Question

In gas phase, the H–O–O–H dihedral bond angle in H\(_2\)O\(_2\) is

• A. 145.8°
• B. 111.5°
• C. 90.2°
• D. 147.5°

Hint:

H\(_2\)O\(_2\) is non-planar due to lone pair repulsion, unlike H\(_2\)O.

Answer 1

The Correct Option is B

Step 1: Recall the structure of hydrogen peroxide.
Hydrogen peroxide is a non-planar molecule due to lone pair–lone pair repulsions on oxygen atoms.
Step 2: Consider gas phase geometry.
In gas phase, repulsions are maximum, leading to a skewed (open book) structure.
Step 3: Known experimental value.
The experimentally determined dihedral angle (H–O–O–H) in gas phase is approximately 111.5°.
Step 4: Conclusion.
The correct dihedral angle is 111.5°.