The metal ion is Pb2+. The white precipitate PbCl2 is insoluble in cold water but soluble in hot water. The precipitation reaction is: Pb2+(aq) + 2 HCl(aq) => PbCl2(s) + 2 H+(aq) Solution The metal ion is Pb2+. The white precipitate PbCl2 is insoluble in cold water but soluble in hot water. The precipitation reaction is: Pb2+(aq) + 2 HCl(aq) => PbCl2(s) + 2 H+(aq).