Question

The dihedral angles in gaseous and solid phases of H\(_2\)O\(_2\) molecule respectively are

• A. \( 90.2^\circ, 111.5^\circ \)
• B. \( 111.5^\circ, 90.2^\circ \)
• C. \( 101.9^\circ, 94.8^\circ \)
• D. \( 94.8^\circ, 101.9^\circ \)

Hint:

The dihedral angle in H\(_2\)O\(_2\) is affected by intermolecular interactions like hydrogen bonding. - In gas phase, less interaction leads to a larger angle, while in solid phase, hydrogen bonding constrains the structure, reducing the angle.

Answer 1

The Correct Option is B

Step 1: The dihedral angle in a molecule is the angle between two planes containing different atoms of the molecule. Step 2: Hydrogen peroxide (H\(_2\)O\(_2\)) has a non-planar structure due to repulsions between lone pairs of oxygen atoms. - In the gaseous phase, the molecule exists in a skewed conformation with a dihedral angle of 111.5°. - In the solid phase, due to hydrogen bonding, the dihedral angle is reduced to 90.2°. Thus, the correct answer is \( 111.5^\circ, 90.2^\circ \).