What does saturated mean in relation to a solution at a constant temperature?

• A. No more solute can be dissolved in the solvent at a constant temperature
• B. The solvent can dissolve any amount of solute
• C. The solution is pure
• D. The solvent is saturated with water

Answer: (A)

Saturated means the solution has dissolved as much solute as possible at that temperature. The amount of solute that can stay dissolved in the solvent is fixed for a given temperature, so once this limit is reached, adding more solute won’t dissolve; it remains as a solid or settles out. The system reaches a balance where some molecules dissolve and some come out of solution, keeping the dissolved amount constant.

That’s why the idea that the solvent can dissolve any amount is incorrect. A saturated solution is not pure, because it contains dissolved solute. And saying the solvent is saturated with water isn’t right here, since water is the solvent, not the solute being dissolved.