl2+Na2CO3→BaCO3↓+2NaCl
4. Industrial Applications
4.1 Glass Manufacturing
Acts as a flux to reduce melting temperature.
Improves refractive index and clarity.
4.2 Ceramics and Glazes
Used in tile/porcelain production to stabilize glazes.
Prevents efflorescence in bricks.
4.3 Rat Poison
Toxic to rodents (LD₅₀ ~200 mg/kg for rats).
4.4 Other Uses
Electronics: In thermistors and capacitors.
Chemical Precursor: For other barium compounds (e.g., BaTiO₃).
5. Health and Safety
5.1 Toxicity
Acute Exposure: Causes nausea, vomiting, muscle paralysis.
Chronic Exposure: Linked to kidney damage and hypokalemia.
5.2 Safety Measures
Use PPE (gloves, masks) to avoid inhalation/ingestion.
Store in sealed containers away from acids.
6. Environmental Impact
Barium ions (Ba²⁺) are toxic to aquatic life.
Regulatory limits:
EPA drinking water standard: 2 mg/L.
OSHA PEL: 0.5 mg/m³ (8-hour exposure).
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