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Given that, Co^(3+) +e^(-)rarr Co^(2+) E...

Given that, `Co^(3+) +e^(-)rarr Co^(2+) E^(@) = +1.82 V`
`2H_(2)O rarr O_(2) +4H^(+) +4e^(-), E^(@) =- 1.23 V`.
Explain why `Co^(3+)` is not stable in aqueous solutions.

Text Solution

Verified by Experts

The `E_("cell")` can be calculated as follows:
`4 xx [ Co^(3+) +e^(-) rarr Co^(2+)], E^(@) = +1.82 V`
`1 xx [2H_(2)O rarr O_(2) +4H^(+) +4e^(-)] , E^(@) =- 1.23 V`.
Add: `4Co^(3+) +2H_(2)O rarr 4Co^(2+) +4H^(+) +O_(2), E^(@) = 1.82 - 1.23 = +0.59 V`.
Since, `E_("cell")` is positive the cell reaction is spontaneous. This means that `Co^(3+)` ions will take part in the reaction. Therefore, `Co^(3+)` is not stable.
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