When ammonia was added to the hydrated nickel chloride

Question

For the equation:

Ni_xCl_z * 6H₂O +yNH₃ →Ni_x (NH₃)_yCl_z +6H₂O

Would the color change from green to purple and the solid formation after being put in ice water be a chemical reaction, when ammonia was added to the hydrated nickel chloride the liquid turned from green to purple and when heated then put in ice water a solid was formed.