If the solvent is a liquid, then almost all gases, liquids, and solids can be dissolved. Here are some examples:
* Gas in liquid:
** Oxygen in water
** Carbon dioxide in water – a less simple example, because the solution is accompanied by a chemical reaction (formation of ions). The visible bubbles in carbonated water are not the dissolved gas, but only an effervescence of carbon dioxide that has come out of solution; the dissolved gas itself is not visible since it is dissolved on a molecular level.
* Liquid in liquid:
** The mixing of two or more substances of the same chemistry but different concentrations to form a constant. (Homogenization of solutions)
** Alcoholic beverages are basically solutions of ethanol in water.
* Solid in liquid:
** Sucrose (table sugar) in water
** Sodium chloride (NaCl) (table salt) or any other salt in water, which forms an electrolyte: When dissolving, salt dissociates into ions.
* Solutions in water are especially common, and are called aqueous solutions.
* Non-aqueous solutions are when the liquid solvent involved is not water.
Counterexamples are provided by liquid mixtures that are not homogeneous: colloids, suspensions, emulsions are not considered solutions.
Body fluids are examples of complex liquid solutions, containing many solutes. Many of these are electrolytes since they contain solute ions, such as potassium. Furthermore, they contain solute molecules like sugar and urea. Oxygen and carbon dioxide are also essential components of blood chemistry, where significant changes in their concentrations may be a sign of severe illness or injury.