Question

What is the voltage of a galvanic cell made with zinc (zn) and aluminum (al)?

Answer 1

Answer : The voltage of galvanic cell made with zinc and aluminum is, 0.90V

Explanation :

We are taking the value of standard reduction potential form the standard table.

`E^0_([Al^(3+)/Al])=-1.66V`

`E^0_([Zn^(2+)/Zn])=-0.76V`

In this cell, the component that has lower standard reduction potential gets oxidized and that is added to the anode compartment. The second forms the cathode compartment.

The half oxidation-reduction reaction will be :

Oxidation :
`Al+3e^-\rightarrow Al^(3+)`
`E^0_([Al/Al^(3+)])=1.66V`

Reduction :
`Zn^(2+)+2e^-\rightarrow Zn`
`E^0_([Zn^(2+)/Zn])=-0.76V`

The expression for standard cell is,

`E^0{cell}=E^0{Anode}+E^0{Cathode}`

`E^0=E^0_([Al/Al^(3+))+E^0_([Zn^(2+)/Zn])`

`E^0=1.66V+(-0.76V)`

`E^0=0.90V`

Therefore, the voltage of galvanic cell made with zinc and aluminum is, 0.90 V

Answer 2

From the reduction standard potentials;
The emf of Zinc = -0.76 V
and the emf of Aluminium = -1.66 V
In a galvanic cell the component with lower standard reduction potential gets oxidized and that it is added to the anode compartment.
Therefore. the voltage of a galvanic cell made with zinc and aluminium will be;
Voltage =Ered- Eoxd
= -0.76 - (-1.66)
= 0.9 V