The salt BaSO4, formed in the reaction of H2SO4 with Ba(OH)2, is notable for being what?

The salt BaSO4, formed in the reaction of H2SO4 with Ba(OH)2, is notable for being what?

• A. It is highly soluble.
• B. It is insoluble.
• C. It ionizes completely.
• D. It decomposes in water.

Answer: (B)

This question tests understanding of sparingly soluble salts and how the solubility product governs dissolution and precipitation. Barium sulfate has an extremely low solubility in water, described by a very small Ksp (about 1×10^-10). When H2SO4 and Ba(OH)2 react, Ba2+ and SO4^2- ions meet and tend to form BaSO4. Because the product [Ba2+][SO4^2-] quickly exceeds the tiny Ksp, the ions precipitate as solid BaSO4 rather than staying dissolved. That is why this salt is notable: it is insoluble in water, forming a precipitate and remaining largely as solid rather than dissociating into ions. The other statements don’t fit: BaSO4 does not dissolve completely (or ionize completely); it does not decompose in water.

This question tests understanding of sparingly soluble salts and how the solubility product governs dissolution and precipitation. Barium sulfate has an extremely low solubility in water, described by a very small Ksp (about 1×10^-10). When H2SO4 and Ba(OH)2 react, Ba2+ and SO4^2- ions meet and tend to form BaSO4. Because the product [Ba2+][SO4^2-] quickly exceeds the tiny Ksp, the ions precipitate as solid BaSO4 rather than staying dissolved. That is why this salt is notable: it is insoluble in water, forming a precipitate and remaining largely as solid rather than dissociating into ions. The other statements don’t fit: BaSO4 does not dissolve completely (or ionize completely); it does not decompose in water.