What Does Solubility Mean?
Solubility is defined as the chemical property of a substance that provides the ability for the substance to get dissolved or become soluble in a solvent. This property is also known as “miscibility.” This term also refers to the mixture of fluids (solute and solvent) that mixes easily to form a homogeneous solution. The solute and solvent will become soluble only when they have the same polarity.
Corrosionpedia Explains Solubility
It is often said that the rate of corrosion increases when the corrosion products of the metal are soluble or miscible while the insoluble corrosion products tends to decrease the rate of corrosion. The corrosion rate increases because when corrosion starts, rough surfaces are created on the surface by the removal of large amounts of metal, which most of the time dissolves or becomes miscible in the environment or reacts with the environment to produce a loose adherent porous coating of corrosion. Once this coating is formed, an oxidation reaction speeds up and slowly spreads over a substantial portion of the metal surface until the protective measures are degraded.
In many cases most metals have a natural tendency to become hard when exposed to air, and form a protective layer or covering that makes the corrosion products less soluble and therefore block the metal beneath it from any corrosion. However, metals such as iron form ferrous hydroxide that is somewhat soluble in water (moisture) and thus rust forms.