Question

Depict the electrochemical cell in which the cell reaction is

\[\ce{2Cr_{(s)} + 3Cu{^{2+}_{(aq)}} -> 2Cr{^{3+}_{(aq)}} + 3Cu_{(s)}}\]

1. mark the anode and the cathode;
2. show movement of electrons and flow of current;
3. write the half cell reactions.

Answer 1

Given: \[\ce{2Cr_{(s)} + 3Cu{^{2+}_{(aq)}} -> 2Cr{^{3+}_{(aq)}} + 3Cu_{(s)}}\]

i. In the given reaction, chromium (Cr) is the anode and copper (Cu) is the cathode.

ii. Electrons flow from anode (Cr) to cathode (Cu) through the external wire. Conventional current flows from cathode to anode (opposite to electron flow). A salt bridge is used to maintain electrical neutrality by allowing the movement of ions between the half-cells.

iii. At anode (oxidation): \[\ce{Cr_{(s)} -> Cr{^{3+}_{(aq)}} + 3e-}\]

At cathode (reduction): \[\ce{Cu{^{2+}_{(aq)}} + 2e- -> Cu_{(s)}}\]

Overall cell reaction: \[\ce{2Cr_{(s)} + 3Cu{^{2+}_{(aq)}} -> 2Cr{^{3+}_{(aq)}} + 3Cu_{(s)}}\]