Calculate the potential of the following cell `:`
`Pt|underset((2.0M)(1.0M))(Co^(2+),Co^(3+))|underset((1.0M)(4.0M)(1.0M))(Cr^(3+),Cr_(2)O_(7)^(2_-),H^(o+))|Pt`
`E^(c-)._(Co^(2+)|Co^(3+))=-2V,E^(c-)._(Cr_(2)O_(7)^(2-)|Cr^(3+))=+1.0V`

Options

A. `1.024V`
B. `-1.024V`
C. `0.976V`
D. `-0.976V`

Answer

d

Explanation

`Co^(2+) rarr Co^(3+)+e^(-)]xx6`
`14H^(o+)+6e^(-)+Cr_(2)O_(7)^(2-)rarr2Cr^(3+)+7H_(2)O`
`ulbar(6Co^(2+)+14H^(o+)+Cr_(2)O_(7)^(2-)rarr6Co^(3+)+2Cr^(3+)+7H_(2)O)`
`E^(c-)._(cell)=E^(c-)._(c)-E^(c-)._(a)(E^(c-)._(red)Co^(3+)|Co^(2+)=2V)`
`=1-2=-1V`
`E=E^(c-)-(0.059)/(6)log.([Co^(3+)]^(6)[Cr^(3+)]^(2))/([Co^(2+)]^(6)[H^(o+)]^(14)[Cr_(2)O_(7)^(2-)])`
`=-1-0.01log.((1)^(6)xx(1)^(2))/((2)^(6)xx(1)^(14)xx(4))`
`=-1-0.01log(2)^(-8)`
`=-1+0.01xx8xx0.3`
`=-0.976V`