I₂ is violet in the solid as well as in gas phase. However in acetone or ethanol, it turns brown. Choose the… · ABC26IN1137
Subject: Inorganic Chemistry · Chapter: Coordination Chemistry · Topic: Charge Transfer Spectra · Exam: CSIR NET JUNE 2019 · Marks: 2 · Difficulty: Medium
$\mathrm{I}_{2}$ is violet in the solid as well as in gas phase. However in acetone or ethanol, it turns brown. Choose the correct statement(s) for this colour change:
\[ \begin{array}{l} \text{(a) Dissociation of } \mathrm{I}_2 \text{ in atomic state} \\ \text{(b) Interaction of low-lying } \sigma^{*}\text{-orbital of iodine with lone pair of O (solvent)} \\ \text{(c) Formation of a charge-transfer complex} \end{array} \]
(a)(a) only
(b)(b) only
(c)(a) and (b) only
(d)(b) and (c) only
Answer
Answer: D ✓ checked by 4AB · confidence high
Explanation
In donor solvents the oxygen lone pair donates into the low-lying σ* of I₂ (a charge-transfer complex), blue-shifting the π*→σ* band from violet to brown; I₂ does not dissociate. (b) and (c).