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Statement I: \([Cr(H_2O)_6]^{3+}\) is more acidic compared to \([Fe(H_2O))6]^{3+}\) Statement II: Both are inner orbital complexes |
If both Statement I and statement II are correct and statement II is the correct explanation of statement I If both Statement I and statement II are true but statement II is not the correct explanation for statement I If Statement I is correct but Statement II is false If Statement I is false but Statement II is correct |
If Statement I is false but Statement II is correct |
The answer is (4) Statement I is false but Statement II is correct. Statement I is false. The acidity of a complex is determined by the stability of the resulting aquated metal ion. The more stable the aquated metal ion, the less acidic the complex. In the case of \([Cr(H_2O)_6]^{3+}\) and \([Fe(H_2O)_6]^{3+}\), the aquated metal ions are \([Cr(H_2O)_6]^{2+}\) and \([Fe(H_2O)_6]^{2+}\). The \([Cr(H_2O)_6]^{2+}\) ion is less stable than the \([Fe(H_2O)_6]^{2+ ion because chromium has a smaller ionic radius than iron. This means that the chromium ion can be less easily hydrated, which makes the aquated ion less stable. Therefore, \([Cr(H_2O)_6]^{3+}\) is less acidic than \([Fe(H_2O)_6]^{3+}\). Statement II is correct. Both complexes are inner orbital complexes, but this is not the reason why \([Cr(H_2O)_6]^{3+}\) is less acidic than \([Fe(H_2O))6]^{3+}\). The reason for the difference in acidity is the stability of the aquated metal ions. |
