The solubility of iron (ii) hydroxide, fe (oh) 2, is 1.43x10-3 gram per liter at 25oc.

a. write a balanced equation for the solubility equilibrium

Fe (OH) ₂ is solid which partially dissociates into its ions in water. It produces Fe²⁺ and OH⁻ ions by dissociation.

The equation for the reaction is;

Fe (OH) ₂ (s) ⇄ Fe²⁺ (aq) + OH⁻ (aq)

to balance the equation, both side should have same number of atoms in each element.

Left hand side has 1 Fe, 2 O and 2 H atoms while right hand side has 1Fe, 1 O, 1H. hence the equation is unbalanced. to balance that, to the right hand side 2 should be added before the OH⁻ ion. Then the balanced equation is;

Fe (OH) ₂ (s) ⇄ Fe²⁺ (aq) + 2OH⁻ (aq)