Lead crystals forming. Time-lapse microscopy footage of crystals of lead forming on zinc during a metal displacement reaction. Zinc is a more reactive metal than lead. Over time, zinc displaces (replaces) the lead in the lead nitrate solution to form a solution of zinc nitrate. The lead that is displaced out of solution crystallizes on the zinc. The chemical reaction is: Zn + Pb(NO3)2 -> Zn(NO3)2 +Pb.