Question

What is Eº for the following reaction?

2 Al3+(aq) + 3 Zn(s) -> 2 Al(s) + 3 Zn2+(aq)
Half-Reaction Eº, V
Al3+(aq) + 3 e- -> Al(s) -1.66
Zn2+(aq) + 2 e- -> Zn(s) -0.76

Answer 1

The standard cell potential (E°) for the reaction of 2 Al³+(aq) + 3 Zn(s) -> 2 Al(s) + 3 Zn²+(aq) is -0.90 volts, calculated by adding the reduction potential of aluminum (-1.66 V) to the reversed oxidation potential of zinc (0.76 V).

Step-by-step explanation:

To calculate the standard cell potential (E°) for the given reaction between zinc (Zn) and aluminum ions (Al³+), we need to consider the standard reduction potentials for each half-reaction. For the aluminum half-reaction, Al³+(aq) + 3 e− -> Al(s), the standard reduction potential is -1.66 V. For the zinc half-reaction, Zn(s) -> Zn²+(aq) + 2 e−, the standard reduction potential is given as -0.76 V. However, since zinc is being oxidized, we need to reverse the sign of its standard reduction potential to find its oxidation potential, which becomes 0.76 V.

Now, we add the oxidation potential of zinc to the reduction potential of aluminum to find the overall cell potential:

E°_cell = E°_cathode (Al³+/Al) + E°_anode (Zn/Zn²+) = (-1.66 V) + (0.76 V) = -0.90 V.

Therefore, the standard cell potential for the reaction of 2 Al³+(aq) + 3 Zn(s) -> 2 Al(s) + 3 Zn²+(aq) is -0.90 volts.