JEE MAIN - Chemistry (2019 - 9th January Morning Slot - No. 14)
Two complexes [Cr(H2O)6]Cl3 (A) and [Cr(NH3)6]Cl3 (B) are violet and yellow coloured, respectively. The incorrect statement regarding them is :
$$\Delta $$0 values of (A) and (B) are calculated from the energies of violet and yellow light, respectively
both are paramagnetic with three unpaired electrons
both absorb energies corresponding to their complementry colors.
$$\Delta $$0 value for (A) is less than that of (B).
Explanation
NH3 is a strong field ligand.
H2O is weak field ligand.
Let $$\Delta $$violet is the crystal field splitting energy of complex A and $$\Delta $$yellow is for complex B.
$$ \therefore $$ $$\Delta $$yellow > $$\Delta $$violet.
We know, $$\Delta $$ = $${{hc} \over {{\lambda _{absorb}}}}$$
Violet color will absorb yellow color and yellow color will absorb violet color.
$$ \therefore $$ $$\Delta $$yellow = $${{hc} \over {{\lambda _{violet}}}}$$
and $$\Delta $$violet = $${{hc} \over {{\lambda _{yellow}}}}$$
So, $$\Delta $$o of A is calculated from energy of yellow light and $$\Delta $$o of B is calculated from energy of violet light.
H2O is weak field ligand.
Let $$\Delta $$violet is the crystal field splitting energy of complex A and $$\Delta $$yellow is for complex B.
$$ \therefore $$ $$\Delta $$yellow > $$\Delta $$violet.
We know, $$\Delta $$ = $${{hc} \over {{\lambda _{absorb}}}}$$
Violet color will absorb yellow color and yellow color will absorb violet color.
$$ \therefore $$ $$\Delta $$yellow = $${{hc} \over {{\lambda _{violet}}}}$$
and $$\Delta $$violet = $${{hc} \over {{\lambda _{yellow}}}}$$
So, $$\Delta $$o of A is calculated from energy of yellow light and $$\Delta $$o of B is calculated from energy of violet light.
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