the Zn(OH)2 precipitation reaction equation: Zn2+ + 2OH- = Zn(OH)2 the Zn(OH)42- complex formation equation: Zn2+ + 4OH- = Zn(OH)4^2- Precipitate will not form. Solution the Zn(OH)2 precipitation reaction equation: Zn2+ + 2OH- = Zn(OH)2 the Zn(OH)42- complex formation equation: Zn2+ + 4OH- = Zn(OH)4^2- Precipitate will not form..