Is BaSO4 soluble in water?
The correct answer and explanation is:
BaSO4, or barium sulfate, is not soluble in water.
Barium sulfate is a salt composed of barium ions (Ba²⁺) and sulfate ions (SO₄²⁻). When it is added to water, the barium ions and sulfate ions do not separate to form a solution. This is because the ionic bonds between the barium and sulfate ions are very strong, and the energy required to break these bonds exceeds the energy provided by water molecules to solvate (surround and stabilize) the ions. This makes BaSO4 highly insoluble in water.
The solubility of BaSO4 in water is extremely low, measured at approximately 0.000244 grams per 100 milliliters of water at room temperature. This low solubility is due to the low solubility product (Ksp) of BaSO4, which is around 1.1 × 10⁻¹⁰ at 25°C. The Ksp is an equilibrium constant that quantifies the solubility of a compound in water. For BaSO4, the very small Ksp indicates that only a minuscule amount of barium sulfate dissolves in water.
In addition, BaSO4 is often used in industrial applications where its insolubility is an advantage. For example, it is used as a contrast agent in medical imaging (like X-rays and CT scans) because it does not dissolve in the body, allowing it to remain intact for clear imaging of the digestive system.
In conclusion, the low solubility of BaSO4 in water can be attributed to the strength of the ionic bonds between its ions and the limited ability of water molecules to break these bonds. As a result, barium sulfate remains largely undissolved when exposed to water.