Barium Chloride
Properties
| State | Solid at room temperature |
| Color | White crystalline solid |
| Solubility | Soluble in water (37.5 g/100 mL at 25 °C) |
| Melting Point | 961 °C |
| Boiling Point | 1560 °C |
About Barium Chloride
Barium chloride is the soluble barium salt that gets used as the analytical reagent for sulfate detection, and the chemistry is satisfyingly clean: drop a few drops of BaCl2 solution into any aqueous sample containing sulfate, and the dense white precipitate of BaSO4 falls out with a Ksp of 1.1 × 10⁻¹⁰ — about four orders of magnitude less soluble than the next-most-insoluble alkaline-earth sulfate. The precipitate is also acid-resistant, which separates sulfate from carbonate (which dissolves in HCl) in the classical Group 5 anion test scheme. This same precipitation chemistry, run on a quantitative basis with weighed precipitates, was the standard gravimetric sulfate determination for the entire 19th and 20th centuries before instrumental ion chromatography displaced it. The handling reality of BaCl2 is sharply different from BaSO4: while BaSO4's extreme insolubility makes it the safe contrast agent for medical imaging, BaCl2's moderate solubility releases free Ba²⁺ ions that block potassium channels in muscle cells, producing severe hypokalemia, cardiac arrhythmias, and skeletal-muscle paralysis at sub-gram doses. The lethal oral dose is around 1–2 grams in adults. Industrially, BaCl2 is used as a flux in magnesium alloy refining, in water treatment to precipitate sulfate impurities, and in the manufacture of barium pigments and barium-doped glass for radiation shielding.
Where you'll encounter it
If you've taken general or analytical chemistry, the first time you saw a precipitation reaction in a test tube, the partners were probably barium chloride and sodium sulfate — the dense white BaSO4 precipitate falls out almost instantly, which makes it the canonical demonstration of an insoluble-product reaction. In a teaching lab, BaCl2 also appears in the unknown anion-identification scheme, where it's used together with AgNO3 to discriminate sulfate, chloride, carbonate, and phosphate from each other based on different solubility products. Outside teaching, the reagent shows up in industrial water-treatment applications where dissolved sulfate must be removed (typical in oilfield produced-water handling and certain electroplating processes), and as a starting material for other barium chemistry — the BaSO4 contrast agent itself often starts life as BaCl2 reacted with Na2SO4 under controlled conditions to give a fine, well-characterized precipitate.
Common Uses
- Analytical reagent for sulfate-anion qualitative testing
- Gravimetric sulfate determination via BaSO4 precipitation
- Sulfate-removal agent in industrial water treatment
- Magnesium-alloy fluxing agent in metal refining
- Precursor for other barium compounds and barium-doped pigments
Safety Information
Highly toxic — soluble Ba²⁺ ions block potassium channels in muscle cells, causing hypokalemia, cardiac arrhythmias, and potentially fatal paralysis at oral doses of 1–2 g in adults. Distinctly more hazardous than insoluble BaSO4, which passes through the GI tract harmlessly. Use lab-grade gloves and avoid any food-area handling. The clinical antidote for barium poisoning is intravenous potassium chloride and oral magnesium sulfate (which precipitates the unabsorbed barium as BaSO4 in the gut). GHS H301, H332.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.