Final answer:
In an electrolytic cell, magnesium (Mg) undergoes oxidation at the anode, whereas copper (Cu) undergoes reduction at the cathode. The anode is where oxidation, or the loss of electrons, takes place, and the cathode is where reduction, or the gain of electrons, occurs.
Step-by-step explanation:
In an electrolytic cell, the reaction involves applying an external voltage to drive a nonspontaneous reaction. When considering Mg (magnesium) and Cu (copper) within such a cell, the process that each undergoes depends on their role as anode or cathode. For example, in a Copper-Zinc electrolytic cell, where the reactions are Mg (s) → Mg2+ (aq) + 2e- (oxidation) and Cu2+ (aq) + 2e- → Cu (s) (reduction), magnesium (Mg) is oxidized at the anode and copper (Cu) is reduced at the cathode. Oxidation always occurs at the anode and represents the loss of electrons. Reduction occurs at the cathode and involves the gain of electrons.