Saturated+Solutions+and+Solubility

Saturated Solutions & Solubility
The opposite of the solution process is known as **crystallization**. This occurs when the concentration of solute particles in solution increases--causing an increase in their chances of colliding with the solid's surface.

A solution in equilibrium with undissolved solvent is said to be **saturated**. This means that no more solute will dissolve if added to the solution. The **solubility** of a solute is the quantity of solute required to make a saturated solution for a given amount of solvent. For instance, the solubility of NaCl in water at 0 degrees Celsius is 35.7g per 100 mL of water (which is the max amount to still maintain a stable equilibrium solution).

A solution is **unsaturated** if less solute is dissolved than needed for a saturated solution. For example, a solution of 25.7g of NaCl per 100 mL of water is unsaturated.

This graph shows how the colder water in the ocean is unsaturated because of the corrosive calcium carbonate which can easily dissolve the minerals. CO2 is the only one in this graph that is not unsaturated.

At times, certain conditions allow for a third type of solution. **Supersaturation** occurs when a solution is formed with more solvent than required for a saturated solution. These solutions are created by heating the solvent to a high temperature, adding the solute, and cooling the solution carefully without disturbance. The addition of a single crystal will cause a supersaturated solution to crystallize due to their extremely instable nature. This a graph that shows supersaturation because the pCO2 (solid line) extends above the saturation point (the dotted line).

Another example:

__**Sources**__ Chemistry: The Chemical Science (9th Edition) http://www.cheresources.com/cryst.shtml http://iodeweb3.vliz.be/oanet/OAimages/Wolf-GladrowGraph.gif//