Silver nitrate at 15°C is unsaturated if the amount of silver nitrate is less than the maximum soluble amount indicated by the solubility curve; it is supersaturated if it contains more than this amount. We utilize solubility curves to identify these states, comparing the amount dissolved to the maximum solubility at a given temperature.
To determine if silver nitrate is unsaturated or supersaturated at 15°C, we need to refer to the solubility curve for silver nitrate.
If a solution contains less silver nitrate than the maximum amount that can dissolve at 15°C according to the solubility curve, it is unsaturated.
If it contains more than the maximum amount that the solubility curve indicates can dissolve at 15°C, it is supersaturated.
For example, using the concept of solubility described above, if 80 g of KNO3 is added to 100 g of water at 30°C and the solubility curve shows that only 48 g can dissolve, the solution is saturated with 32 g of undissolved KNO3.
If the solution is heated to 60°C, where the solubility of KNO3 increases to 107 g, the solution becomes unsaturated as it contains less than the maximum solubility at the higher temperature.
Conversely, if the solution is cooled to 0°C where only 14 g can be dissolved, the excess KNO3 will recrystallize, indicating a supersaturated state when initially encountering the lower temperature.