To check if a aqueous solution of Na2S2O3 is supersaturated, what should be added?

To check if a aqueous solution of Na2S2O3 is supersaturated, what should be added?

• A. More water
• B. Heated solution
• C. A crystal of Na2S2O3
• D. Acid to the solution

Answer: (C)

To determine if an aqueous solution of Na2S2O3 is supersaturated, introducing a crystal of Na2S2O3 is the appropriate method. A supersaturated solution contains more solute than it can theoretically hold at a given temperature and pressure, which usually occurs when the solution is prepared at a higher temperature and then cooled down. When a crystal is added to this supersaturated solution, it provides a nucleation site for the excess solute to start crystallizing out. This causes the dissolved Na2S2O3 to precipitate from the solution as it seeks to reach its equilibrium state. If the solution is indeed supersaturated, the addition of the crystal will initiate rapid crystallization, confirming the saturation state of the solution. In contrast, adding more water would dilute the solution but would not establish whether it is supersaturated or not. Heating the solution may increase solubility, potentially leading to the dissolution of additional solute rather than confirming supersaturation. Adding acid could alter the chemical properties and solubility of the compounds in the solution but wouldn't specifically check for supersaturation of Na2S2O3.

To determine if an aqueous solution of Na2S2O3 is supersaturated, introducing a crystal of Na2S2O3 is the appropriate method. A supersaturated solution contains more solute than it can theoretically hold at a given temperature and pressure, which usually occurs when the solution is prepared at a higher temperature and then cooled down.

When a crystal is added to this supersaturated solution, it provides a nucleation site for the excess solute to start crystallizing out. This causes the dissolved Na2S2O3 to precipitate from the solution as it seeks to reach its equilibrium state. If the solution is indeed supersaturated, the addition of the crystal will initiate rapid crystallization, confirming the saturation state of the solution.

In contrast, adding more water would dilute the solution but would not establish whether it is supersaturated or not. Heating the solution may increase solubility, potentially leading to the dissolution of additional solute rather than confirming supersaturation. Adding acid could alter the chemical properties and solubility of the compounds in the solution but wouldn't specifically check for supersaturation of Na2S2O3.