Question

Given: \[\ce{E^{\circ}_{Cl_2/Cl^-}}\] = 1.36 V, \[\ce{E^{\circ}_{Cr^{3+}/Cr}}\] = −0.74 V

\[\ce{E^{\circ}_{Cr_2O^{2-}_7/Cr^{3+}}}\] = 1.33 V, \[\ce{E^{\circ}_{MnO^-_4/Mn^{2+}}}\] = 1.51 V

Among the following, the strongest reducing agent is:

Options

• Cr³⁺

• Cl⁻

• Cr

• Mn²⁺

Answer 1

Cr

Explanation:

A strong reducing agent has a low (more negative) standard reduction potential, meaning it readily loses electrons (gets oxidised).

From the data:

\[\ce{E^{\circ}_{Cr^{2+}/Cr}}\] = −0.74 V

Cr is oxidised to Cr³⁺.

All other values are more positive.

Thus, Cr has the most negative E° value, making it the strongest reducing agent among the options.