<P> An aqueous solution is a solution in which the solvent is water . It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula . For example, a solution of table salt, or sodium chloride (NaCl), in water would be represented as Na (aq) + Cl (aq). The word aqueous means pertaining to, related to, similar to, or dissolved in, water . As water is an excellent solvent and is also naturally abundant, it is a ubiquitous solvent in chemistry . </P> <P> A non-aqueous solution is a solution in which the solvent is a liquid, but is not water . </P> <P> Substances that are hydrophobic (' water - fearing') often do not dissolve well in water, whereas those that are hydrophilic (' water - friendly') do . An example of a hydrophilic substance is sodium chloride . Acids and bases are aqueous solutions, as part of their Arrhenius definitions . </P> <P> The ability of a substance to dissolve in water is determined by whether the substance can match or exceed the strong attractive forces that water molecules generate between themselves . If the substance lacks the ability to dissolve in water the molecules form a precipitate . </P>

A compound dissolves in water to form an aqueous solution