Question

`Cr_(2)O_(7)^(2-)+I^(-)toI_(2)+Cr^(3+)`
`E_(cell)^(@)=0.79V,E_(Cr_(2)O_(7)^(2-))^(@)=1.33V,E_(I_(2))^(o)` is
A. `-0.10V`
B. `+0.18V`
C. `-0.54V`
D. `0.54V`

Answer 1

Correct Answer - D
`I^(-)` get oxidized to `I_(2)` hence will form anode and `Cr_(2)O_(7)^(2-)` get reduced to `Cr^(3+)` hence will form cathode.
`E_(cell)^(o)=E_("cathode")^(o)-E_("anode")^(o),E_(cell)^(o)=E_(Cr_(2)O_(7)^(-2))-E_(I_(2))^(o)`.
`0.79=1.33-E_(I_(2))^(o),E_(I_(2))^(o)=1.33-0.79,E_(I_(2))^(o)=0.54V`.