Question

The \[\ce{E^{\circ}_{M^{3+}/M^{2+}}}\] values for Cr, Mn, Fe and Co are −0.41, +1.57, +0.77 and +1.97 V respectively. For which one of these metals the change in oxidation state from +2 to +3 is easiest?

Options

• Cr

• Mn

• Fe

• Co

Answer 1

Cr

Explanation:

The \[\ce{E^{\circ}_{M^{3+}/M^{2+}}}\] ratio is the most negative for Cr. This suggests that Cr³⁺ has the least probability to transition to Cr²⁺. In contrast, Cr²⁺ is more likely to convert to Cr³⁺, making the transition from +2 to +3 easier.