Final answer:
Cu²⁺ and Zn²⁺ cations are used to construct concentration cells in a galvanic cell experiment, with a salt bridge connecting the two compartments to allow for charge flow without interfering with the reaction.
Step-by-step explanation:
To construct concentration cells using the cations provided in the question (Cu²⁺, Zn²⁺, Mg²⁺, Pb²⁺) we can refer to the example of a galvanic cell where a copper strip is placed in a solution containing Cu²⁺ ions, and a zinc strip is placed in a solution containing Zn²⁺ ions to facilitate a spontaneous electrochemical reaction. Based on the information provided, the example makes use of Cu²⁺ (copper) and Zn²⁺ (zinc) cations, which means these would be used to construct the concentration cells in an experiment.
The galvanic cell described operates by oxidation of zinc metal at the anode where Zn becomes Zn²⁺ and the reduction of Cu²⁺ ions to metallic copper at the cathode. The two compartments are connected by a salt bridge, which contains ions that do not react with the electrolyte or with the electrodes, ensuring the flow of charges without interfering with the redox reaction. Typical ions for a salt bridge could be Na⁺ or K⁺ for the cations and NO3⁻ or SO4²⁻ for the anions.