Z(aq)0+x+x The amount of solid that dissolves is called the molar solubility, denoted here by x. Since the concentration of the solid is constant and is not included in the Ksp expression, the equilibrium expression for the reaction is Ksp=[Y][Z], or, in terms of molar solubility, Ksp=x2. Part A Enter the the Ksp expression for the solid AB2 in terms of the molar solubility x.