A galvanic cell is made with aluminum and zinc electrodes. (For Ag^+(aq)+(e^-)--->Ag(s), E=0.80 V and for Cu^2+(aq)+(2e^-)--->Cu(aq), E=0.34 V)
Write the standard cell notation for this cell.
Wouldn't it be silly to use the potentials for copper and silver for an aluminum /zinc cell?
No, it wouldn't be silly to use the potentials for copper and silver to write the standard cell notation for an aluminum/zinc cell. The reason is that the standard cell notation only requires the half-cell reactions and their corresponding standard reduction potentials.
In this case, we have the reduction half-reaction of Ag+ (aq) + e- → Ag (s) with a reduction potential of 0.80 V, and the reduction half-reaction of Cu2+ (aq) + 2e- → Cu (aq) with a reduction potential of 0.34 V. These half-reactions are commonly used references in electrochemistry and can be used to compare the potentials of other half-reactions.
To write the standard cell notation for the aluminum/zinc cell, we need to determine which electrode is the cathode (positive) and which is the anode (negative).
Since the reduction potential of Ag+ (0.80 V) is higher than that of Cu2+ (0.34 V), Ag+ will be reduced at the cathode. Therefore, aluminum will be the anode, and zinc will be the cathode.
The standard cell notation for this cell would then be:
Al (s) | Al3+ (aq) || Zn2+ (aq) | Zn (s)
The single vertical line "|" represents the phase boundary between the solid electrode and the electrolyte solution. The double vertical line "||" represents the salt bridge or porous barrier that allows ion flow while maintaining electrical neutrality.
Yes, you are correct. It would not be appropriate to use the potentials for copper and silver in this case, as the cell is made with aluminum and zinc electrodes. Instead, we need to use the potentials for the reactions involving aluminum and zinc.
The reaction for the oxidation half-reaction at the anode is:
Aluminum (Al) --> Aluminum ion (Al^3+) + 3 electrons
The reduction half-reaction at the cathode is:
Zinc ion (Zn^2+) + 2 electrons --> Zinc (Zn)
Therefore, the standard cell notation for this galvanic cell would be:
Al(s) | Al^3+(aq) || Zn^2+(aq) | Zn(s)
Note that the double vertical lines represent the salt bridge or porous barrier separating the two half-cells. The anode is on the left and the cathode is on the right.