Barium Chloride (\(\text{BaCl}_2\)) is a common inorganic compound encountered as a white crystalline solid. This salt is composed of one barium cation and two chloride anions. Barium Chloride is highly soluble in water, dissolving readily and completely to form a clear solution. This characteristic solubility makes it valuable in industrial and laboratory settings, but it also carries significant safety implications.
The Definitive Answer: How Soluble is Barium Chloride?
Barium Chloride is categorized as a highly soluble ionic compound. General solubility rules confirm this, as nearly all chloride salts are soluble in water. The notable exceptions are those formed with silver (\(\text{Ag}^{+}\)), lead (\(\text{Pb}^{2+}\)), and mercury (\(\text{Hg}_2^{2+}\)), none of which apply to Barium Chloride.
The quantitative measure of its solubility shows how readily it dissolves. At \(20^\circ\text{C}\), approximately \(35.8\) grams of anhydrous Barium Chloride can dissolve in 100 milliliters of water. This establishes its classification as very soluble, equating to roughly 358 grams per liter. Its solubility increases with temperature, rising to about \(59.4\) grams per 100 milliliters at \(100^\circ\text{C}\). The resulting transparent solution is an effective conductor of electricity.
The Chemistry of Dissolution
Barium Chloride dissolves due to the nature of its ionic bonds and the properties of water. \(\text{BaCl}_2\) is held together by strong electrostatic forces, known as lattice energy, between the positive Barium ions (\(\text{Ba}^{2+}\)) and negative Chloride ions (\(\text{Cl}^{-}\)). When the solid is introduced to water, the polar nature of water molecules provides the energy needed to overcome this lattice energy. Water molecules have partial negative charges near the oxygen atom and partial positive charges near the hydrogen atoms.
These polar water molecules surround the ions in the crystal lattice, pulling them away from the solid structure. The negative oxygen end of the water molecule is attracted to the \(\text{Ba}^{2+}\) cation, while the positive hydrogen ends are drawn to the \(\text{Cl}^{-}\) anion. This process, called dissociation, results in the ions separating and moving freely. Each ion becomes enveloped by a hydration shell, which stabilizes the ions and prevents them from recombining. The resulting solution contains individual, hydrated \(\text{Ba}^{2+}\) and \(\text{Cl}^{-}\) ions.
Common Applications of Barium Chloride
Barium Chloride is used in several industrial and chemical applications. One frequent use is in chemical analysis as a laboratory reagent for the detection and precipitation of sulfate ions (\(\text{SO}_4^{2-}\)). When a Barium Chloride solution is mixed with sulfate, the highly insoluble white precipitate of Barium Sulfate (\(\text{BaSO}_4\)) immediately forms, confirming the presence of sulfate.
This precipitation reaction is also applied industrially in water treatment processes. It is used particularly for purifying brine solutions in chlor-alkali plants. \(\text{BaCl}_2\) is added to remove sulfate ions from the brine, which otherwise interfere with the electrolysis process used to produce chlorine and sodium hydroxide.
Barium Chloride also serves as a raw material for manufacturing other Barium compounds and has several specialized uses:
- Manufacture of Barium compounds, such as Barium Carbonate and Barium Fluoride.
- Production of pigments.
- Metal heat treatment processes.
- Pyrotechnics, where it imparts a distinct yellow-green color to fireworks.
Safety Considerations
Barium Chloride’s high solubility makes it chemically useful, but it also highlights the compound’s toxicity. Soluble Barium salts, including \(\text{BaCl}_2\), are poisonous if ingested because the Barium ion (\(\text{Ba}^{2+}\)) is readily absorbed into the bloodstream. The toxic effects of the \(\text{Ba}^{2+}\) ion result from its interference with potassium channels in cell membranes. This interference can lead to a decrease in potassium levels in the blood, a condition known as hypokalemia.
Symptoms of Barium poisoning include severe gastrointestinal distress, muscle weakness, and cardiac irregularities. Solutions must be handled with appropriate personal protective equipment and stored securely to prevent accidental ingestion. Disposal involves precipitating the \(\text{Ba}^{2+}\) as the insoluble, non-toxic Barium Sulfate before discarding the waste, neutralizing the hazard.