Question

Dihedral angle in staggered form of ethane is :

• A. 60$^{\circ}$
• B. 180$^{\circ}$
• C. 0$^{\circ}$
• D. 120$^{\circ}$

Answer 1

The Correct Option is A

The dihedral angle in the staggered conformation of ethane is a fundamental concept in understanding the spatial arrangement of atoms in organic molecules, particularly alkanes. To find the dihedral angle, we must consider the specific arrangement of atoms around the carbon-carbon bond in ethane.

Dihedral Angle: The dihedral angle is the angle between two planes. In ethane, it refers to the angle between the plane containing one C–H bond of one methyl group and the plane containing one C–H bond of the other methyl group.

Staggered Conformation of Ethane: In the staggered conformation of ethane:

• The hydrogens are aligned in a way such that the C-H bonds on the front carbon are equidistant from the C-H bonds on the back carbon.
• This leads to a dihedral angle of 60^{\circ} between the adjacent C-H bonds of the two carbon atoms.

In the staggered conformation, each hydrogen on one carbon atom is perfectly spaced between the hydrogens on the adjacent carbon atom. This minimizes repulsive interactions between electron clouds, consequently stabilizing the molecule.

Let's understand why the other options are incorrect:

• 180^{\circ}: In ethane, a dihedral angle of 180^{\circ} would occur in the anti conformation of larger alkanes, not in the staggered form of ethane.
• 0^{\circ}: This angle represents an eclipsed conformation, where the electron clouds of the C-H bonds directly overlap.
• 120^{\circ}: This angle does not correspond to any typical conformation of ethane or characterize the typical angle in its staggered or eclipsed forms.

Therefore, the correct dihedral angle in the staggered conformation of ethane is 60^{\circ}.