# Solution Formation

## Key Questions

Clearly the identity of both the solute and the solvent affect solution formation.

#### Explanation:

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?

• A solution is a homogeneous mixture of two or more substances.

There are many types of solutions.

Gas in Gas

• Air — oxygen and other gases dissolved in nitrogen.

Gas in Liquid

• Fish tank — oxygen in water.
• Carbonated beverages — carbon dioxide in water.
• Blood — oxygen and carbon dioxide are essential components of blood chemistry.

Liquid in Liquid

• Windshield washer fluid — methanol in water.
• Alcoholic beverages — ethanol and other solutes in water.
• Vinegar — acetic acid in water.

Solid in Liquid

• Maple syrup — sugar in water
• Brine — salt in water.
• Body fluids — complex aqueous solutions of sugar, urea, electrolytes, and many other solutes.

Gas in Solid

• Hydrogen dissolves rather well in palladium and tin.

Liquid in Solid

• Dental amalgam — mercury in silver, tin, and copper.
• Hexane in paraffin wax

Solid in Solid

• Steel — carbon atoms in a crystalline matrix of iron atoms.
• Bronze — copper and tin.
• Brass — copper and zinc.