Solubility Product Constant: The equilibrium constant for the dissolution of a sparingly soluble ionic compound in water. It determines the extent to which the compound dissolves.
Precipitation:The process by which an insoluble solid forms from a solution. In this case, precipitation would occur if iron (III) hydroxide were to come out of solution and form solid particles.
pH:The measure of acidity or alkalinity in a solution. pH can affect the solubility of certain compounds, including iron (III) hydroxide.