Final answer:
Calcium sulfate dihydrate (CaSO4·2H₂O) is the most soluble form of calcium sulfate in water, both in mol/L and g/L. Its solubility is important in applications such as determining water quality, where a solubility higher than 4.8 × 10⁻³ M may not meet certain standards.
Step-by-step explanation:
It appears that you are referring to calcium sulfate dihydrate, CaSO4·2H₂O, which is indeed a sulfate compound attached to two molecules of water. The presence of water of crystallization, as seen in hydrates, sometimes affects the solubility of the compound in water.
Calcium sulfate dihydrate is known to have a higher solubility compared to its anhydrous counterpart, calcium sulfate (CaSO4). According to your reference, CaSO4·2H₂O is the most soluble Ca salt in both mol/L and g/L, which aligns with the general rule that most sulfates are soluble in water. However, some exceptions to this rule exist, as the sulfates of heavy metals like barium, strontium, lead, and even calcium have relatively low solubility in water.
The solubility you've provided, 4.8 × 10⁻³ M, corresponds to the molar concentration of sulfate and calcium ions in solution, which is higher than a given standard of 2.60 × 10⁻³ M. Although the exact solubility in g/L is not listed here, knowing the molar mass of calcium sulfate dihydrate would allow conversion from molarity to mass per volume.