When aqueous solutions of Potassium Carbonate and Copper Nitrate are mixed, the potassium will displace the copper, as it is more reactive, and Potassium Nitrate and Copper Carbonate will be formed.
The equation for this reaction is (ignoring state symbols):
K₂CO₃ + Cu(NO₃)₂ ⇒ 2KNO₃ + CuCO₃
