There are some fundamental ideas of any subject, which you must grasp to be able to understand the more complex issues. One such concept is that of an unsaturated solution. When you work in chemistry labs, you essentially deal with solutions of all kinds. Most chemicals are used in the form of a solution and hence it's important that their properties be studied in detail.
What is a Solution?
A homogeneous mixture which is made up of two or more compounds, is called a solution. The word 'homogeneous' signifies a uniform physical state or composition. There are two prime type of components of a solution. The largest of the components is known as the 'solvent', while rest of the components are known as 'solutes'. The reason for the whole solution having uniform composition is the fact that solutes 'dissolve' into the solvent.
The solution may be that of solids dissolved in a liquid, gases dissolved in gases, liquids dissolved in liquids, and even solids dissolved in solids. In chemistry, we mostly deal with solutions which have solids dissolved in liquids.
The solubility of a solute is its ability to dissolve readily in a solution. This solubility may change according to the nature of the solvent and its temperature. Temperature affects the molecular vibrations of a solvent and the intermolecular attractive forces, which are responsible for causing dissolution of solutes in a solvent. Pressure and the polarization among solute and solvent molecules have an impact on the solubility of any solution.
It is a fact of observation that polar solvents dissolve ionic compounds better, while organic solvents dissolve other organic compounds more readily. Water is known as a universal solvent due to its unique ability of dissolving various types of compounds.
What is Saturation Level of a Solution?
It is the maximum amount of solute that can be dissolved in a solution. It is found to be a function of temperature. As the temperature of a solution varies, its capacity to dissolve solutes changes. If you draw a graph of temperature against solubility, for most solutions, it's an inverted 'U' type of a graph. The solubility increases with increasing temperature, reaches a maximum, and then drops down as the temperature increases further.
An unsaturated solution is one that still has a capacity to dissolve more solute. Any such solution, is in a condition where it still hasn't reached the saturation limit. An example is NaCl in water. When you add a teaspoonful of salt to a glass of water, it easily dissolves in it. That's because, it is unsaturated. You will find many such examples in chemistry lab experiments. As against this, a saturated solution is one which can no longer dissolve any more solute.
In the simplest of words, it is a solution, with a solvent which has 'room' for dissolving more solute in it. On the other hand, a saturated solution is one in which the solvent has no more 'vacancy' to accommodate any more solute, through dissolution.