# What affects solution formation?

Jan 2, 2016

The most common solvent is water. Why? For a start it covers 2/3 of the planet. Water is an exceptionally good solvent for ionic species, because it can solvate ions to form $N {a}^{+} \left(a q\right)$ and $C {l}^{-} \left(a q\right)$.
The $\left(a q\right)$ designation refers to the aquated ion; in solution this means the ion is surrounded by, or aquated by approx. 6 water molecules, i.e. ${\left[N a {\left(O {H}_{2}\right)}_{6}\right]}^{+}$. Water is exceptionally good at dissolving SOME ionic species because it can solvate ions; but some ion pairs i.e $A g C l$ have little solubility in water. Water is conceived to have a partially negative central oxygen atom, bound to partially positive hydrogen atoms. This charge separation is referred to as polarity and allows ion solvation, and water is the best example of a polar solvent.
Hexanes is a non-polar solvent. Hexanes will dissolve ethanol (${C}_{2} {H}_{5} O H$), but not methanol (${H}_{3} C O H$). Why not?