Problem 134 - A Complete Resource Book in Chemistry for JEE Main

Question

Select the correct statement(s): (a) \(\mathrm{BaSO}_{4}\) is soluble in water (b) \(\mathrm{Ba}(\mathrm{OH})_{2}\) is soluble in water (c) \(\mathrm{MgSO}_{4}\) is soluble in water (d) \(\mathrm{CaF}_{2}\) is soluble in water

Step-by-Step Solution

Answer

Statements (b) and (c) are correct: \(\mathrm{Ba}(\mathrm{OH})_{2}\) and \(\mathrm{MgSO}_{4}\) are soluble in water.

Step 1: Analyzing Solubility Rule

According to solubility rules, most sulfate salts are soluble in water. However, there are exceptions, including barium sulfate (\(\mathrm{BaSO}_{4}\)), which is insoluble.

Step 2: Evaluating Ba(OH)_2 Solubility

Barium hydroxide (\(\mathrm{Ba}(OH)_{2}\)) is typically soluble in water. It dissolves, producing barium ions and hydroxide ions in solution.

Step 3: Checking MgSO_4 Solubility

Magnesium sulfate (\(\mathrm{MgSO}_{4}\)) is known to be soluble in water, which is why it is often used in applications such as Epsom salt.

Step 4: Investigating CaF_2 Solubility

Calcium fluoride (\(\mathrm{CaF}_{2}\)) is generally considered insoluble in water as it does not dissolve to a significant extent.

Key Concepts

Sulfate Salts

Sulfate salts are compounds that contain the sulfate ion, \((\text{SO}_4^{2-})\). Generally, most sulfate salts have good solubility in water, meaning they dissolve easily to form a solution. However, this does not hold true for all sulfate salts, as there are exceptions. Certain sulfate salts, like barium sulfate (\(\text{BaSO}_4\)), are insoluble in water. This means that when \(\text{BaSO}_4\) is added to water, it does not dissolve and remains as a solid precipitate.
This property is essential in many practical applications, such as medical imaging, where barium sulfate is used as a contrast agent because it stays undissolved in the digestive system and provides clear X-ray images.

Barium Compounds

Barium compounds are known for their varied solubility properties. While barium sulfate (\(\mathrm{BaSO}_4\)) is considered insoluble in water, other barium compounds such as barium hydroxide (\(\mathrm{Ba(OH)}_2\)) are soluble. When barium hydroxide dissolves in water, it breaks down into barium ions (\(\mathrm{Ba}^{2+}\)) and hydroxide ions (\(\mathrm{OH}^{-}\)), which results in an alkaline solution.

In summary, when learning about barium compounds, remember:

• Barium sulfate is insoluble in water, hence it precipitates.
• Barium hydroxide is soluble, forming an alkaline solution when dissolved.

This distinction in solubility helps in understanding its reactions and uses across different fields like chemistry and industry.

Magnesium Compounds

Magnesium compounds, such as magnesium sulfate (\(\mathrm{MgSO}_4\)), showcase diverse chemical properties. Magnesium sulfate is particularly noted for its excellent solubility in water, making it a useful compound in various applications.

Magnesium sulfate, commonly known as Epsom salt, dissolves readily to provide sulfate and magnesium ions in solution. This soluble nature is why it is often used in bath salts to relieve sore muscles or as a laxative in some healthcare settings. The solubility of magnesium sulfate is a key factor to consider in both household and industrial applications.

Calcium Compounds

Calcium compounds include a range of substances with varying solubility. For instance, calcium fluoride (\(\mathrm{CaF}_2\)) typically exhibits low solubility in water. In practice, this means that it does not dissolve significantly, and most of it will remain as a solid precipitate.

It is important to remember when studying calcium compounds:

• Calcium fluoride is considered insoluble in water.
• Its insolubility is due to the strong ionic bonds in its crystal structure.

Understanding the solubility characteristics of calcium compounds is important for applications in industries such as dentistry and material science, where calcium fluoride's low solubility plays a critical role in product performance.