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What is Solubility?
Solubility describes a solute's ability to dissolve in a particular solvent. Solubility is measured in the mass of solute per volume of solvent needed to create a saturated solution. A substance's solubility, particularly in water, is given alongside other physical properties of the substances such as boiling point.
Soluble and Insoluble
Some solute and solvent combinations are not favorable for dissolution. If the properties of the substances do not form an interaction, dissolution will not occur. The solute is called insoluble in that solvent. Insoluble solute can have a minimal solvation in the solvent, but the majority is undissolved. Liquids that mix to form solutions are called miscible. When two liquids do not mix to form a solution they are called immiscible.
The phrase "like dissolves like" is statement used meaning that solutes will solvate in solvents with similar properties. Polar solutes will dissolve in polar solvents. Non-polar solutes will dissolve in non-polar solvents. For example, polar salts will solvate in water. Non-polar organic molecules will solvate and interact with non-polar solvents. One example is grease, a non-polar hydrocarbon will solvate in hexanes, a non-polar hydrocarbon solvent.
Unknown Compound or Solubility
Solubility tests can be carried out to determine the identity of an unknown substance or to determine a known substances solubility. The tests are performed by taking a small amount of the material and testing the solubility with known solvents such as water, alcohols, acetonitrile, ether, and more. Qualitative results are recorded by visually assessing the solubility. The solubility of an unknown compound can indicate features of compound such as polar or non-polar.
