The dissolution of a metal occurs with the transfer of one or more electrons. The dissolution depends on potential, which may or may not result in passivation. In the case of dissolution of binary alloys, the dissolution may be selective for the less noble metal or simultaneous dissolution may occur. The passivation and depassivation processes on the alloy surface depend on the electrode potential and anions present in the medium. The depassivation may be uniform or with film breakdown at selected sites.