What is a necessary property of the electrolyte used during the refining of metals by electrolysis?

An electrolyte used during the refining of metals by electrolysis must be an aqueous or molten solution of a suitable metal salt. For electrolysis to occur, the electrolyte must contain free-moving ions. In solid form, ions are held in a fixed lattice; therefore, the salt must be dissolved in water or melted to allow these ions to migrate toward the electrodes. In electrolytic refining, the electrolyte is typically a solution of the same metal being refined. This ensures that metal ions can be consistently transferred from the impure anode to the pure cathode. The Cathode Reaction: During the process, metal ions from the electrolyte are reduced (gain electrons) at the negative cathode, where they deposit as pure metal: Cu2+ + 2e- → Cu (pure metal).