Question

Consider the following standard reduction potentials in acid solution: The weakest reducing agent listed above is Co Cr Cr3 Mn2 MnO4-

Answer 1

This is an complete question, here is a complete question.

Consider the following standard reduction potentials in acid solution:

`Cr^(3+)+3e^-\rightarrow Cr`
`E^o=-0.74V`

`Co^(2+)+2e^-\rightarrow Co`
`E^o=-0.28V`

`MnO_4^-+8H^++5e^-\rightarrow Mn^(2+)+4H_2O`
`E^o=+1.51V`

The weakest reducing agent listed above is:

(a)
`Cr^(3+)`

(b)
`Cr`

(c)
`Mn^(2+)`

(d)
`MnO_4^-`

Answer : The correct option is, (d)
`MnO_4^-`

Explanation :

As we know that,

The substance having highest positive
`E^o` potential will always get reduced and will undergo reduction reaction and weakest reducing agent or strongest oxidizing agent.

From the standard reduction potentials we conclude that,

`MnO_4^-` having highest positive
`E^o` potential than the other. So, it will always get reduced and will undergo reduction reaction and weakest reducing agent.

Hence, the correct option is, (d)
`MnO_4^-`