Displacement reaction. Image 2 of 2. Zinc (Zn) metal after reacting with copper (II) sulphate (CuSO4) solution (pale blue). Solid copper (Cu, black) plates the zinc because the copper was replaced in solution by the more reactive zinc. The original blue colour is diluted as colourless zinc sulphate forms in a displacement or substitution reaction. For an image of the zinc being added, see image A500/362.