stable copper hydroxide is prepared by removing ferrous ion from the beginning cupric solution . the ferrous ion is oxidized to ferric ion , and the ferric ion is precipitated by raising the ph of the solution to 3 - 4 . the utilization of phosphate ion both increases the efficiency of oxidation and simultaneously precipitates ferric ion . a second raising the ph of the purified solution precipitates highly pure copper hydroxide that can be harvested .