Write the possible conformations of ethane and explain which is more stable.

Explanation

Conformation of ethane : The conformational isomers of a given alkane are obtained by rotation about C-Cbond and they are represented by Newman projections or Line - Wedge or Sawhorse projections. Newman projections and energy diagrams for the various conformations of ethane are given below.

Staggered (S) occurs at Dihedral angle `60^(@), 180^(@), 300^@)`
Rotation about the carbon - carbon bond in ethane is though very rapid, not completely free. Two conformations of ethane known as staggered conformation (5) and the eclipsed conformation (E), are very important though infinite number of confomation are possible.
The C-H bonds in the staggered conformation are arranged so that each one bisects the angledefined by two C-H bonds on adjacent carbon. In the eclipsed conformation each C-H bond is aligned with a C-H bond on .adjacent carbon.
In the staggered one the distance between the hydrogen nuclei is `2.55 A^(@)` but in eclipsed 2.29 Ao. The staggered and elipsed conformations are interconvertible by rotation of one carbon with respect to the other around the o bond that connects them. Different conformations of the same molecule are also called confórmers or rotamers. Stability":
`to` Staggered (S) form is more stable than eclipsed. Because in case of eclipsęd form electronic repulsions are high and in case of staggered form electronic repulsions are minimum.