Aluminium displaces hydrogen from acids, but copper does not. A galvanic cell prepared by combining `Cu//Cu^(2+)` and `Al//Al^(3+)` has an emf of 2.0V at 298K. If the potential of copper electrode is +0.34V and that of Aluminium electrode is

Options

A. `-2.3V`
B. `+2.34V`
C. `-1.66V`
D. `1.66V`.

Answer

C

Explanation

Cell representation is
`Al|Al^(2+)||C u^(2+)|Cu`
`E_("cell")=E_(Cu^(2+))+_(//Cu)-E_(Al^(3))+_(//Al)`
`2.0V== 0.34V-E_(Al^(3+)//Al)`
`E_(Al^(3+)//Al)=0.34V-2.0V=-1.66V`