Ammonia is added to solutions of cobalt, nickel, and copper 2+ cations. First formation of the hydroxide precipitate is seen, then of the ammonia complex. Pour 0.1M solutions of Cu2+, Co2+, and Ni2+ ...

can react to form ammonium chloride again. This slideshow shows a reversible reaction involving white anhydrous copper(II) sulfate and blue hydrated copper(II) sulfate. The equation for this is ...