electrolysis

The copper anode would be dissolved.
Cu(s) → Cu2+(aq) + 2e-

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In the solution, NaCl is dissociated to give Na+(aq) and Cl-(aq) ions, and water is slightly ionized to give H+(aq) and OH-(aq) ions.

During the electrolysis, Cl- and OH- ions migrate to the copper anode. There are three possible oxidation reactions that may occur at the anode: oxidation of copper, discharge of Cl- ion, and discharge of Na+ ion.
Cu(s) → Cu2+(aq) + 2e- ...... (*)
2Cl-(aq) → 2Cl2(aq) + 2e- ...... (**)
4OH-(aq) → 2H2O(l) + O2(g) + 4e- ...... (***)

Among the above three possible reactions, (***) has the lowest tendency because the concentration of OH- is very low (0.0000001 M at 25oC). In (**), Cl-(aq) ion has a low tendency to be oxidized to Cl­2(g), because Cl­2 is a strong oxidizing agent which can change to Cl- easily. Hence, (*) has the greatest tendency.

(The comparison of the tendencies of the three possible oxidation reactions are included in AL syllabus.)
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