Conformers of cis-1,2-dichlorocyclohexane

If the ring atoms of cis-1,2-dichlorocyclohexane were planar the molecule would have a plane of symmetry and be achiral. The chair conformations, however, are chiral. The two chair conformers shown here are the result of chair-interconversions, and are enantiomers. By moving them about, you should be able to see that they are mirror image configurations and are not identical (ie. superimposable). Because of their mirror image relationship, they have identical energy and are present in equal amounts. This is essentially a racemic mixture of enantiomeric conformers, and its optical activity is zero. The spacefilling rendering shows how the axial chlorine (A) is crowded by the two axial hydrogens on the same side of the ring. The equatorial chlorine (E) is much less crowded.
These models can be moved about by clicking on the structure and dragging the mouse. Holding the shift key during this operation allows zooming.

 Show Spacefill Model
 Show Stick Model
 Show Chlorines
 Show Spacefill Model
 Show Stick Model
 Show Chlorines