A solubility curve is a graph showing the relationship between temperature and the amount of a substance (solute) that can dissolve in a specific amount of solvent (usually expressed in grams per 100 grams) at that temperature. It tells you how much solute you can dissolve in a solvent at different temperatures.
The axes: The x-axis typically represents temperature, while the y-axis represents the solubility of the solute.
The curve: The line itself shows the trend of how solubility changes with temperature. For many solid solutes in water, the solubility increases as the temperature increases. However, for gases, the solubility generally decreases with increasing temperature.
Regions of the curve: The curve can be used to identify different types of solutions:
Unsaturated solution: A solution with less solute than the maximum amount possible at that temperature is unsaturated. This region falls below the curve.
Saturated solution: A solution containing the maximum amount of solute that can dissolve at a particular temperature is saturated. This point lies on the curve itself.
Supersaturated solution: A solution with more solute than is typically stable at that temperature is supersaturated. This region is above the curve. Supersaturated solutions are unstable and can eventually precipitate excess solute out of the solution.
Solubility curves are useful tools in chemistry for various purposes, including:
Predicting solubility: You can use the curve to estimate how much of a substance will dissolve in a solvent at a specific temperature.
Comparing solubility: By comparing solubility curves of different substances, you can see which one is more soluble at a given temperature.
Crystallization: Solubility curves help predict which solute will crystallize first when a solution containing multiple solutes is cooled down.