QJEEM10Ch4151: JEE Main 2010 Chemistry - Class 12 JEEM10Ch4151 Solution: The correct order of E M 2 + / M o values with negative sign…

Question

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The correct order of

E_{M^{2 +} / M}^{o}

values with negative sign for the four successive elements Cr, Mn, Fe and Co is :

Accepted Answer

The value of

E_{M^{2 +} / M}^{\circ}

for given metal ions are

E_{M n^{2 +} / M n}^{\circ} = - 1.18 V,

E_{C r^{2 +} / C r}^{\circ} = - 0.9 V,

E_{F e^{2 +} / F e}^{\circ} = - 0.44 V

and

E_{C o^{2 +} / C o}^{\circ} = - 0.28 V .

So when we consider these values with a negative sign (i.e., taking the magnitude of the negative potentials), we get the values as :

Therefore, the correct order of $E_{M^{2+}/M}^\circ$ values with the negative sign will be :

Mn > Cr > Fe > Co

This matches with option A.

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