A solubility curve is a graphical representation of the solubility of a particular solute in a given solvent with respect to varying temperatures. Generally, temperature is directly proportional to solubility; as temperature increases, solubility also increases. Conversely, as temperature decreases, solubility also decreases.
In an equilibrium state, solubility is the property of matter pertaining to the maximum amount of solute that will dissolve in a given solvent. The term "solute" refers to the chemical substance that is dissolved in a solution, while "solvent" is the component that does the dissolving. The solubility of a solid, liquid or gaseous substance is its concentration in a solution where no additional amount of solute will be dissolved nor deposited. Typically, a substance with a solubility of less than 1 gram per 100 milliliters of solvent is considered insoluble.
Several factors affect solubility, including temperature, pressure, common-ion effect and solute-solvent interactions. The effects of temperature on solubility are well-defined for solid and gaseous materials but not for liquids. In plotting solubility curves for different substances, the standard amount of solvent used is 100 grams or 100 milliliters of water. The curves on the graph illustrate at what specific temperature a particular solute will dissolve in 100 grams or 100 milliliters of water.